• • • ' K* -J.VL Atf .W-' oi "1^ I v^ T$ 3Noia3w do Aavaan ivnoiivn snidiqsw do Aavaan ivnoiivn 3NIDIQ3W do Aavaan AHvaan ivnoiivn snidiosw do Aavaan ivnoiivn 3nidiq3w do Aavaan ivnoiivn iVRY OF MEDICINE NATIONAL LIBRARY OF MEDICINE NATIONAL LIBRARY OF MEDICINE 1^ PRINCIPLES AND PRACTICE OF DENTISTRY. Valuable Works Connected with Dentistry PUBLISHED BY LINDSAY & BLAKISTON, PHILADELPHIA. HARRIS (CHAPIN A.), M.D., D.D.S. The Principles and Practice of Dentistry. Tenth Revised Edition. . In great part Rewritten, Rearranged, and with many new and important Illustrations. Edited by P. H. Austen, M.D., Professor of Dental Science and Mechanism in the Baltimore College of Dental Surgery. With nearly 400 Illustrations. Royal octavo. Price, in cloth, 6.50; in leather, 7.50 HARRIS (CHAPIN A.), M.D., D.D.S. A Dictionary of Medical Terminology, Dental Sur- gery, and the Collateral Sciences. Fourth Edition, Carefully Revised and Enlarged. By Ferdinand J. S. Gorgas, M.D., D.D.S., Professor of Dental Surgery in the Baltimore College, etc. Royal octavo. Price, in cloth, 6.50; in leather, 7.50 RICHARDSON (JOSEPH), tf.D.S. A Practical Treatise on Mechanical Dentistry. Third Edition, much Enlarged. With over 150 Illustrations. Octavo. Price, in cloth, ; in leather, TAPT (JONATHAN), D.D.S. A Practical Treatise on Operative Dentistry. Third Edition, thoroughly Revised, with Additions. Over 100 Illustrations. Octavo. Price, in cloth, 4.25; in leather, 5.00 WEDL (CARL), M.D. Dental Pathology. With Special Reference to the Anatomy and Physiology oi the teeth, and notes by Thos. B. Hitchcock M D Prof, of Dental Pathology, Harvard University. 105 Illustrations! Price, in cloth, 3.50 ; in leather, 4.50 HANDY (WASHINGTON R.), M.D. Handy's Text-Book of Anatomy and Guide to Dis- sections. For the use of Students. 312 Illustrations. Octavo. T ,-,^„_ * Price, cloth, 3.00 LEBER AND ROTTENSTEIN (Drs.) Dental Caries and Its Causes. An Investigation into the Influence of luingi in the destruction of the Teeth. With Illustra tl0nS- Price, cloth, 1.25 SEWILL (H. E.), M.R.C.S., Eng., L.D.S. The Student's Guide to Dental Anatomy and ^nr> gery. With 77 Illustrations. Price cloth 1 50 SANSOM (ARTHUR ERNEST), M.B Chloroform. Its Action and Administration. price doth 1 50 TURNBULL (LAURENCE), M.D. The Advantages and Accidents of Artificial An^c thesia. A Manual of Anaesthetic Agents, Modes of AdmintSot etc. Second Edition, Enlarged. 25 Illustrations. Price, cloth, 1.50 THE PRINCIPLES AND PRACTICE OF DENTISTRY", INCLUDING ANATOMY, PHYSIOLOGY, PATHOLOGY, THERAPEUTICS, DENTAL SURGERY AND MECHANISM. BY CHAPIN A. HARRIS, M.D., D.D.S., LATE PRESIDENT OP THE BALTIMORE DENTAL COLLEGE, AUTHOR OF " DICTIONARY OF MEDICAL TERMINOLOGY AND DENTAL SURGERY." Heath (Edition. REVISED AND EDITED BY PHILIP H. AUSTEN, M.D., ^ WITH FOUR HUNDRED AND NINE ILLUSTRATIONS. PHILADELPHIA: LINDSAY AND BLAKISTON. 187 9. wu It'll NATIONAL LIBRARY OF MEDICINE - BETHESDA 14, MD. Entered according to Act of Congress, in the year 1871, by LINDSAY AND BLAKISTON, the Office of the Librarian of Congress, at Washingtc PRINTED BY SHERMAN ft CO. DEDICATION TO THE SEVENTH EDITION. TO THOMAS E. BOND, M.D., PROFESSOR OF SPECIAL PATHOLOGY AND THERAPEUTICS IN THE BALTIMORE COLLEGE OF DENTAL SURGERY, AS A TOKEN OF GRATITUDE FOR MUCH KINDNESS, AND AS A TESTIMONY OF RESPECT AND ESTEEM FOR GREAT PROFESSIONAL AND PRIVATE WORTH, IS RESPECTFULLY DEDICATED, BY HIS FRIEND, 4KB OBEDIENT SEAVANT, THE AUTHOR. EDITOR'S PREFACE. T71ROM the date of its publication, in 1841, Harris's " Principles -*- and Practice " has taken the first place among Dental Text- Books—a precedence which the author, by careful revision of suc- ceeding editions, maintained for twenty years. In pursuance of the author's plan, the present editor made many additions, chiefly in the specialty of Mechanism, to the first posthumous edition, issued in 1863 and republished in 1866. The great advances made, since the death of the author, in Dental Physiology, Pathology, Surgery, and Mechanism, demand now, for the maintenance of the deservedly high reputation of the work, a revision in all its parts more complete than any preceding one. At the earnest solicitation of the author's family and of the publishers, the editor has, with much diffidence, undertaken this task. He has carefully revised that part which an experience of twenty years, as a teacher, has made him competent to investigate. The other parts he assigned to gentlemen of acknowledged profi- ciency in their respective departments. To Thomas S. Latimer, M. D., Prosector in the Baltimore Dental College, was assigned Part I., Anatomy and Physiology, and a portion of Part II. Minute details of microscopical and physiological research, and the full discussion of speculative the- ories, are out of place in a text-book. Avoiding such minuteness, Dr. Latimer has given the present state of Dental anatomy, physi- ology, and pathology in a manner worthy of his well-known fine scholarship and extensive professional knowledge. To Ferdinand J. S. Gorgas, M.D., D.D.S., Professor of vii viii editor's preface. Dental Surgery in the Baltimore College, was assigned the re- mainder of Part II. and the entire Part III., Surgery. His long experience in surgical practice, and as a teacher, eminently qualify him for a revision, the excellence of which will be acknowledged, whatever the differences of opinion and practice in this department of Dentistry. Norman W. Kingsley, D.D.S., late Professor in the New York Dental College, has prepared, expressly for this edition, the entire Chapter on Palatine Defects. His world-wide reputa- tion, in this Dental Specialty, is ample guarantee for his faithful rendering of this important subject. To each of these gentlemen was given entire control of the extent and manner of revising the parts severally entrusted to them; the editor having simplified the author's original arrange- ment of parts, and suggested throwing together certain chapters and sections, the separation of which, in previous editions, was a source of some confusion. The Editor, in his revision of Part IV., Mechanism, has found it necessary entirely to re-arrange his revision of 1863, and greatly to enlarge it. By the omission of some obsolete processes and unimportant details, by shortening certain descriptions, and by the utmost conciseness consistent with clearness of explanation, he has, within the same number of pages, given nearly twice the amount of information. He has aimed to omit no subject of pres- ent or prospective importance. As a teacher, it has been his duty to examine all subjects impartially, yet to express very decidedly his own views. As editor, he has aimed at equal impartiality, tempering his dissent with courtesy, when its expression is neces- sary. The last ten years have nearly revolutionized Dental Mechanism, by the unprecedented rapidity with which hard rubber has taken the place of gold and other materials. Unfortunately, this change has been accompanied by certain principles and methods of prac- tice which have greatly injured Dentistry as an Art. Reference is made to this evil and its danger, in the Introduction: the earnest # editor's preface. ix desire to aid in arresting it, is the editor's only apology for an oc- casional severity of comment found in this Fourth Part. The editor's name is sometimes introduced for various reasons, unnecessary to state; but at no time with the intention of arrogat- ing to himself the exclusive right to ideas which, very probably, have also occurred to others, and been acted upon within the limits of their practice. It is altogether unimportant who discovers or makes known a process or material; it is very important that it should tfot be lost to the profession, even at the rather mortifying risk of repeating an old story. The editor acknowledges the courtesy of Dr. Samuel S. White, in tendering the free use of so many of his valuable wood-cuts. He would also express his indebtedness to the admirable treatise of Prof. Joseph Richardson for a number of very fine illustrations. To Prof. Wildman, and others, he has acknowledged his obliga- tions in the text. He submits to the Profession the Tenth Edition of Harris's " Principles and Practice of Dentistry," hoping that it will be found to meet the demands of the present advanced state of Dental Sci- ence, and that it will continue to be what its distinguished author designed it — a text-book for the student, and a useful guide and companion for the experienced practitioner. P. H. A. Baltimore, May 1, 1871- PREFACE TO THE EIGHTH EDITION. rTUIE Publishers, in preparing this, the first posthumous edi- -*- tion of the late President Harris's " Principles and Prac- tice of Dental Surgery," have spared no pains to make it in every way worthy of its own high reputation and that of its distinguished author. It has been subjected to a very thorough revision by compe- tent professional gentlemen, and will be found to contain many and important additions, bringing the work fully up to the pres- ent state of Dental Science and Art. The Publishers desire to acknowledge the valuable assistance rendered by Prof. Austen, to whom they are indebted for the entire chapter on Vulcanite, most of the chapter on Soldering, and much new matter in the chapter on Irregularity, and throughout the entire Mechanical Division of the work. They would also acknowledge important additions by Prof. Christo- pher Johnston, of the Baltimore College, a valuable section on Artificial Palates by Dr. William H. Dwindle, and a number of useful practical suggestions from Dr. Edward Maynard. The illustration of the work has been greatly improved. A few unimportant designs have been omitted; several others have been replaced, by improved drawings, and many new illustra- tions have been added, for a large number of which they are indebted to the courtesy of Dr. Samuel S. White. The Publishers lay this edition before the Profession in the confident assurance that it will be found to be what its author designed it — a thorough elementary treatise, a text-book for the student, and a useful companion and guide for the practi- tioner, xi Philadelphia, September 1, 1863. PREFACE TO THE SECOND EDITION. IN submitting to the profession a Second Edition of his Dental Practice, the author is happy to avail himself of the opportunity to express his grateful appreciation of the appro- bation which the First has received. He trusts that the additions which he has made to the primary work will make the one now presented still more acceptable. The alteration in the plan, which has resulted from the effort at improvement, has, however, rendered a slight change of title necessary, in order to express the character of the present book. In the First Edition, the Anatomy of the Mouth was omitted, because a thorough knowledge of it can be obtained from works on General Anatomy. But it has been suggested that such works may not be at hand when wanted by the dental student, and the author has thought it better to furnish a description of the several structures which enter into the formation of this cavity. He has, however, confined himself to brief expositions of the parts; not wishing to encumber the work, or distract the student with the consideration of matters foreign to the purpose for which it was written, and for which, he trusts, it will be read. He is indebted to Bourgery's Anatomy, Quain and Wilson's Anatomical Plates, Wilson's Anatomy, and Smith and Horner's Anatomical Atlas, for a number of the illustrations used in this part of the work. The Second and Fifth Parts embody the substance of two papers by the author, which wTere written subsequently to the publication of the first edition. The subjects of them came properly within the plan of the present work. The object of the author in the preparation of this edition has been to provide a thorough elementary treatise on Dental Medicine and Surgery, which might be a text-book for the student and a guide to the more experienced practitioner; and he hopes that the modifications he has introduced, and the additions he has made, will entitle it to be so considered at least, until an abler hand shall prepare a better. xii CONTENTS. INTRODUCTION. PART FIRST. anatomy and physiology. CHAPTER I. PAGE Developmemt of Cell Doctrine......................................................... 33 CHAPTER II. Anatomy and Physiology of the Mouth............................................. 46 CHAPTER III. Osteology..................................„..................................................... 47 CHAPTER IV. Bones of the Mouth and Face. Superior Maxillary....................................................................... 49 Inferior Maxillary........................................................................ 54 Palate.................................................,....................................... 56 CHAPTER V. Muscles of the Mouth and Face. Myology...................................................................................... 58 Nasal Group of Muscles................................................................ 60 Superior Maxillary Group............... ............................................ 60 Inferior Maxillary Group........................................................,...... 62 Temporo-Maxillary Group............................................................. 62 Pterygo-Maxillary Group.............................................................. 64 Lingual....................................................................................... 65 Pharyngeal................................................................................. 66 Palatal....................................................................................... 68 Soft Palate, Fauces, and Tonsils..................................................... 69 xiii XIV CONTENTS. CHAPTER VI. Blood-Vessels of the Mouth and Face. page Internal Carotid Artery......................■........................................... '0 : External Carotid Artery and Branches.............................................. <® y, Veins ...'...................................................................................... l* CHAPTER VII. Nerves of the Mouth and Face. Fifth Pair — Trigemini.................................................................. 75 Ophthalmic Branches.............................................................. 75 Superior Maxillary Branches.................................................... 77 Inferior Maxillary Branches.................................................... 70 Facial Nerve and Branches............................................................ 80 CHAPTER VIII. Salivary Glands, Tongue, Gums. Parotid Glands and Saliva.............................................................. 83 Submaxillary Glands..................................................................... 85 Sublingual and Mucous Glands....................................................... 86 Saliva from all Glands............................................................. 86 Tongue.............................................................................. ......... 87 Mucous Membrane........................................................................ 88 Gums and Periosteum................................................................... 89 Relations of the Mouth, Anatomical................................................. 90 " " Physiological............................................... 91 CHAPTER IX. The Teeth. Deciduous or Temporary Teeth....................................................... 92 Permanent Teeth —Incisors.................................................. 93 Cuspids or Canines........................................................... t_ _ 9.") Bicuspids or Pre-Molars.................................................. 9g Molars.......................................................................... 97 Articulation with Maxillae............................................... 98 Comparison of Temporary with Permanent........................... 9g Antagonism of Upper and Lower....................................... 90 Origin and Formation of Teeth..................................... jqq Goodsir on Development......................................... 1^0 Dental Pulp or Nerve...........................„,................. tqq CHAPTER X. Osseous Tooth Structures. Dentine.............................................................................. -,^9 Ennmel.......................................................................... , , _ Cementum....................................................................... ,~~ Structural Classification CONTENTS. XV PART SECOND. PATHOLOGY AND THERAPEUTICS. CHAPTER I. PAGE General Considerations............................................................,...✓... 129 CHAPTER II. Classification of Teeth.................................................................... 136 CHAPTER III. Diseases of the Mucous Membrane. Stomatitis................................................................................... 143 Erytheniatic........................................................................... 144 Ulcerative............................................................................. 145 Gangrenous........................................................................... 146 Mercurial.............................................................................. 150 Scorbutic............................................................................... 151 CHAPTER IV. Diseases of the Gums. General Considerations................................................................ 153 Inflammation, Acute and Chronic................................................... 160 Hypertrophy............................................................................... 170 Mercurial Inflammation................................................................. 172 Ulceration, with Exfoliation of Bone................................................ 175 Adhesion of Gums to Cheek............................................................ 177 Tumors of the Gums...................................................................... 178 Cystic Tumors.............................................................................. 181 CHAPTER V. Salivary Calculus. Classification of Varieties.............................................................. 193 Chemical Composition................................................................... 197 Origin and Deposition.................................................................... 198 Effects upon Teeth, Gums, and Alveoli.............................................. 200 Manner of Removing.................................................................•••• 202 Mucous Deposits upon Teeth..................................... .................... 204 CHAPTER VI. The Fluids of the Mouth................................................................. 205 CHAPTER VII. Symptomatology of the Lips............................................................. 207 XVI CONTENTS. CHAPTER VIII. PAGE Symptomatology of the Tongue.......................................................... 209 CHAPTER IX. Diseases of the Dental Pulp. General Remarks.......................................................................... 213 Irritation........................................................••••........................ 214 Inflammation................................................................................ 219 Spontaneous Disorganization........................................................... 227 Fungous Growth........................................................................... 228 Ossification..............................................................•.................. 229 CHAPTERS X. —XIV. Diseases of the Alveolar Processes. X. Periostitis......................................................................... 230 XI. Abscess............................................................................... 233 XII. Necrosis and Exfoliation................................................... 240 XIII. Absorption........................................................................ 244 XIV. Hypertrophy of Walls of Cavities...................................... 247 CHAPTERS XV.—XXII. Diseases of the Teeth. XV. Atrophy................................................................. 248 XVI. Necrosis............................................................... 255 XVII. Exostosis...................................................................... 258 XVIII. Denudation................................................................. 261 XIX. Chemical Abrasion........................................................... 264 XX. Mechanical Abrasion.................................................... 266 XXI. Fractures, and other Injuries.......................................... 267 XXII. Caries — Classification...,........,...................................... 270 Liability of Teeth to Caries...................................................... 273 Causes of Caries........................................................ n 278 Prevention of Caries................................................. 281 PART THIRD. DENTAL SURGERY. CHAPTER I. Prevention and Arrest of Caries by the Use of Files and Enamel- Chisels ................................................. 9ft. CHAPTER II. Arrest of Caries by the Operation of Filling. General Considerations......................................... Materials used for Filling................................ .............. " ' CONTENTS. xvii PAGE Gold: Non-adhesive Foil......................................................... 297 Adhesive Foil.................................................................. 298 Crystal or Sponge............................................................. 299 Tin Foil and Fusible Alloys... .................................................. 300 Amalgam............................................................................... 301 Gutta-Percha: Hill's Stopping.................................................. 302 Os-Artificiel........................................................................... 303 Formation of the Cavity ............................................................... 303 Instruments used................................ ....... .......................... 304 Rules for shaping Cavity......................................................... 309 Separation of Teeth to gain Space........................................... 311 Protection against Saliva......................................................... 313 Drying the Cavity .................................................................. 316 Filling the Cavity: Instruments used............................................... 317 Preparation and Use of Materials............................................ 319 Non-adhesive Foil: Rope and Folds..................................... 319 Redman's Cylinders.................................................... 322 Pellets...................................................................... 325 Adhesive Foil ................................................................. 325 Heavy Foil................................................................ 326 Crystal or Sponge Gold...................................................... 327 Condensation of Filling with Mallet............ ............................. 328 Finishing Surface of Filling..................................................... 329 Non-Conductors over Sensitive Pulp.......................................... 332 Filling Particular Cavities in.................................................... 334 Superior Incisors and Cuspids............................................. 334 Superior Bicuspids and Molars........................................... 343 Inferior Incisors and Cuspids............................................. 349 Inferior Bicuspids and Molars............................................. 3)1 Restoration of all or part of the Crown....................................... 355 CHAPTER III. Filling Tekth over an Exposed Nkrve............................................... 361 CHAPTER IV. Filling Pulp Cavity and Roots of Teeth. General Considerations................................................................... 36/ Destruction and Removal of Pulp.................................................... 3/0 Preparation of Cavity and Root...................................................... oio Operation of Filling .................................................................. • °" CHAPTER V. Causes and Treatment of Odontalgia................................................ 3(9 CHAPTER VI. Extraction of Teeth. General Remarks......................................................................... 386 xviii CONTENTS. PAGE indications for Extraction.............................................................. 387 Instruments................................................................................. 389 Key of Garengeot................................................................... 389 Manner of Using.............................................................. 391 Forceps: Various Forms.......................................................... 392 Manner of Using............................................................... 401 Extraction of Roots..................................................................... 404 CHAPTER VII. Use of Anaesthetics in Extraction. General Anaesthesia by Ether......................................................... 410 Chloroform....................................,........................................ 410 Nitrous Oxide.........*.............................................................. 412 Other Anaesthetics.................................................................... 414 Local Anaesthesia by Cold............................................................... 415 Electro-Magnetism................................................................... 417 Spray Apparatus.................................................................... 418 CHAPTER VIII. Irregularity in Development anjd Arrangement of the Teeth. . General Considerations.................................................................. 420 Abnormal Formation and Growth...................................................... 421 Osseous Union of Teeth............................................................... 422 Supernumerary Teeth............................................................. 424 Third Dentition......................................................................... 425 Method of Directing Second Dentition.................................................... 430 Abnormal Arrangement.................................................................. 434 Treatment of Irregularity........................................................ 436 Excessive Development of Lower Teeth............................................ 450 Protrusion of Lower Maxilla.......................................................... 452 CHAPTER IX. Dislocation and Fracture of the Jaw.................................................... 454 CHAPTER X. Diseases of the Maxillary Sinus...................................................... 460 PART FOURTH. DENTAL MECHANISM. Classification of Operations—........................................................ 485 CHAPTER I. Prosthesis of Dental Organs............................................................. 488 CONTENTS. xix CHAPTER II. Substances used as Dental Substitutes. page Human Teeth.................,......................................,..................... 491 Teeth of Cattle............................................................................. 492 Elephant and Hippopotamus Ivory.......,.......................................... 493 Porcelain, or Incorruptible Teeth..................................................... 494 CHAPTER III. Different Methods of Inserting Teeth. Placed upon Natural Roots...............................................—......... 495 Secured by Clasps........................................................................ 497 Retained by Spiral Springs............................................................ 499 Held by Atmospheric Pressure........................................................ 500 CHAPTER IV. Preparatory Treatment of the Mouth.............................................. 503 CHAPTER V. Preparation of Natural Root and Attachment of Artificial Crown... 507 CHAPTER VI. Refining and Alloying Gold and Calculating Fineness of Gold Plate. Quality of Gold for Plate................................................................ 521 Refining Gold............,.................................................................. 523 Alloying Gold...........................................................................,.... 528 Calculating Fineness of Gold Plate.............,................... „,.............. 530 CHAPTER VII. Gold Plate, Spiral Springs, Gold Solder. Ingot Moulds................................................................................ 532 Rolling Mills................................................................................. 533 Gauge- and Draw-Plates................................................................ 535 Gold Solder................................................................................. 536 CHAPTER VIII. Cups and Materials for Impressions of the Mouth.—Plaster Models. Impression Cups........................................................................... 538 Impression Materials.................................................................... 541 Comparative Value.................................................................. 547 Plaster Models............................................................................. 549 CHAPTER IX Metallic Dies and Counter-Dies. — Process of Swaging. Methods of Making Dies and Counter-Dies....................................... 556 Metals used for Dies and Counter-Dies................................................ 561 Processes of Swaging.*................................................................... 566 CHAPTER X. Articulation, or Antagonism of Teeth................................................ 571 XX CONTENTS. CHAPTER XI. Principles and Appliances of Soldering. page Principles of Soldering.................................................................... 577 Soldering Lamps.......................................................................... 578 Blowpipes : Mouth........................................................................ 579 Self-acting............................................................................ 580 Mechanical..................................,......................................... 581 Hydrostatic........................................................................... 585 Other Appliances of Soldering........................................................ 587 CHAPTER XII. Adjustment of Porcelain Teeth to the Plate. — Finishing Process. Varieties of Porcelain Teeth............................................................. 589 Dental Lathes.............................................................................. 590 Grinding and Arranging Teeth........................................................ 593 Investing and Backing Teeth.......................................................... 596 Soldering Backings to Teeth and Plate............................................. 601 Finishing Process......................................................................... 603 CHAPTER XIII. Retention of Base-Plates in the Mouth. — Their Size and Form of Out- line.— Materials of Swaged Pl-ates. — Continuous-Gum Work. Different Methods of Retention....................................,.................. 605 Spiral Springs.................................... .................................. 606 Clasps: Utility and Application................................................. 607 Shape and Adjustment....................................................... 610 Partial Clasps or Stays...................................................... 614 Size and Outline of Clasp-Plates.......................................... 615 For Upper Incisors..................................................... 616 For Upper Bicuspids................................................... 618 For Alternate Spaces.................................................. 620 Atmospheric Pressure Principle ............................................... 622 Adhesion of Contact.......................................................... G25 Vacuum Cavity................................................................ 628 Various Materials of Swaged Plates................................................ 632 Continuous-Gum Work.................................................................... 633 CHAPTER XIV. Moulded Plates, or Plastic Work. — Ceramo-Plastic Work. Classification of Plastic Work......................................................... 640 Comparison of Varieties................................................................. 641 Ceramo-Plastic Work.................................................................... 642 CHAPTER XV. Metallo-Plastic Work.—Vulcano-Plastic Work. Tin and its Alloys........................................................................ g43 Cheoplastic Process............................................................. g,j<- S'anno-Plastic Process....................................................... gc« Aluminum..........................................'................................. ,.-o Alumino-Plastic Process............................... er.n ......................................... bbkj Refining Aluminum............................................................. „-? CONTENTS. xxi PAGE Vulcano-Plastic Work............................................................ gyg Corallite...................................................................... gyg Vulcanite : History.................................................. gjg Composition and Varieties...................................... C50 Effect of Vermilion....................................... (,^] Vulcano-Plastic Process: Impressions......................................... 682 Models and Articulators..................................................... 683 Selection and Arrangement of Teeth..................................... (385 Vulcanizing Flasks.............................................................. 688 Forms of Flask............................................................... U'f FORMATION OF PUS. To illustrate the change In Rcrra\nal matte, of an Eoithelial cell, resulting from increased nutrition, showing the manneria which the germinal matter c. a normal cell, if supplied freely with pabulum, may jive nse to pus. Fig.U. Fig. it. «ff-«• Mil li'i'iR' - Young. Fullyfonr-'l Young. Fully formed. TEXDOX. CARTILAGE. a, Sarcolemma. o, Contractile matter. MUSCLE. Fig. iS, The arrow matter is jhows the direction in which germinal supposed to be moving nkrvk. Development of young, dark -bordered nerve fibres, nt an early period, showing gtrmiu '. matter and formed material of elemeutary parts. X 1800. Fig. n. New centre or nucleolus. <$$£*£& ■ ■'';'■ JtMOTBA. Pure germin.j natter. X5000. "| Gtrruimdi Oldest part of formed material. Yonnr»*st part ot formed material. Coarse of jmKilum PLATE ILLUSTRATING DE. BEALE'S VIEWS. F'vvi Tuaon'e Cell Doctrine. B$B THE PRINCIPLES AND PRACTICE OF DENTISTRY. CHAPTER I. DEVELOPMENT OF THE CELL DOCTRINE. THE point of departure in the study of anatomy and physiology, of all the phenomena of life, indeed, is the cell; and so general is the attention now directed to this point of investigation by scientific and learned men of all classes, that no work, professing to treat of physiology, can be considered complete that does not, at least, give an epitome of the most popular views on the subject of cell constitution and cell growth. Before directing attention to that theory which, in the opinion of the writer, seems most worthy of acceptance, we propose, therefore, to give a very brief exposition of the state of scientific in- formation on this subject, together with a statement of those investiga- tions that have finally culminated in the present accepted views; and then, with as much brevity as is compatible with clearness, state that doctrine which seems to embody most of truth, without pausing to consider the objections that may have been brought against it. In 1670, Malpighi recognized the blood corpuscles, and" elaborately in- vestigated the cell structure of plants, to which Robert Hook had called attention, 1667. He showed that the "cells," or "vesicles," were separable, that each " cell" was an independent entity, to which he gave the name "utriculus." In 1687, the blood corpuscles were well described by Leuwenhoeck, who also discovered the spermatozoids, which he believed to be sperm animals of distinct sexes. Haller was, however, the first to attempt to construct the tissues by the association of their ultimate anatomical elements. His elements were the " fibre'* 3 33 34 DEVELOPMENT OF THE CELL DOCTRINE. and an " organized concrete," the ofiice of the latter being simply to bind the fibres together as a glue. Wolf, in 1759, advanced the theory, that in a clear viscous fluid without organization of any kind, cavities were developed, which, if rounded or polygonal, became cells; if elongated, vessels; and that the law was the same for both plants and animals, except that in the plants the cells were finally separated from each other, whilst " in the animals they always remained in com- munication. In each case they are mere cavities, and not independent entities; organization is not effected by them, but they are the visible re- sults of the organizing power inherent in the living mass, or what Wolf calls the vis essentialis." * Haller's doctrine continued, however, to main- tain ascendency until near the close of the eighteenth century, when it gave place to the "globular" theory, originally advanced by Leu- wenhoeck in 1687, but which had attracted little attention at that time. Near the close of the eighteenth century, quite a formidable array of great names are associated with it. The term " globule," understood by most writers of this day to mean a spherical body, with a dark out- line and a bright centre, was then used indiscriminately with granule and molecule, which are now commonly held to be bodies of inde- terminate shape, though Virchow and other German writers sometimes use them as convertible terms. " Prochaska, in 1779, described the brain as made up of globules eight times smaller than blood globules. In the year 1801, the philosophic mind of Bichat elaborated his ex- cellent classification ; but he seems to have made no original investi- gations in minute structure, or to have adopted any special theory of an ultimate physical element. The brothers Joseph and Charles Wenzel, in 1812, described the brain as composed of globules of small size. Among the earliest histologists worthy of mention is Treviranus, whose elements, according to Henle, were first, a homogeneous, form- less matter; second, fibres; third, globules (Kiigelchen). Mr. Bauer, quoted as a most experienced microscopic observer by Sir Everard Home, in 1818, and again in 1823, describes the ultimate globules of the brain, and of muscular fibre, as of the size of a globule of blood deprived of its coloring matter, or about ^^ of an inch in diameter. The fibre was excluded as an ultimate element of organization by Heusinger in 1822-4, who started all tissues from the globule, still, however, retaining the formless material of Haller and Treviranus. Heusinger formed the fibre by the linear apposition of the globular elementary parts, and even explained how canals and vessels were formed by a similar arrangement of vesicles which had originated from the globules."f Milne Edwards must be credited more than Huxley, as quoted in Tyson's Cell Doctrine. f Tyson's Cell Doctrine 23. DEVELOPMENT OF THE CELL DOCTRINE. 35 any other writer with the establishment of the globular doctrine. He held that all tissues, both animal and vegetable, were formed by the aggregation of globules. Baumgartner and Arnold maintained a somewhat similar doctrine. Dr. Hodgekins showed the fallacy of Ed- ward's view, and the globular theory began to lose ground except in the more limited sense of " granule." Dr. Robert Brown, in 1833, discovered the nucleus, though he seems not to have appreciated its importance. Raspail, in 1837, tells us that development takes place from "cells" or vesicles, capable of indefinite multiplication, endowed with life, and capable of absorbing oxygen, and of spherical form ; that the cell is made up of atoms crystallizing about an ideal centre, the cell being represented by the crystal rather than the atoms of which it was composed. Dutrochet held that the solids and fluids of the body were alike composed of cells; that in the solids they were more closely attached, while in the liquids they moved freely, whilst other structures, also composed of cells, were difficult to refer either to the solids or liquids. Animal fibres he considered made up of elon- gated cells, and that vegetable structures were formed on the same general plan. After the discovery of the nucleus by Dr. Robert Brown, it was observed by quite a number of investigators, among whom were Valentin, Purkinje, Turpin, Schultze, Rudolph, Wagner, and Henle, most of whom had observed the development of cells about a pre-existing nucleus; and Valentin had traced in the nucleus of epidermic cells a resemblance to the nucleus of vegetable cells, and had shown in the crystalline lens, and in muscular fibre, the develop- ment of fibres from cells, while Quatrefages and Dumourier had ob- served the origin of young cells from old in the embryo of the snail, all before the appearance of Schleiden's work. To Schleiden is due the credit of first establishing (1838) a uniform system of cell de- velopment in vegetable structures, of which the cell was the unit, and to Schwann the extension of the theory to animal structures. To the nucleus Schleiden gives the name " cytoblast," or cell germ. He also calls attention to the nucleolus, which he thinks is formed before the cytoblast. "The entire growth of the plant," says he, "consists only of the formation of cells within cells." Schwann applied Schlei- den's theory of vegetable growth to animal tissues. The nucleolus is first formed in a granular or structureless cytoblastema, and around it is deposited a substance, granular or structureless, in which new mole- cules are deposited between those already formed around about the nucleolus, thus forming the nucleus. When this deposition " goes on equally throughout the entire thickness of the stratum, the nucleus may remain solid; but if it goes on more vigorously in the external part, the latter will become more dense, and may become hardened 36 DEVELOPMENT OF THE CELL DOCTRINE. into a membrane, and such are the hollow nuclei."* After reaching a certain stage, there is deposited about the nucleus a stratum of sub- stance, differing from the cytoblastema, by which the complete cell is formed. This substance may be either homogeneous or granular, more frequently the latter. At first the cell wall and cell cavity cannot be distinguished from each other; but as the deposition continues, the cell wall becomes denser and more clearly defined, until the external layer, when the stratum is thick, or the entire stratum, when it is thin, becomes consolidated into a membrane, whilst many cells that seem to be continuously solid, present only a little greater density on the surface. After the formation of the membrane it continues to grow by the continued deposition of new molecules between the pre-existing ones, becoming, at the same time, separated from the nucleus; the space thus left subsequently becomes filled with fluid. Thus, Schlei- den and Schwann seem to have anticipated most of what is now known in reference to tissue formation from cells, whilst differing con- siderably from present theories concerning the growth of the cell itself, and the situation of its nucleus, which they placed near the cell wall, while most writers of the present day place it centrally, though not uniformly so; nor do more recent writers hold that either the cell wall or nucleus is essential to the ultimate anatomical element, as was held by them. Henle, in 1841, recognized three modes of cell forma- tion,—budding, endogenous growth, and segmentation, — which latter had been denied by Schleiden and Schwann ; nor did he seem to recog- nize the nucleus as an essential part of the cell. Richart, in 1840, failed to find it uniformly present. Karsten, in 1843, stated " that cells originate without a pre-existing nucleus, and by the expansion of amorphous granules of organic matter." Kolliker, in 1844, dissented from the idea of a single method of cell formation, and Mr. Paget, in 1846, " declared that cells might arise in some other way than from a nucleus." In 1841, Dr. Martin Barry writes,f "I am very much in- clined to believe that in the many instances in which authors on ' cells have described and figured more than one nucleolus in a nucleus, there has been either an apparent division of the nucleus into discs, or the nucleus has consisted of two or more discs ; the nucleoli of those authors have been the minute and highly refracting cavities or depressions in the discs. If this has really been the case, it affords additional evidence, I think, that reproduction of cells by the process I have described, namely, division of the nucleus of the present cell, is universal, so numerous have been the instances in question.' .... The nuclei which various ob- servers have found lying among the fibres of various tissues, have * Schwann, as quoted by Tyson, p. 43. f Philosophical Transactions for 1841, pp. 207, 208. DEVELOPMENT OF THE CELL DOCTRINE. 37 been considered by them as the 'remains of cells.'1 This may have been the case; but so far from thinking, with those observers, that the nuclei in question were ' destined to be absorbed,' I am disposed to consider that they are sources from which would have arisen new cells." In 1845, Prof. John Goodsir published a paper on "Centres of Nutrition," in which is embodied the two most important facts in the cell doctrine of this day, viz.— the activity of these centres (nuclei), the manner in which they derive nutriment from the capillaries or other sources, distributing it " by development to each organ or tex- ture after its kind," and the development of all such centres from pre- existing centres or nuclei.* "As the entire organism is formed at first, not by simultaneous formation of its parts, but by the successive development of these from one centre, so the various parts arise each from its own centre, this being the original source of all the centres with which the part is ultimately supplied." Thus, not only does the whole organism consist of " simple or developed cells," with an inde- pendent vitality, " but that there is in addition, a division of the whole into departments, each containing a certain number of developed cells, all of which hold certain relations to one central or capital cell, around which they are grouped. It would appear that from this central cell all the other cells of its department derive their origin. It is the mother of all those within its own territory." He divides these centres of nutrition into two kinds —those that are "peculiar to the textures, and those that belong to the organs." The former are generally perma- nent, whilst the latter last only during embryonic life, and finally dis- appear or "break in the various centres of the textures of which the organ is composed." "A nutritive centre, anatomically considered, is merely a cell, the nucleus of which is the permanent source of successive broods of young cells." Prof. Huxley taught, in 1853, that vitality was " a property inherent in certain kinds of matter," and that there is a condition of all kinds of living matter, in which.it is simply an amorphous germ, possessing no structure, its external form depending . exclusively on physical laws, and that the successive differentiations or changes of this amorphous mass will depend on previously existing conditions. This differentiation may be of two kinds, in "unicellular organisms" it is "external;" that is, is concerned only in the shape of the organism, without reference to any internal structure; but in all higher organism the external differentiation is preceded or accom- panied by an internal change, and the "homogeneous germ" is con- verted into a central portion or endoplast and a peripheral or periplast, thus constituting the germ a vesicle with a nucleated centre. He said there was " no evidence whatever " that the vital forces were resident * Tyson, p. 46. 38 DEVELOPMENT OF THE CELL DOCTRINE. exclusively in either the endoplast or the periplast, or that they exerted any attraction over each other; that though they were in harmony, the changes which they subsequently underwent had no " causal con- nection." That the endoplast, so far from being the seat of especial vital action, underwent no morphological change whatever, except growth and division, while the periplast was the subject of the most important metamorphic changes, morphological and chemical; by its differentiation all the various tissues are produced through molecular changes in its structure, under the guidance of the vital force. This metamorphosis of the periplast is of two kinds, " chemical and struc- tural,"— the former may consist in "conversion," as of cellulose into xylogen, etc., or in "deposit," as of earthy matter in the bone of ani- mals, and in plants. The peculiarities of Prof. Huxley's doctrine at that time were the substitution of the term "endoplast" for "nucleus," "periplast" for "cell wall;" the perfectly passive nature of the "endoplast" as well as of the periplast, so far as the determination of change was concerned, though itself the seat of very active change. He also held that the "vital phenomena are not necessarily preceded by organization, nor are in any way the result or effect of formed parts, but that the faculty of manifesting them resides in the matter of which living bodies are composed as such; or, to use the language of the day, that the vital forces are molecular forces." He also denied the invariable presence of the nucleus, and believed that all cell development occurred by division, except in some vegetable organism which he specified. Dr. J. Hughes Bennett also held that the "ultimate parts of organi- zation" were not "cells " or "nuclei," but the "molecules" of which they were formed; and that these molecules, by virtue of some " independent physical and vital property " were enabled to unite so as to form the various tissues. To these molecules he gives the names " histogenetic," or " tissue forming," and " histolytic," or disintegrative. With him the first step in organization is the formation of an " organic fluid," and the precipitation therefrom of "organic molecules," from which, ac- cording to the molecular theory, " all textures are derived." He is also an advocate of spontaneous generation, and " admits the produc- tion of cells by buds, division or proliferation, without a new act of generation." As late as 1856, Messrs. Todd and Bowman are found advocating the free-cell formation theory of Schleiden and Schwann. They say, taking up the ovum after fecundation, " at this period the embryo consists of an aggregate of cells, and its further growth takes place by the development of new ones. This may be accomplished in two ways : first, by the development of new cells within the old, through the subdivision of the nucleus into two or more segments and the forma- DEVELOPMENT OF THE CELL DOCTRINE. 39 tion of a cell around each, which then becomes the nucleus of a new cell, and may in its turn become the parent of other nuclei; and secondly, by the formation of a granular-deposit, between the cells, in which the development of the new cells takes place. The granules cohere to each other in separate groups here and there, to form nuclei, and around each of these a delicate membrane is formed, which is the cell membrane. The nuclei have been named cytoblasts, because they appear to form the cells; and the granular deposit in which these changes take place is called cytoblastema." * In one of these ways, according to these observers, all cells are formed; the precise manner in which the tissues are formed from the cells, they declare themselves unable to state. The probable changes which occur in the cell, they describe under two heads,— those that take place in the cell membrane and those that take place in the nucleus. In all real or apparent fibrous structures, as " areolar and fibrous tissues, the cell membrane becomes elongated," and gives the appearance of being divided into minute fibres; in the tissues which are composed of homogeneous tubes filled with a peculiar substance, the cells become attached end to end, the partition is absorbed, and the tube formed in which is deposited the proper nerve or muscular substance. The capillaries are likewise formed by the coalescence of the cells at many points by pointed processes which are given off from them. Dr. Carpenter also gives in detail the mode of free cell development as " one of two principal modes " in which cells "may originate," whilst at the same time he declares himself an advo- cate of the views entertained by Dr. Lionel Beale. Prof. Virchow, on the other hand, in his " Cellular Pathology," published in 1858, states that cells can only originate from pre-existing cells, and describes the typical cell as consisting of "cell wall," "cell contents," nucleus, and in the fully developed cell, usually a " nucleolus," though it is not essential. Later, he is reported as holdingf "that a nucleus surrounded by a molecular blastema was sufficient to constitute a cell;" the " cell wall" being unessential. The cell he considers the centre of activity beyond which life cannot be removed, and from it proceed all physiological and pathological processes, and though each cell is an independent centre of vitality, yet as they are necessarily associated in the construction of vari- ous tissues, they are in so much mutually dependent; and as they are severally associated for the attainment of particular ends, he divides them into certain districts or "cell territories," as previously taught by Good- sir, the intercellular substance deriving peculiar properties from its par- ticular association. On the nucleus, according to this writer, depends the * Todd and Bowman, Physiological Anatomy, p. 63, Amer. Edit., 1857. ■j- Tyson's Cell Doctrine, p. 61. 40 DEVELOPMENT OF THE CELL DOCTRINE. life of the cell, while to the cell contents over and above the nucleus belongs the fuuction of the structure, neurility, contractility, secretion, for nerve, muscle, and gland -respectively. Nor does he believe in the so-called effusions, holding rather that all plastic deposits are the result of excessive cell proliferation of the tissue concerned, and are not an effu- sion from the blood, as is thought by Beale; nor does he except even fibrin found external to the bloodvessels. Another peculiarity of his doctrine is — not as Schleiden and Schwann taught, and as is generally believed, that all tissues healthy or morbid result from the apposition of cells — that all physiological and pathological growths result from a particular cell, the cell of the connective tissue; from it are formed muscular and nerve fibres, and by the too rapid proliferation of these cells pus is formed, and by their perverted growth tubercle, cancer, and all morbid growths; though he admits that pus may also be formed in the develop- ment of epithelium, either of mucous membrane or cuticle; and lastly, he supplements the lymphatic and capillary systems by a peculiar system of tubes or canals, resulting from the anastomosis of one cell with another, which he classes with the great canalicular system, and to it refers the "cord-like fibres of yellow elastic tissue," which he thinks originate in the connective tissue corpuscle. Singularly enough, after stating that every tissue is formed from cells, he says, that " pure white fibrous tissue does not have its origin in cells, but is a modifica- tion of a previously homogeneous intercellular substance, deposited between the cells.* Dujardin, in 1835, discovered a moving substance, to which he gave the name " sarcode," in the lower animals, which was thought by Huxley, Meyer, Schultze, and Miiller, to be peculiar to them, and possessed of " irritability without nerves." Siebold observed similar movements in the yolk globules of planaria, which led Kolliker to suppose that all cell contents were contractile. Virchow thought these movements due to a contractile substance, Leydig thought them phenomena of life, but all believed them to be " something different from the animal cell, as a body sui generis." Prigsheim, in 1854, declared the entire vegetable cell contents to consist of protoplasm and fluid, and denied the existence of a primor- dial utricle, though admitting that the protoplasm a might be arranged in layers, but that these layers could .not be distinguished as a distinct membrane. Leydig, in 1856, denied the existence of a cell wall and believed what was held to be it was but the hardened periphery of protoplasm, which, together with the nucleus, constituted the cell Schultze, in 1861, " defined the cell as protoplasm enclosing a nucleus " " The cell," he says in 1863, " leads in itself an independent life of which the protoplasm is especially the seat, although to the nucleus' also un- * Tyson's Cell Doctrine, p. 69. DEVELOPMENT OF THE CELL DOCTRINE. 41 doubtedly falls a most important though not yet precisely determined role. Protoplasm is for the most part no further distinct than that it will not commingle with the surrounding medium, and in the pecu- liarity that with the nucleus it forms a unit. Upon the surface of the protoplasm there may form a membrane, which, although derived from it, may be chemically different, and the assertion that it is the beginning of a retrogression may be defended."* Briicke had previously (1861) shown that the nucleus even was not an essential part of the cell, and there has been cited in evidence the non-nucleated amoeba and protozoon, and two non-nucleated monads described by Cienkowsky. We come now to the consideration of that doctrine which seems to us to embody the great- est amount of truth, and to be capable of explaining the greatest number of the phenomena of life — a doctrine that has been slowly evolved by the labor of scientists everywhere: many of the ideas entering into it had been suggested by other investigators; but Dr. Lionel Beale — who, more than any other investigator, has more fully elaborated, and more wisely associated the facts on which it is based, whilst adding largely to them by his own investigation — is generally recognized as the exponent of that doctrine of cell organization and growth which claims a "vital" influence as an essential factor in the resolution of the problem of life — a doctrine to which we give our most unqualified adherence. Dr. Beale makes some very important and advantageous alterations in the old nomenclature; he describes the cell, or, as he prefers to call it, " elementary part," as consisting essentially of " ger- minal matter" and " formed material." " Germinal matter" represents what was known to former writers as "cell contents," "protoplasm," "endoplast," and "nucleus." It is the living, growing part of the cell — that part which appropriates the pabulum brought to it by the blood, and with it reconstructs itself, continually repairing the waste resulting from disintegration of "formed material," the latter cor- responding to the "cell wall," primordial utricle, "periplast," and "intercellular substance;" the germinal matter is centrally situated, the formed material superficially, and results, Dr. Beale thinks, from the death of the germinal matter, and this is the single feature of his doc- trine to which we are disposed to take exception. We do not see with what propriety the formed material is spoken of as " dead," whilst still invested with the properties of life, contractility in muscle, neurility in nerve, etc., as has been well objected by Dr. Tyson, though Dr. Beale himself does not seem to look upon contractility and neurility as vital phenomena. "I might go farther than many of those who adopt the physical theory of life, and admit that not only muscular and nervous action, but that the production of many of the compounds * Schultze, Protopl. d. Rhizopoden. 42 DEVELOPMENT OF THE CELL DOCTRINE. found in the secretions and in the blood are due to physical and chemical changes alone."* To me the function of the different struc- tures seems quite as wonderful, and as inexplicable on purely physical laws as their formation; and indeed Dr. Beale seems to have an uneasy sensation that something more than physical law is involved in mus- cular contractility, for a little further on he says: " No one knows better than the physicist, that the force of muscular contraction very far exceeds that which can be obtained from any known arrangement containing the same weight of matter." f Nor do any of the phenom- ena of life seem more remarkable to me than sensibility, and the power of originating sentient motion, which latter is surely quite as wonderful as that living particles should move from a centre in opposition to the general law of all purely physical motion, not to mention the higher intellectual acts to which the application of the term nerve-function may not be recognized as appropriate. The essential features of this theory are that all structures "spring from pre-existing structures" which are capable of appropriating to themselves things differing from themselves, and converting them into structures identical with them- selves, and further, that they are capable of indefinite multiplication. No such thing, therefore, as spontaneous generation does or can occur. Germinal matter is of "granular appearance," and is everywhere the same; the germinal matter of nerve tissue cannot be distinguished from the germinal matter of a leaf or of the lowest fungus. All ger- minal matter was once pabulum, as all tissues were once germinal matter. The formed material, or cell wall when it exists, is of vari- able thickness, and may continue to increase in thickness by the formation from the germinal matter of new material on its inner sur- face, or it may become thinner by the rapid accumulation of germinal matter within, and its consequent distention; or both .nay take place at the same time, the cell wall remaining passive. The formed mate- rial endowed with such properties as contractility in muscle is yet incapable of reproducing itself by the assimilation of pabulum, whilst the germinal matter is the laboratory where, under some inexplicable guidance, the inert elements of the tissues, brought thither by the blood, are converted into living matter. Situated in the centre of the elementary part, all food must pass through the formed material to reach the germinal matter; hence the growth of the cell will be more or less rapid, other things being equal, according to the thickness of the formed material, the most superficial and oldest part of the cell. The form of the particles of germinal matter is, in Dr. Beale's opinion, spherical, though he acknowledges * Structure and Growth of Tissues, p. 211 f Ibid. p. 213. DEVELOPMENT OF THE CELL DOCTRINE. 43 that such a conclusion is purely conjectural, since it is impossible to see them separately or even to conceive a particle of living matter not compound. The nutritive changes in the tissues depend for their proper activity on the two opposite processes of disintegration and renewal; as new particles are constantly being added by the assimilative action of the germinal matter, so waste is constantly taking place by destructive metamorphosis of the formed material, and in the maintenance of a perfect equilibrium between these processes consists the health of the part; but if the blood be charged with some poisonous element impair- ing the nutritive qualities of the cell food, or if the blood be deficient in healthy pabulum, from indigestion or improper quality of ingesta, or if the quantity of the blood circulating through the part prove inadequate to its proper support, this equilibrium is destroyed and disease results. " A change of this sort occurs in scarlet fever. The morbid matter circulating in the blood interferes with the regular pro- duction of new cuticle; for a time none is formed, but by and by, when the violence of the disease abates, and the poison is in a great measure eliminated from the blood, the formative process is re-estab- lished. A gap, however, exists, as it were, between the tissue formed before the interference of the disease, and that produced after the natural process was resumed. In point of age they are separated by an interval, so that as the new cuticle grows up from below, the old is separated en masse." Though the germinal matter is everywhere the same in general appearance, and grows in precisely the same way, yet the structure resulting from its growth is very different according to the situation from which it is derived ; the germinal matter of muscle will form nothing but muscle, that of nerve nothing but nerve; it is seen therefore to possess peculiar endowments according to the locality in which it originated, though all these structures are known to have had a common origin " from a single mass in the embryo." Nor is this peculiar endowment lost by transplantation; in whatever situation the cell may subsequently be found, if it grow at all, it does so in obedience to the impulse received from the parent cell, refusing to acknowledge any formative control from the structure by which it may be invested. The germinal matter of bone will produce bone wherever it may be placed, if the conditions requisite to its growth and development be preserved. Dr. Beale thinks "bone cancer" is an illustration of this fact; and that it is due to the escape into the blood of minute particles of germinal matter from bone, which is subsequently deposited in some tissue where conditions favorable to development exist, and thus is formed, in an abnormal situation, an osseous growth. Virchow's theory that all pathological growths are the result of exces- 44 DEVELOPMENT OF THE CELL DOCTRINE. sive proliferation of the connective tissue corpuscle in the situation in which it is found, fails to account satisfactorily for such phenomena as these. On considering the changes that take place after the applica- tion of a blister, we shall be able to observe the formation of pus globules and the development of cuticle,— after the application of the irritant, a fluid is poured out between the layers of the cuticle; upon the deep surface of the superficial layer are seen little masses of germinal matter enveloped in a thick layer of formed material, in the subjacent fluid also after a time will be found a great number of these elementary parts, with however a comparatively thin layer of formed material, rapidly multiplying. These are pus corpuscles which are observed to have the power of appropriating the nutrient material of the blood and the debris of the tissues, and of converting it into material like them- selves. This takes place much more rapidly than in the normal state. The nutritive material is furnished in greater abundance than usual, and if it were not so converted, it would undergo decomposition, and the whole of the surrounding tissue would be destroyed. Here the elementary part of cuticle is formed in the usual way, but too rapidly for the low conversion of germinal matter into the tissue of cuticle; a soft, spongy matter resembling cuticle is formed, which cannot undergo further formative transformation, but becomes pus instead. In the process of healing, the reverse of this takes place: a layer of formed material is slowly formed on the surface of the ele- mentary parts, which are no longer produced with such rapidity, and is gradually converted into proper cuticular tissue. The relative pro- portion of germinal matter to formed material is much greater in young tissue than in old; in youth than in the adult. The development of tissue takes place rapidly in the embryo, where the germinal matter is abundant, in old age it progresses slowly, owing to the proportionately small quantity of germinal matter to the formed material, which so envelops it as to obstruct the passage of nutrient matter to it. In the fluids of the body we find germinal matter abundant in " the white corpuscles of the blood, the corpuscles of the lymph and chyle, and the contents of the closed glands are to be regarded as masses of germinal matter possessing important powers of growth." * In certain diseased conditions the white blood corpuscles undergo very rapid development, whilst their further change into red blood corpuscles takes place very slowly, thus destroying the balance between disintegration and repair. " Chyle and lymph corpuscles, certain corpuscles in some specimens of mucus, the corpuscles in certain glandular organs, white blood cor- puscles, and pus globules," bear an exceedingly close resemblance to each other for a very obvious reason; they are composed almost en- * Beale On the Structure and Growth of Tissues, p. 48. DEVELOPMENT OF THE CELL DOCTRINE. 45 tirely of germinal matter; and we have seen that germinal matter is the same in appearance wherever found, though possessed of very dif- ferent powers, according to its origin. The white blood corpuscles are purely germinal matter, which Dr. Beale thinks would undergo de- velopment into tissue, if it were not for the constant motion to which they are subjected, and that when, from any cause, they become sta- tionary, they undergo rapid conversion into some simple form of fibrous tissue; " indeed, there is reason for believing that fibrin is the formed material of the white blood corpuscles." * Secretion, according to Dr. Beale, is the resultant of the disintegration of the secretory organ; thus, in the liver this process is described as a transudation from the blood of the material of which the bile is composed, which becomes converted into the germinal matter of the liver cell. " The particles of this mass are constantly growing from centre to circumference, and when they have reached the circumference of the mass, having passed through various stages of their existence, they become bile." The general theory of development, as taught by Dr. Beale, is briefly summed up by himself in the following words: "1. Matter which pos- sesses the power of forming itself into, or of altering the arrangement and relation of, its own constituent elements so as to form matter having cer- tain peculiar properties. 2. Matter or tissue which has thus resulted or been formed. The latter generally forms an investment around and protects the former; but in certain cases, besides this investment being formed, some of the living particles undergo change, and become re- solved into a peculiar formed matter, of which very little remains, is found between the external investment and the peculiar formed matter within. As examples of this, you may remember I adduced the familiar examples of the fat cell and the starch cell. In nutrition, the pabulum first becomes forming matter, and in this new state passes through certain stages of existence, and at last becomes formed. The movement of the particles always takes place in one constant direction from the centre, at which they become living. The pabulum always passes in the opposite direction." * Beale On the Structure and Growth of Tissues, p. 49. 46 ANATOMY AND PHYSIOLOGY OF THE MOU CHAPTER II. ANATOMY AND PHYSIOLOGY OF THE MOUTH. THE mouth signifies, in the human subject, the space included be- tween the palatine arch above, the mylo-hyoid muscles beneath, the lips in front, the velum palati behind, and the cheeks on either side. The teeth and closed jaws separate the inner portion, or lingual cavity, from the outer, or vestibular space; and while that part of the latter bounded by the cheeks ought properly to bear the appellation buccal, the term buccal cavity is not unfrequently employed with a significa- tion so general as to comprehend the whole oral cavity. In the mouth are the tongue, teeth, and the alveolar ridges invested by the gums: into it are poured the secretion of the parotid, sub- maxillary and sublingual glands, as well as that of the ordinary mucous and of the special lingual follicles; and in it the food is sub- jected to the processes of mastication and insalivation previous to deglutition. It is farther concerned in the prehension of aliment; and besides containing the organs of taste, is employed in articulation, expectora- tion, suction, etc. The parts concurring to constitute the mouth form a very compli- cated piece of mechanism ; through them it has a wide range of sym- pathies, and by them it performs a great variety of functions. The anatomical elements composing these parts consist of Bone- Ligament, Muscle, Gland, Bloodvessel, Nerve, Areolar, and Adipose tissues, and Mucous membrane. These different elements combine together and form the various organs which constitute the mouth. These organs I shall consider in their physiological order: thus combining their anatomy and physiology, studying at the same time both their healthy structure and function. OSTEOLOGY. 47 CHAPTER III. OSTEOLOGY. BONE is one of the hardest substances in the body. It is composed of animal or organic matter in intimate association with earthy, or inorganic matter. From the organic matter the bone derives the properties of toughness and elasticity; and from the earthy material, hardness and solidity. The mineral matter may be dissolved out by a dilute solution of nitric or muriatic acids, whilst the animal matter remains unaffected, retaining its form, though loosing its hardness, so that the long bones, so great is their flexibility, may be tied into a knot; on the other hand, by subjecting them to a high heat in an open fire, whilst exposed to the air, the animal matter may be consumed, leaving the mineral to preserve the form of the bone, but so insecurely that it will crumble to ashes in the grasp of the hand. The composition of bone, according to Berzelius, is about one-third animal and two-thirds mineral matter: Animal Matter, Gelatin and Bloodvessels, .... 33-30 "] Phosphate of Lime,......51-04 Inorganic Carbonate of Lime,.....11-30 or [ Fluoride of Calcium, . . . . . 200 Earthy Matter. Phosphate of Magnesia, . . . . 116 J Soda and Chloride of Sodium, . . .1-20 The proportion of earthy and animal matter is generally thought to vary with varying age. According to Shreger, this difference is as follows: CHILD. ADULT. OLD AGE. Animal Matter, . . 47-20 . . 20-18 . . 12-2 Earthy Matter, . . 48-48 . . . 74-84 . . . 84-1 To this supposed difference has commonly been ascribed the greater brittleness of bones in aged people; but recent analyses tend to show that bone is at all periods of individual life chemically the same, and if so, the inference growing out of the error of former analyses is false. The development of bone takes place in a manner somewhat differ- ent from that of most other tissues, since we have, in addition to the germinal matter and formed material, a deposit of earthy matter in the latter. The formation of the animal matter is a vital phenomenon, the deposit of earthy matter a purely physical one. The "cell" or "elementary part" of bone consists of a soft central 48 OSTEOLOGY. mass of germinal matter, surrounded by a thin layer of soft formed material with which it is continuous, and which " passes uninterrupt- edly into the hard calcified formed material." This hard formed ma- terial is everywhere perforated by little channels called canaliculi, along which the nutrient material is conveyed to the germinal matter. These canaliculi are formed in a manner corresponding to the deposi- tion of the mineral matter, that is, from without inward, commencing at a point most distant from the germinal matter. In the dried bone these canals are seen to communicate with little vacant spaces called lacuna?, occupied in the fresh state with germinal matter, seeming to associate them one with another. In this manner, each lacuna com- municates freely with adjacent lacunae. The only part of the bone, in Dr. Beale's opinion, which can be said to be living, is the "nucleus" or "bone cell" in the space or lacuna, constituting perhaps one-twelfth part of the bone; all the rest being as dead in the living body as when removed from it. " It (the germi- nal matter) alone can grow and give rise to the formation of matrix. Bone cannot produce bone, but the germinal matter of bone may become converted into new bone tissue." Virchow is of the opinion that the matrix is true intercellular substance into which proceed stellate pro- cesses from the cells occupying the lacunae, thus giving rise to the canaliculi; an opinion directly opposite to that of Dr. Beale, that the canaliculi begin in the matrix (which is not formed independently of the cell, but consists simply of the formed material, or cell wall, in which mineral matter has been deposited,) and extend to the germinal matter occupying the lacunal space. This germinal matter is always present in the lacuna ; on it depends the circulation of the calcareous matter held in solution by the blood ; without it bone tissue cannot be formed, and on its presence the life of the bone depends. The canaliculi, then, are the " altered spaces or ducts which are left between the calcare- ous globules originally deposited, and through them pass fluids to and from the germinal matter." (Beale On the Structure and Growth of Tissues, 128.) Originally triangular in form, they finally become so altered by the filling up of the angles as to exhibit a circular appearance on transverse section. The osseous tissue with its canaliculi and germinal matter always bears a fixed and definite relation to the vessels It may exist as solid cylindrical processes covered with a vascular mem- brane, or as thin laminae also covered with a vascular membrane or as concentric laminae arranged round a central opening, a " Haversian canal. Each Haversian canal has a diameter of about one-five- hundredth of an inch; though they are of very different sizes, varying from one-fifteen-hundredth to one-two-hundredth of an inch in diameter The elementary parts of bone are so arranged as to form either the BONES OF THE HEAD AND FACE. 49 loose and spongy or cancellated bone tissue, or the more solid and com- pact or laminated tissue, as in the shaft of a long bone; and between these, in health, a transitional stage may always be observed, while in disease the compact tissue may undergo such modification as to resem- ble the cancellated. There are also " large spaces like cancelli" in the compact tissue called the " Haversian spaces," which are merely the canals enlarged by erosion taking place from within outward. The canals and spaces which finally form the fat cells may also undergo conversion into bone tissue, and are originally derived from the same elementary parts as those from which bone is formed. CHAPTER IV. BONES OF THE HEAD AND FACE. THE osseous structures in which the student of dentistry is especially interested, and to which we would direct attention, are: 1. The superior maxillary or upper jaw bones. 2. The inferior maxillary or lower jaw bones. 3. The palate bone. THE SUPERIOR MAXILLARY BONES. The Superior Maxillary Bones, two in number, are in pairs and united on the median line of the face. They occupy the anterior upper part of the face, are of very irregular form, and consist of a body and processes. They are the largest bones of the face except the inferior maxilla, and enter into the formation of three cavities, the orbit, the mouth, and the nares; they also enter into the formation of the zygomatic and spheno-maxillary fossae, and the spheno-maxillary and pterygo-maxillary fissures. The body is the central part of the bone, and has four surfaces; namely, the external or facial, the posterior or pterygoid, the superior or orbital, and the internal or palatine. The External Surface is irregularly convex, and has a depression about its centre just above the canine and first bicuspid teeth, called the canine fossa: immediately above which is the infra-orbital foramen for transmitting an artery and nerve of same name; its upper and inner edge forms part of the lower margin of the orbit, to which is attached the levator labii superioris proprius muscle. 4 NATIONAL LIBRARY OF MEDICINE 50 BONES OF THE HEAD AND FACE. The Posterior Surface has a bulging, called tuberosity, which is con- nected with the palate bones, and bounds the antrum behind; it is perforated by three or four small holes, — the posterior dental canals which transmit nerves and bloodvessels to the molar teeth. This OUTER Fig. 1. SURFACE TENDO ocuir—j-Q INCISIVE FOSSA POSTERIOR DENTM CANALS MAXIUARV TUBEROSITY C*»W£. BICUSPIDS. surface presents also on its nasal face a groove which becomes by articulation with the palate bone the posterior palatine canal. The Internal Surface extends from the alveolar processes in front to the horizontal plate of the palate bones behind, called the palatine processes, which are rough below, forming the roof of the mouth, and smooth above, making the floor of the. nostrils. They are united along the median line, at the anterior part of which is the foramen incisivum, having two openings in the nares above, while there is but one in the mouth below. The body of the superior maxilla is occupied by a large and very important cavity called the Antrum Highmorianum, or Maxillary Sinus. This cavity is somewhat triangular in shape, with its base generally looking to the nose, and its apex to the malar pro- cess. Its upper wall is formed by the floor of the orbit, its lower by the aiveoli of the molar teeth, which sometimes perforate this cavity. The canine fossa bounds it in front, while the tuberosity closes it BONES OF THE HEAD AND FACE. 51 behind. But the shape of this cavity is exceedingly variable. In ex- amining a collection of nearly one hundred maxillae in the Museum of the Baltimore Dental College, no two sinuses were found to be shaped alike; and this difference is as marked between the right and the left in the same, as in different subjects. The floor of some is nearly flat, but in the majority of cases it is very uneven; sometimes crossed by a single septum, varying from one-eighth to half an inch in height; at other times there are found three or four septa, dividing the lower part of the cavity into as many separate compartments, with the bottom or floor of no two on a level with each other. Some are per- forated by the roots of one or more teeth; at other times the roots of several teeth extend considerably above the level of the floor of the antrum, covered by a lamina of bone scarcely thicker than bank-note paper. In other cases, the floor of the antrum is half an inch above the extremities of the roots of the teeth. This cavity also varies as much in size as it does in shape. Fig. 2. The opening of the antrum is, on its nasal portion or base, into the middle meatus of the nose ; in the skeleton it is large, while in the natural state it is much contracted by the ethmoid bone above, the inferior turbinated bone below, the palate bone behind, and by the 52 BONES OF THE HEAD AND FACE. mucous membrane which passes through the opening and lines the in- terior of the antrum. A deep groove lies in front of the opening in the antrum, which is converted into a canal for the nasal duct by the lachrymal and inferior turbinated bones. The Malar Process is a rough, triangular process, marking the boundary between the external and internal surfaces. It presents on its upper margin a roughened surface for articulation with the malar bone. The Nasal Process forms the lateral boundary of the nose. It is a thick, triangular prominence articulating at its upper extremity by a serrated edge with the frontal bone, and by an uneven surface with the ethmoid bone; a little lower on its internal surface it offers a transverse ridge, the superior turbinated crest, for articulation with the middle turbinated bone ; below this is the inferior turbinated crest to which is attached the inferior turbinated bone; and lying between these crests is a smooth concave space, forming part of the middle meatus, while beneath the inferior crest is a like space which forms part of the inferior meatus. By its anterior border it is articulated with the nasal bone, and by its posterior with the lachrymal bone, forming with it the canal for the nasal duct, whilst at the junc- tion of the anterior lip of the nasal groove with the orbital surface is placed the lachrymal tubercle, serving as a guide to the duct in all operations for fistula lachrymalis. The Alveolar Process is formed on the lower edge of the external surface; it is broader behind than in front, and is perforated with ex- cavations corresponding in number with the teeth, those depressions which receive teeth of more than one fang are sub-divided by bony septa into compartments of a sufficient number to receive these fangs. The bottom of each of these cavities is perforated by a small foramen, for the passage of nerves and bloodvessels which supply the teeth. The alveolar border externally presents a fluted ap- pearance ; the projections cor- respond with the alveolar cavi- ties, and the depressions with the septa which divide them from one another. The Palate Process forms the roof of the mouth and part of the floor of the nose; it is thick and strong, and presents in front the orifice of the anterior palatine canal through which passes the anterior palatine BONES OF THE HEAD AND FACE. 53 vessels, whilst the inferior naso-palatine nerves pass along the inter- maxillary suture. The inferior surface at the back part has a deep groove, sometimes a canal, for the passage of the posterior palatine vessels, and a nerve of large size; it is also perforated with numerous foramina for the passage of nutrient vessels. The outer border is closely attached to the rest of the bone. The inner border, thicker in front than behind, presents a ridge which, together with a similar ridge on the opposite bone, forms a groove in which the vomer is received. The anterior margin is prolonged into a sharp process, the nasal spine. By its posterior border it articulates with the horizontal plate of the palate bone. The structure of the upper jaw, with its alveolar and numerous other processes, is thick and cellular; the cancellated structure being invested with a thin layer of compact bone. It is articulated with two bones of the cranium, the frontal and ethmoid, and seven of the face, namely: the nasal, malar, lachrymal, palate, inferior turbinated, vomer, and to its fellow, by sutures ; also to the teeth by the articulation termed gomphosis. Its development'commences at so early a period of intra-uterine life, and ossification proceeds so rapidly, that the number of ossific centres is uncertain : some give a centre for the body and each process, others think that most probably there are but four centres in all. It may be seen as early as the thirty-fifth or fortieth day after conception ; and although at birth it has acquired but little height, it has increased con- siderably in breadth. But, at this period, the alveolar border, which constitutes the largest portion of the bone, is almost in contact with the orbit. The antrum is still scarcely perceptible, but as the vertical dimensions of the bone are increased, it is gradually developed. With the loss of the teeth, the alveolar border nearly disappears, so that the vault of the palate loses its arched form, and sometimes becomes almost flat. The Upper or Orbital Surface is triangular in shape, with its base in front forming the anterior, lower, and internal edge of the orbit; while its apex extends back to the bottom, forming the floor of the orbit and roof of the antrum ; its internal edge is united to the lachrymal, ethmoid, and palate bones; its external edge assists in forming the spheno-maxillary fissure, and along its central surface is seen a canal running from behind, forward and inward,— the infra-orbital canal. This canal divides into two: the smaller is the anterior dental, which descends to the anterior alveoli along the front wall of the antrum; the other is the proper continuation of the canal, and ends at the infra- orbital foramen. 54 BONES OF THE HEAD AND FAC THE INFERIOR MAXILLARY BONE. Fig. 4. $V0' CO/Vo. The Inferior Maxillary Bone (Fig. 4) is the largest bone of the face; and though single in the adult, it consists of two symmetrical pieces in the foetus. It occupies the lower part of the face, has a parabolic form, and ex- tends backward to the base of the skull. It is divided into a body and extremities. The body is the middle and horizontal portion ; this is divided along its centre by a ridge called the symphysis, which is the place of separa- tion in the infant state; the middle portion projects at its inferior part into an eminence called the mental process or chin; on each side of which is a depression for the muscles of the lower lip; and externally to these depressions are two foramina, called anterior mental, for trans- mitting an artery and nerve of the same name. The horizontal portions extend backward and outward; and on the outward surface have an oblique line for the attachment of muscles. On the inner surface of the middle part behind the chin, along the line of the symphysis, there is a chain of eminences called genial tuber- cles; to the superior of which the fraenum linguae is attached, to the middle the genio-hyo-glossi, and to the inferior the genio-hyoid mus- cles ; on each side of these eminences are depressions for the sublingual glands; and beyond these depressions there runs an oblique ridge upward and outward, to the anterior part of which is attached the mylo-hyoid muscle, and to the posterior part, the superior constrictor BONES OF THE HEAD AND FACE. 55 of the pharynx; this latter muscle is consequently involved more or less in the extraction of the last molar tooth. Below this line there is a groove for the mylo-hyoid nerve, and a depression, the submaxillary • fossa, for the reception of the submaxillary gland. Fig. 5. The alveolar border, in the foetus, constitutes nearly the whole body of the bone. After the loss of the teeth, this part of the inferior max- illary is gradually wasted. The alveolar border, in the lower jaw, describes a rather smaller arch than it does in the upper, and both its anterior walls are thinner than the posterior. Passing over the infe- rior border, near the junction of the body with the ramus, is a groove for the facial artery. The extremities of the body have two large processes rising up at an obtuse angle, named the rami of the lower jaw. These processes are flat and broad on their surfaces; the outer one is covered by the mas- seter muscle; the inner one has a deep groove which leads to a large hole, the posterior dental or maxillary foramen, for transmitting the inferior dental nerves and vessels to the dental canal running along the roots of the teeth. This foramen is protected by a spine to which the spheno-maxillary ligament is attached. The ramus has a projection at its lower part, which is the angle of the lower jaw; its upper ridge is curved, having a process at each end — the anterior one is the coronoid process; this is triangular, and 56 BONES OF THE HEAD AND FACE. has the temporal muscle inserted into it; the posterior is the condyloid, and articulates with the temporal bone. This process has a neck which receives the insertion of the external pterygoid muscle. The Coronoid Process is thin, flat, and triangular. To its external sur- face is attached the temporal and masseter muscles. On its internal sur- face is a longitudinal ridge extending to the posterior part of the alveolar process, and to which is attached the temporal muscle above and the buccinator muscle below. In front of this ridge is a deep groove, to which the temporal and buccinator muscles are in part attached. The Condyloid Process consists of two portions — a condyle and a neck. The condyle is of an oval form, convex both laterally and from before backward. The neck of the condyle, flattened from before backward, convex on its posterior surface, presents anteriorly a de- pression, the pterygoid fossa, for the attachment of the external ptery- goid muscle. Between these two processes is the sigmoid notch, a semilunar depression over which passes the masseteric artery and nerve. The structure of the inferior maxilla is compact externally, cellular within, and is traversed in the greater part of its extent by the inferior dental canal. The lower jaw is developed from two centres of ossification, which meet at the symphysis. It articulates on each side by one of its con- dyles with the glenoid cavity of the temporal bone, situated at the base of the zygomatic process. This cavity is divided into two portions — an anterior and a posterior. The former constitutes the articular por- tion, the latter lodges a process of the parotid gland. The two are separated by the fissure of Glasserius, which transmits the chorda tympani nerve, the laxator tympani muscle, and the anterior tympanic artery. It also gives lodgment to the long process, processus gracilis, of the malleus. Between this cavity and the condyle there is interposed an inter- articular cartilage, so moulded as to fit the two articular surfaces. The circumference of this being free, except where it adheres to the external lateral ligament, affords attachment to a few fibres of the ex- ternal pterygoid muscle, and facilitates the movements of the joint. The union of this articulation is maintained by the external lateral, the spheno-maxillary, and the stylo-maxillary ligaments. THE PALATE BONES. The Palate Bones, two in number, are situated at the back part of the superior maxillary bone, between its tuberosities and the pterygoid processes of the sphenoid bone. BONES OF THE HEAD AND FACE. 57 The palate bone is divided into three plates: the horizontal or pala- tine, the vertical or nasal, and the orbital. The palate plate is broad and on the same line with the palate pro- cesses of the superior maxillary bone; its upper surface is smooth and forms the posterior floor of the nostrils, the lower surface is rough and forms the posterior part of the roof of the mouth; its anterior edge is connected with the palate process of the upper jaw, and its posterior is thin and crescentric, to which is attached the velum-pendulum palati or soft palate; at the posterior point of the suture, uniting the two palate bones, there projects backward a process called the posterior nasal spine, which gives origin to the azygos-uvulae muscle. The ver- tical plate ascends, helps to bound the nasal cavity, diminishes the opening into the antrum by projecting forward, and by its external posterior part, in conjunction with the pterygoid processes of the sphenoid bone, forms the posterior palatine canal; the lower orifice of which is seen on the margin of the palate plate, and is called the pos- terior palatine foramen, transmitting the palatine nerve and artery to the soft palate; behind this foramen is often seen a smaller one, pass- ing through the base of the pterygoid process of this bone, and sending a filament of the same nerve to the palate. Fig. 6. jf*P Off*,.. *«i MAXILLARY SURFACE SUPERIOR MEATUS SPHCIIO PALATINE FORAMEN HORIZONTAL PLATE The upper end of the vertical or nasal plate has two processes — the one is seen at the back of the orbit, called the orbital process; the other is posterior, and fits against the under surface of the body of the sphenoid bone. Between these two processes is a foramen, the spheno- 1 58 MUSCLES. palatine, which transmits to the nose a nerve and artery of the same name. The palate bone articulates with six others, namely: the superior maxillary, inferior turbinated, vomer, sphenoid, ethmoid, and opposite palate. Fig. 7. SPHENO.PALA TINE FOR A. SPHENOIDAL PROCESS rici/LAfi pour. exr.stmr. NON ARTICULAR POfir. The structure of this bone is very thin, and consists almost entirely of compact tissue. Its development, it is said, takes place by a single point of ossi- fication at the union of the vertical, horizontal, and pyra- midal portions. The bones of the head are twenty-two in number, of which eight compose the cranium and fourteen the face. Those of the cranium are one frontal, two parietal, two temporal, one occipital, one sphenoid, and one ethmoid. Those of the face are six pairs and two single bones; the pairs are the two malar, two superior maxillary, two lach- rymal, two nasal, two palatine, and two inferior turbinated. The vomer and inferior maxillary are the two single bones. POST. NASAL SP/t/E CHAPTER V. MUSCLES. lyTUSCLES are the fleshy parts of the body. They are the active 1T.L organs of locomotion, and are composed of fibres bound together in bundles, or fasciculi, by delicate areolar tissue. The muscular fibres of which each muscle is compounded are called ultimate fibres. Of these anatomists recognize two kinds__volun- tary or animal fibres, and involuntary or organic fibres. The former are generally under the influence of the will, are of uniform size, and present transverse markings. They compose the muscles of the trunk and limbs as well as those of the heart, urethra, internal ear, and, in part, those of the oesophagus,—though these latter are not subject to the will. MUSCLES. 59 The involuntary fibres are not under volitional control, are not striped, are of smaller size and homogeneous structure. They are found in the digestive canal, uterus, and bladder. The voluntary muscles terminate in fibrous tissue, which is sometimes gathered to- gether in bundles to form tendon, or is spread out in a membranous form, and is then called aponeurosis. By one or the other of these terminal forms almost all muscles are attached to those parts which it is their office to move. The involuntary muscles are generally found interlacing freely around a cavity, which, by their contraction, they constrict, expelling its con- tents. Each muscle is closely though loosely invested by a sheath of cellular tissue, which also sends prolongations into the body of the muscle, investing each fibre and binding them together. Muscles are variously named, according to their form, long, broad, short, etc. These names sufficiently explain themselves. Other names are given them, depending on the arrangement of their fibres, their situation, number of divisions, office, etc.; for fuller explanation, students are referred to more exclusively anatomical works. The Fascia, which everywhere invests the more delicate organs, is of two kinds—superficial or fibro-areolar, and deep or aponeurotic. The superficial facia lies just beneath the skin, and covers nearly the entire surface of the body. It serves to connect the skin with the deep facia, and furnishes a nidus for nerves and bloodvessels passing to the skin. The deep facia is composed of fibres arranged in a reticulated man- ner, forming a dense, inelastic membrane, which invests each muscle in a separate sheath. Sheaths are also formed from it for the vessels and nerves; and it serves also as points of attachment for the muscles. Each striped muscular fibre is composed of two parts — a proper substance called the sarcous element, in which the contractile property resides, and a sheath or sarcolemma, a transparent, structureless mem- brane, in which is contained the contractile substance. These element- ary fibres are connected by areolar tissue, with which a little fat is often associated. Lying between these fibres are bloodvessels, nerves, and lymphatics. The sarcous element is a soft, granular material, on the varying rela- tions of which granules to each other depend the alterations in ap- pearance of the striae. If they approach each other more closely in the direction of the length of the fibre than in its width, it will appear fibrillated; if the reverse, it will present the appearance of discs. Muscles, like all other tissues, are developed from germinal matter which has undergone special metamorphosis, under the impulse of the parent cell, to construct this tissue. " Germinal matter" and "formed 60 MUSCLES. material"constitute the "elementary part,"—according to Mr. Beale, — or the muscular cell of other writers from which the muscular fibre is formed. In the formed material, which is the constructed muscle, resides the power of contraction. The germinal matter or constructive part does not possess this property. Following the arrangement of Mr. Gray, we shall divide the muscles, which it is our purpose to describe, into certain groups, as follows: 1. Nasal Group. 5- Pterygo-Maxillary Group Pyramidalis Nasi. Pterygoideus Externus. Levator Labii Superioris Alseque Nasi. Pterygoideus Internus. Levator Proprius Alae Nasi Posterior. fi Lingual Group. Levator Proprius Alae Nasi Anterior. _ XT . Genio-hyo-glossus. Compressor Nans. J ° Compressor Narium Minor. v0"g Depressor Alae Nasi. Lingualis. Stylo-glossus. 2. Superior Maxillary Group. Palato-glossus. Levator Labii Superioris Proprius. ,. _ . 7. Pharyngeal Group. Levator Anguu Oris. Zygomatics Major. Constrictor Inferior. Zygomaticus Minor. Constrictor Medius. Constrictor Superior. 3. Inferior Maxillary Group. Stylo-pharyngeus. Levator Labii Inferioris. Palato-pharyugeus. Depressor Labii Inferioris. Depressor Anguli Oris. 8. Palatal Group. Levator Palati. 4. Temporo-Maxillary Group. Tensor Palati. Masseter. Azygos Uvulae. Temporal. Palato-glossus. Palato-pharyngeus. 1. Nasal Group. Pyramidalis Nasi. Levator Labii Superioris Alaeque Nasi. Levator Proprius Alae Nasi Posterior. Levator Proprius Alae Nasi Anterior. Compressor Naris. Compressor Narium Minor. Depressor Alae Nasi. The Pyramidalis Nasi is a triangular, muscular slip extended from the occipito frontalis. It lies along the side of the nose, and blends by a tendinous expansion with the compressor naris. The Levator Labii Superioris Alceque Nasi is also a triangular muscle, arising from the nasal process of the superior maxilla, its upper part. Passing down behind the muscle just described, it divides into two muscular slips, one of which is inserted into the cartilage of MUSCLES. 61 the ala of the nose, the other is continued to the angle of the mouth, where it blends with the orbicularis oris and levator labii proprius. Beneath this muscle is a small muscular slip extending from the origin of the compressor naris to the nasal process, about an inch above it. It is called the " Musculus Anomalus," or the " Rhomboideus." The Levator Proprius Aloe Nasi Posterior, or Dilator Naris Poste- rior, extends from the nasal notch to the margin of the nostril. The Levator Proprius Aloe Naris Anterior, or the Dilator Naris Anterior, is situated a little in front of the last described muscle, and arises from the cartilage of the wing of the nose, and is inserted into the integument near its margin. The Compressor Naris, triangular in form, arises from the superior maxilla, a little above and external to the incisive fossa, and is attached to the fibro-cartilage of the nose joining at the median line with its fellow of the opposite side. The Compressor Narium Minor extends from the alar cartilage to the integument of the end of the nose. The Depressor Aloz Nasi arises from the incisive fossa of the supe- rior maxilla, and dividing into two sets of fibres, ascending and descend- ing, is inserted into the septum and posterior portion of nasal cartilage, and by some fibres of the latter into the back part of the orbicularis oris. The facial nerve supplies all the muscles of this group. Their respective actions are sufficiently explained by their names, except the pyramidalis, which draws down the inner angle of the eye- brow, and perhaps aids in dilating the nostril; and the compressores nasi, whose action is directly opposite to that implied by their names. The contraction of the levator labii superioris alaeque nasi gives to the face the expression of contempt. 2. Superior Maxillary Group. Levator Labii Superioris Proprius. Levator Anguli Oris. Zygomaticus Major. Zygomaticus Minor. The Levator Labii Superioris Proprius arises from the lower margin of the orbit, some of its fibres from the superior maxillary, others from the malar bone; they pass down to be inserted in the fleshy part of the upper lip. The Levator Anguli Oris arises from the canine fossa just below the infra-orbital foramen, and descends to the angle of the mouth, where it blends with the orbicularis oris, the zygomatici, and the depressor anguli oris muscles. The Zygomaticus Major is a delicate fasciculus, arising from the 62 MUSCLES. malar bone and finding attachment to the orbicularis and depressor an- guli oris at the angle of the mouth. The Zygomaticus Minor arises from the malar bone just behind the maxillary suture, and passes downward and inward to be inserted in the outer margin of the levator labii superioris, with which it is con- tinuous. These muscles are also supplied by the facial nerve. The action of the levator muscles is described in their names. The zygomatici draw the lip upward and outward, as in laughing. 3. Inferior Maxillary Group. Levator Labii Inferioris, (Levator Menti.) Depressor Labii Inferioris, (Quadratus Menti.) Depressor Anguli Oris, (Triangularis Menti.) The Levator Labii Inferioris arises from the incisive fossa just exter- nal to the symphysis of the chin: it is a small conoidal fasciculus, and is inserted into the integument of the chin. The Depressor Labii Inferioris is a quadrilateral muscle arising from the oblique line of the inferior maxilla, between the incisive fossa and mental foramen, and is attached to the integument of the lower lip, blending with the orbicularis oris and with its fellow of the opposite side. The Depressor Anguli Oris, situated externally to the last mentioned muscle, also arises from the external oblique line of the lower jaw, and is attached at the angle of the mouth to the orbicularis, levator anguli, and zygomaticus major muscles. The facial nerve supplies this group. Their action is indicated by their names. 4. Temporo-Maxillary Group. Temporal. Masseter. The Temporal Muscle (Fig. 8) is seen on the side of the head. It has its origin from the semi-circular ridge commencing at the external angu- lar process of the os-frontis, and extending along this and the parietal bone; also from the surfaces below this ridge formed by the frontal and squamous portion of the temporal and sphenoid bones; likewise from the under surface of the temporal aponeurosis, and from a fascia covering this muscle; and its fibres are inserted, after they have con- verged and passed under the zygoma, into the coronoid process of the lower jaw, surrounding it on every side by a dense strong tendon. The Masseter Muscle (Fig. 9) is seen at the side and back part of the face in front of the meatus externus, and lies directly under the MUSCLES. 63 skin. It arises by two portions: the one anterior and tendinous, from the superior maxilla where it joins the malar bone; the other portion, mostly fleshy, from the inferior edge of the malar bone and the zygo- matic arch as far back as the glenoid cavity, and is inserted, tendinous and fleshy, into the external side of the ramus of the jaw and its angle as far up as the coronoid process. The inferior maxillary nerve supplies both these muscles. The office of the temporal muscle is to bring the two jaws together, as in the cutting and rending of the food. The use of the masseter muscle, when both portions act together, is to close the jaws; if the anterior acts alone, the jaw is brought for- ward, if the posterior, it is drawn backward. Fig. 8. The use of the pterygoid muscle is to aid the temporal and masseter muscles in the trituration of the food. The external pterygoids carry the lower jaw directly forward when acting together, to one or the other side when acting separately The internal pterygoid aids the masseter and temporal in bringing the lower jaw firmly up against the superior maxilla, and also assists in carrying the lower jaw forward. The inferior maxillary nerve supplies these muscles, which form the pterygo-maxillary group, and which come next in order of description. 64 MUSCLES, 5. Pterygo-Maxillary Group. Pterygoideus Externus. Pterygoideus Internus. Pterygoideus Externus (Fig. 10) arises from the outer surface of the external plate of the pterygoid process of the sphenoid bone, from the tuberosity of the superior maxilla, and from the ridge on the sphenoid Fig. 9. bone separating the zygomatic from the pterygoid fossa, and is inserted into the inner side of the neck of the lower jaw, and capsular ligament of the articulation. Pterygoideus Internus arises, tendinous and fleshy, from the inner surface of the pterygoid plate, fills the greater part of the pterygoid MUSCLES. 65 fossa, and is inserted, tendinous and fleshy, into the inner face of the angle of the inferior maxilla and the rough surface above the angle. The external one is triangular, having its base at the pterygoid pro- cess and running outward and backward to the neck of the condyle. The internal is strong and thick, placed on the inside of the ramus of the jaw, and running downward and backward to the angle. Fig. 10. 6. Lingual Group. Genio-hyo-glossus. Hyo-glossus. Lingualis. Stylo-glossus. Palato-glossus. The Genio-hyo-glossus is attached, as its name implies, to the chin, hyoid bone, and tongue. It is a triangular, fan-like muscle, arising by its apex from the superior genial tubercle, and has its inferior fibres running parallel with the genio-hyoid to be inserted into the hyoid bone, while its middle and anterior fibres are inserted into the under surface of the tongue its whole length. The Hyo-glossus, a thin, broad, quadrilateral muscle, has its origin from the body, cornu, and appendix, of the os-hyoides, and is inserted into the side of the tongue, forming the greater part of its bulk. The Lingualis has its origin on the under surface of the tongue, ex- tending from its base and the hyoid bone to the apex, and so inter- 5 66 MUSCLES. mingling with the other muscles as to be considered rather a part of them than a distinct muscle. The Stylo-glossus arises from the point of the styloid process and stylo-maxillary ligament. It is inserted into the side of the tongue near its root, its fibres running to the tip. Fig. 11. The Palato-glossus is more directly associated with the soft palate, and will consequently be described with the palatal group. 7. Pharyngeal Group. Constrictor Inferior. Constrictor Medius. Constrictor Superior. Stylo-pharyngeus. Palato-pharyngeus. The Inferior Constrictor of the pharynx (Fig. 12) arises from the side of the thyroid cartilage and its inferior cornu, and from the side of the cricoid cartilage, and is inserted with its fellow into the middle MUSCLES. 67 line on the back of the pharynx. This is the largest of the constrictor muscles, and overlaps the middle constrictor. The Middle Constrictor of the pharynx (Fig. 12) arises from the appendix and both cornua of the os-hyoides, and from the thyro-hyoid ligament; its fibres ascend, run transversely and descend, giving a tri- angular appearance; the upper ones overlap the superior constrictor, while the lower are beneath the inferior; the whole pass back to be inserted into the middle ten- dinous line of the pharynx. The Superior Constrictor (Fig. 12) arises from the cuneiform process of the occipital bone, from the lower part of the internal pterygoid plate of the sphenoid bone, from the pterygo- maxillary ligament, and from the posterior third of the mylo- hyoid ridge of the lower jaw, near the root of the last molar tooth. It is inserted with its fellow into the middle tendinous line at the back of the pharynx. The Stylo-pharyngeus arises from the root of the styloid pro- cess, and is inserted into the side of the pharynx and corner of the os-hyoides and thyroid car- tilage. It is a long and narrow muscle, and passes to the pha- rynx between the upper and middle constrictors. The Palato-pharyngeus, which forms the posterior pillar of the soft palate, is a long, fleshy muscle, wider at either extremity than in the middle, and arises from the soft palate by a divided fasciculus, between which points of attachment lies the levator-palati. It passes behind the tonsil, downward and outward, to be inserted into the posterior part of the thyroid cartilage, together with the stylo-pharyngeus. The muscles of this group are supplied with nerves from the pharyn- geal plexus and glossopharyngeal nerve; an additional branch from the external laryngeal nerve being sent to the inferior constrictor; the palato-pharyngeus receives a branch from Meckle's ganglion. These muscles are exercised in the act of deglutition, and also exert an influence in modulating the voice. 68 MUSCLES. 8. Palatal Group. The Levator Palati. The Tensor, or Circumflexus Palati. Constrictor Isthmi-faucium, or Palato-glossus. Palato pharyngeus. Azygos-uvulae. The Levator Palati (Fig. 13) arises from the point of the petrous portion of the temporal bone and adjoining portion of the Eustachian tube, descends and is inserted into the soft palate. The Tensor, or Circumflexus Palati, arises from the base of the pterygoid process of the sphenoid bone and from the Eustachian tube; it Fig. 13. descends in contact with the internal pterygoid muscle to the hamulus, round which it winds, and is inserted into the soft palate, where it ex- pands and joins its fellow. The Constrictor Isthmi-faucium, or Palato-glossus, occupies the ante- MUSCLES. 69 rior lateral half arches of the palate; it arises from the side of the tongue near its root, and is inserted into the velum near the uvula. The Palato-pharyngeus has already been described with the muscles of the pharyngeal group. The Azygos-uvuloz arises from the posterior spine of the palate bones at the termination of the palate suture, runs along the central line of the soft palate, and ends in the point of the uvula. It raises and shortens the uvula. It is thus seen that the various muscles of the soft palate are all concerned, more or less, in conducting the food into the pharyngeal cavity. The elevators raise the palate, and at the same time protect the posterior nares from regurgitation of the food; while the tensor puts it on the stretch, and after it has passed the velum, the con- strictor isthmi-faucium and palato-pharyngeus draw the palate down, and thus close the opening into the mouth; after which the food, as already mentioned, is grasped by the constrictor muscles of the pharynx, and conveyed into the oesophagus. The Soft Palate is a movable curtain, composed of mucous mem- brane, inclosing several muscles. It is situated at the back part of the mouth between this cavity and the pharynx, is connected above to the posterior edge of the hard palate, and laterally to the side of the tongue and pharynx. By this arrangement, the soft palate has the appearance of a lunated or arched veil between the cavity of the mouth and the pharynx. In the centre of this arch an oblong body is suspended, called the uvula, which divides the soft palate into lateral half arches, that pass on either side from the uvula to the root of the tongue. There is also seen passing from the uvula on each side to the pharynx, two other arches, which, from being behind the first, are called the posterior arches or pillars. Between the anterior and posterior pillars, on either side, is a trian- gular interval containing the tonsil glands. The Fauces are the straits or passage leading from the mouth to the pharynx; and the space included between the soft palate above, the half arches or tonsils on either side, and the root of the tongue below, is called the isthmus of the fauces. The Tonsils are two bodies, each about the size of an almond, seen at the root of the tongue on its sides, occupying the cavity between the anterior and posterior half arches. They consist of a group of compound follicular glands, forming somewhat oval bodies, whose en- largement constitutes an obstacle to deglutition, and by their locality near the mouths of the Eustachian tubes, frequently cause obstruction and deafness. 70 BLOODVESSELS OF THE MOUT CHAPTER VI. BLOODVESSELS OF THE MOUTH. THE arteries that supply the mouth come from the external carotid. This is a division of the common carotid which arises on the right side from the arteria innominata, and on the left from the arch of the Fig. 14. INCISTUS aorta; after passing up the neck on either side along the course of the sterno-cleido-mastoid muscles, it divides on a level with the top of the thyroid cartilage into its two great branches—the external and in- ternal carotid arteries. The Internal Carotid Artery has a tortuous course; is first to the outside and behind the external carotid; then ascends in front of the vertebral column by the side of the pharynx and behind the digastric and styloid muscles to the carotid foramen in the petrous portion of the temporal bone; thence it traverses the canal in this bone and BLOODVESSELS OF THE MOUTH. 71 enters the brain, supplying it with most of its vessels, not giving any to the mouth. The External Carotid extends from the top of the larynx to the neck of the condyle of the lower jaw; at first anterior and on the inside of the internal carotid, it soon gets to the outside, then passes under the digastric and stylo-hyoid muscles and lingual nerve, becomes imbedded in the parotid gland, and terminates between the neck of the inferior maxilla and the auditory meatus in the temporal and in- ternal maxillary arteries. The branches of the external carotid with which we have to do are the Lingual. Facial. Ascending Pharyngeal. Temporal. Internal Maxillary. The Lingual Artery arises from the external carotid, between the superior thyroid and facial; passing obliquely up to the great corner of the hyoid bone, it runs parallel with, and ascending perpendicularly to the base of the tongue, continues its course to the tip of that organ, under the name of the ranine artery. This part of the artery lies just beneath the mucous membrane, and is in danger of being wounded in division of the fraenum in children. This accident may be avoided by using blunt-pointed scissors, and directing the points downward and backward. The hypo-glossal nerve accompanies this artery. The branches of the lingual artery with which we are concerned are the Dorsalis Linguae. Sublingual. Ranine. The Dorsalis Linguce arises from the lingual artery, beneath the hyo- glossus muscle, and is distributed to the tonsil, epiglottis, soft palate, and mucous membrane of the tongue. The Sublingual arises from the lingual at the point of bifurcation, near the anterior margin of the hyo-glossus muscle, and passes forward to be distributed to the sublingual gland, to the mucous membrane of the mouth and gums, and to the neighboring muscles. The Ranine may be considered the continuation of the lingual. It passes along the inferior surface of the tongue just beneath its mucous membrane. At the tip of the tongue it anastomoses with its fellow of the opposite side. It is accompanied by the gustatory nerve. 72 BLOODVESSELS OF THE MOUTH. The Facial Artery is the third branch of the external carotid. It ascends to the submaxillary gland, behind which it passes on the body of the lower jaw — thence it goes in front of the masseter muscle to the angles of the mouth, and finally terminates at the side of the nose by anastomosing with the ophthalmic arteries. In its course it gives off the submental, inferior labial, superior and inferior coronary arteries, which mainly supply the elevators, depres- sors, and circular muscles of the mouth. The branches of the facial artery are divided into two sets: Cervical Branches. Facial Branches. Inferior or Ascending Palatine. Muscular. Tonsillitic. Inferior Labial. Submaxillary. Inferior Coronary. Submental. Superior Coronary. Lateralis Nasi. Angular. The Inferior Palatine passes up between the stylo-glossus and stylo- pharyngeus muscles, which it supplies, to give branches to the tonsil, Eustachian tube, soft palate, and palatine glands, anastomosing with the tonsillitic artery, and with a branch of the internal maxillary. The Tonsillitic Artery is distributed to the tonsil and root of the tongue. The Submaxillary supplies the submaxillary gland, together with the neighboring lymphatic glands, muscles, and integument. The Submental is the largest of the cervical branches of the facial artery ; it is given off from it just as it emerges from the submaxillary gland, and passing along the lower border of the inferior maxilla is dis- tributed to the muscles attached to the jaw, and terminates in a super- ficial and deep branch; the former of which is distributed to the depressor labii inferioris and integument, anastomosing with the in- ferior labial; the latter is also distributed to the lip, and anastomoses with the inferior labial and mental arteries. The Facial branches are distributed to the muscles of the face. The muscular to the pterygoid, masseter and buccinator muscles. The superior coronary to the upper lip, giving branches to the septum and ala nasi. The inferior coronary passes to the lower lip, and anasto- moses with its fellow of the opposite side. The lateralis nasi sup- plies the wing and back of the nose. The angular is the terminal branch of the facial. It supplies the cheek, lachrymal sac, and orbic- ularis palpebrarum muscle, and terminates by anastomosing with the ophthalmic by its nasal branch. The Ascending Pharyngeal, the smallest of the external carotid branches, is given off from the posterior part of the external carotid, BLOODVESSELS OF THE MOUTH. 73 passes up beneath its other branches and the stylo-pharyngeus muscle to the base of the skull ; it has three sets of branches — the external, meningeal, and pharyngeal. To the latter only do I wish to direct attention. The Pharyngeal branches are three or four in number, two of which are distributed to the middle and inferior constrictors and to the stylo- pharyngeus, and their mucous membrane. The largest branch sup- plies the tonsil, Eustachian tube, and soft palate, substituting the palatine branch of the facial when it is absent or of small size. The Temporal Artery gives off a transverse facial branch just before it emerges from the parotid gland which is distributed to that gland, the masseter muscle and the integument, terminating by anastomosis with the facial and infra-orbital arteries. The Internal Maxillary Artery commences in the substance of the parotid gland; then goes horizontally behind the neck of the condyle of the lower jaw to the pterygoid muscles, between which it passes, and then proceeds forward to the tuberosity of the superior maxillary bone; from thence it takes a vertical direction upward between the temporal and external pterygoid muscles to the zygomatic fossa, where it again becomes horizontal, and, finally, ends in the spheno-maxillary fossa by dividing into several branches. The branches of this artery which we shall describe are the— Inferior Dental. Alveolar. Infra-orbital. Descending Palatine. The Inferior Dental Artery enters the inferior dental foramen of the lower jaw, passes along the dental canal beneath the roots of the teeth; sending up, in its course, a twig through the aperture of each to the pulps of the teeth, and, finally, escapes at the mental foramen on the chin ; a branch of it, however, continues forward to supply the incisors. After emerging from the mental foramen, it supplies the muscles and integument of the chin and anastomoses with the inferior labial, sub- mental, and inferior coronary arteries. Before entering the dental foramen a large branch, the mylo-hyoid, which lies in a groove of the same name on the inner surface of the maxillary bone and is lost on the under surface of the mylo-hyoid muscle, is given off. The Alveolar is given off from the internal maxillary by a trunk common to it and the infra-orbital, just before it enters the spheno- maxillary fossa. At the tuberosity of the superior maxillary bone it divides into numerous branches„gSome of which passing into the alveo- lar foramina supply the bicuspid and molar teeth ; others pierce the bone to supply the antrum, whilst some are distributed to the gums. The Infra-orbital Artery enters the infra-orbital canal, traverses its 74 BLOODVESSELS OF THE MOUTH. whole extent, and comes out at the foramen of the same name upon the face; just before it emerges it sends through the anterior dental canal a twig for the incisors and cuspids, having previously given branches to the inferior rectus and inferior oblique muscles, and to the lachrymal gland, also other branches to the lining membrane of the antrum. After escaping from the orbit, it supplies the lachrymal sac and neighboring tissues and anastomoses with the facial, nasal branch of the ophthalmic, and with the transverse facial and buccal branches. The Descending Palatine passes along the posterior palatine canal, accompanied by palatine branches of Meckel's ganglion, emerging thence it runs along a groove on the inner border of the alveoli, and is distributed to the mucous membrane of the hard palate, to the gums and the palatine glands. In the posterior palatine canal it gives off branches, which pass along the accessory palatine canal to be dis- • tributed to the soft palate. In front it terminates in a small branch which enters the anterior palatine canal, through which it passes to reach the septum naris, where it unites with a branch of the spheno- palatine. The Veins correspond so nearly, both in name and course, with the arteries, that a description of them would be only a repetition of what has been said ; suffice it, therefore, to observe, that there are two com- panion veins with every considerable artery, and that the venous branches are mostly collected at the angle of the jaw into a common trunk called the external jugular vein, which passes down the neck in the course of the fibres of the platysma muscle, and terminates in the subclavian vein at the posterior edge of the sterno-mastoid muscle. The office of the veins is to return the blood to the heart. THE NERVES OF THE MOUTH. 75 CHAPTER VII. THE NERVES OF THE MOUTH. THE nerves supplying the mouth belong to the fifth pair, and the portio dura of the seventh or facial nerve. Fig. 15. The Fifth (Trigemini) is the largest of the cranial nerves, and gives sensibility to all the organs concerned in the primary stages of diges- tion. This nerve will also be found to be a compound nerve, having motor filaments as well as sensitive, and thereby giving motion as well as sensation. It is also a nerve of special sense. It is first seen at the side of the pons Varolii near its junction with the crura-cerebelli, but its origin is much deeper and further back. It 76 THE NERVES OF THE MOUTH. arises by two unequal roots, one of which may be traced through the pons Varolii into the lateral tract behind the olivary body ; the smaller, or motor root, is lost in the medulla oblongata. From its origins this nerve has been called a cranial-spinal nerve. These two fasciculi, the one anterior and the other posterior, consti- tute the fifth nerve, which consists of eighty or one hundred filaments that pass forward and outward, in a canal formed of dura mater, to a depression on the anterior surface of the petrous bone. At this point it spreads into a ganglion, called the Casserian gang- lion, on the under surface of wdiich is seen the anterior root; but it has no intimate connection with the ganglion, and can be traced on, as will be presently shown, to the inferior maxillary nerve. The Casserian ganglion receives filaments from the carotid plexus of the sympathetic, and gives off several minute branches to the dura mater and tentorium cerebelli. Three large branches are given off from its anterior border, the ophthalmic and superior, and inferior maxillary. The ophthalmic and superior maxillary are exclusively nerves of sensation, their fibres being derived entirely from the poste- rior or sensory root, whilst the inferior maxillary receives fibres from both roots, and is consequently more variously endowed. The Ophthalmic Nerve is a short trunk, that enters the orbit through the foramen lacerum superius. It supplies the eye-ball, the mucous membrane of the eye and nose, and the lachrymal gland, also the muscles and integument of the eye-brow and forehead. It is a sensi- tive nerve; is the first given off from the Casserian ganglion, and is the smallest of the three branches. It receives a few filaments from the cavernous plexus of the sympathetic, and divides into three prin- cipal branches. 1. The Frontal, 2. The Lachrymal, and 3. The Nasal. The Frontal, which is the largest branch of the ophthalmic, passes along the roof of the orbit to the supra-orbital foramen, through which it passes, and is then called the supra-orbital nerve, and is spent on the muscles and integuments of the forehead. It gives off several branches in its course. The Lachrymal, the smallest branch of the ophthalmic, generally arises by two branches, one from the fourth and the other from the ophthalmic. It enters the orbit through the sphenoidal fissure, receives a communicating branch from the superior maxillary, and is finally distributed to the lachrymal gland, taking the outward direction, and sending branches in its course to the upper eyelid, conjunctiva, and other parts, receiving on the eyelid branches from the facial. I THE NERVES OF THE MOUTH. 77 The Nasal takes its direction along the inner side of the orbit to the anterior ethmoidal foramen, through which it passes into the cranium, on the upper surface of the cribriform plate of the ethmoidal bone; descends by the side of the crista-galli through a slit-like opening into the nose, and there terminates by filaments which are spent upon the septum, mucous membrane, anterior nares, &c. It sends off several branches in its course; one in particular to the lenticular ganglion at the bottom of the eye, others to the caruncula lachrymalis, lachrymal sac, conjunctiva, &c.; but as these do not belong to the mouth and dental apparatus, we will pass to the second great division of the fifth. the superior maxillary nerve. This nerve proceeds from the middle of the Casserian ganglion, passes through the foramen rotundum of the sphenoid bone, into the pterygo-maxillary fossa; here it enters the canal of the floor of the orbit — the infra-orbital canal, — traverses its whole extent, and emerges on the face at the infra-orbital foramen, where it terminates in numerous filaments in the muscles and integuments of the upper lip, cheek, lower eyelid, and side of the nose. The superior maxillary nerve supplies the upper jaw, and gives off many important branches, which are as follows: In the pterygo-maxillary fossa two branches descend to a small red- dish body called the ganglion of Meckel, or the spheno-palatine gan- glion, situated on the outer side of the nasal or vertical plate of the palate bone. From this ganglion proceed three sets of branches: 1. Inferior, Descending, or Palatine Nerves. 2. Nasal, or Spheno-palatine. 3. Posterior, Pterygoid, or Vidian. The Palatine Nerves descend through the posterior palatine canal, come out at the posterior palatine foramen along with an artery of the same name, and supply with filaments the soft palate, uvula, tonsils, the roof of the mouth, and the inner alveoli and gums. The Nasal Nerves enter the nose through the spheno-palatine fora- men, and divide into several filaments which enter the mucous mem- brane covering the upper and lower turbinated bones and vomer; one long branch can be traced along the septum nasi as far as the foramen incisivum, where it meets the anterior palatine branches in a ganglion called the naso-palatine. The Vidian, or Pterygoid, passes backward from the ganglion of Meckel through the pterygoid canal at the root of the pterygoid pro- cess ; then enters the cranium through the foramen lacerum anterius, and divides into two branches, one of which enters the carotid canal 78 THE NERVES OF THE MOUTH. an _d unites with the sympathetic branches of the superior cervical gan- glion, thus connecting this ganglion with the ganglion of Meckel. The other, the proper vidian nerve, enters the vidian foramen or hiatus Fallopii in the petrous bone, joins the portio dura nerve, accom- panies this as far as the back part of the tympanum; then leaves it, enters the cavity of the tympanum, and receives there the name of Chorda Tympani. It leaves this cavity by the glenoid fissure, then joins the gustatory nerve, continues with it to the submaxillary gland, where it leaves it and is lost in the submaxillary ganglion, situated at the posterior part of the submaxillary gland. The exceedingly intricate course of the vidian nerve is interesting from the number of communications which it establishes between dif- ferent and distant parts: for it unites the ganglion of Meckel with the superior cervical ganglion of the sympathetic, and both with the sub- maxillary ganglion; it also connects the superior and inferior maxil- lary nerves to one another and to the portio dura. The Superior Maxillary Nerve gives off next in the spheno-maxil- lary fossa: 1. The Orbital. 2. The Posterior Dental. 3. The Anterior Dental. The Orbital enters the orbit through the spheno-maxillary fissure, and then sends off a malar and temporal branch, which pass out through the malar bone; the first supplying the cheek, the latter ac- companying the temporal artery to the integuments of the side of the head, receiving filaments from the facial and auriculo-temporal branch of the inferior maxillary. The Posterior Dental Nerves, two in number, descend on the tuber- osity of the superior maxillary bone, and enter the posterior dental canals to supply the bicuspid and molar teeth; one branch penetrates the antrum and courses along the outer wall, anastomosing with the anterior dental nerves, while another runs along the alveolar border supplying the gums. The Anterior Dental is given off from the superior maxillary just before it escapes from the infra-orbital foramen. It anastomoses with the posterior dental, and sends filaments to the incisor, canine, and first bicuspid teeth; others are sent to the mucous membrane of the inferior meatus. ^ This nerve now emerges, as before mentioned, at the infra-orbital foramen, between the levator labii superioris alaeque nasi and levator anguli muscles, dividing here into many branches; some of which ascend to the nose and eyelids, others pass downward and outward to THE NERVES OF THE MOUTH. 79 the lip and cheek, anastomosing with the nasal branch of the ophthal- mic, and the facial branches of the portio dura. INFERIOR MAXILLARY NERVE. This nerve forms the third great division of the fifth. It is the largest branch, and passes from the ganglion of Casser through the foramen ovale of the sphenoid bone to the zygomatic fossa. This nerve, as stated, is attached to the anterior or motor root, and they come together on the outside of the foramen ovale: then in the zygomatic fossa, the inferior maxillary nerve divides into two branches: 1. Anterior. 2. Posterior. The Anterior is the motor branch, and gives off the following fila- ments to the several muscles : 1. Masseteric, crossing the sigmoid notch to the masseter muscle. 2. Temporal, anterior and posterior deep, to the temporal mus- cle and fascia. 3. Buccal, to the buccinator, external pterygoid, and temporal muscles. 4. Pterygoid, to the pterygoid muscles. The Internal division of the inferior maxillary nerve consists of three branches, all of which are sensitive; they are: 1. The Anterior Auricular. 2. The Gustatory. '3. The Inferior Dental. The Anterior Auricular passes behind the neck of the lower jaw and m front of the meatus of the ear, and ascends through the parotid gland, over the zygoma along with the temporal artery, and divides into anterior and posterior branches. In its course it unites with the facial nerve, and supplies the parotid gland, the articulation of the lower jaw, the meatus, and cartilages of the ear and side of the head. The Gustatory Nerve, the nerve of the special sense of taste, imme- diately after its origin, sends a branch to the inferior dental; it then descends between the pterygoid muscles, where the chorda tympani joins it; it now passes along the ramus of the lower jaw, covered by the internal pterygoid muscle, then above the submaxillary glands, and forward above the mylo-hyoid and between it and the hyo-glossus muscles, accompanied by the duct of Wharton ; and finally ascends above the sublingual gland to the lateral, inferior, and anterior parts of the tongue. 80 THE NERVES OF THE MOUTH. In its course, Mr. Harrison enumerates the following branches as given off by this nerve: " First, one or two small filaments to the internal pterygoid muscle. Second, several to the tonsils, to the muscles of the palate, to the upper part of the pharynx, and to the mucous membrane of the gums. Third, the chorda tympani, and some accompanying filaments to form a plexus, which supplies the submaxillary gland. Fourth, a few branches which descend along the hyo-glossus muscle to communicate with the ninth or lingual nerve. Fifth, a fasciculus of nerves to the sublingual gland and to the surrounding mucous membrane. Lastly, at the tongue it divides into several branches, some pass deep into the tissue of this organ; others, firm and soft, rise toward its surface, and are lost in the mucous membrane and in a small conical papilla near its tip." The Inferior Dental Nerve passes between the pterygoid muscles, then along the ramus of the lower jaw under the pterygoideus internus to the inferior dental foramen, which it enters along with an artery and vein; it now traverses the inferior dental canal, sending twigs into all the roots of the molars and bicuspids. Opposite the mental foramen it divides into two branches, the smaller is continued forward in the substance of the jaw to supply the roots of the cuspids and incisors; while the larger comes out at the mental foramen, is distributed to the muscles and integuments of the lower lip, and, finally, communicates with the facial nerve. The inferior dental, just as it enters the posterior dental foramen, gives off the mylo-hyoid nerve ; this passes forward in a groove of the lower jaw, and supplies the mylo-hyoid, and digastric muscles, and oc- casionally the submaxillary gland. THE FACIAL NERVE. The Portico dura of the seventh or facial nerve is the last nerve to be noticed as particularly belonging to the mouth. The Facial Nerve arises from the medulla oblongata between the olivary and restiform bodies, close behind the lower margin of the pons Varolii; it then passes forward and outward with the portio mollis to the foramen auditorium internum, which it enters and passes on to the base of this opening; here these two nerves separate, the portio mollis going to the labyrinth of the ear; while the facial enters the aqueduct of Fallopius, in which it is joined by the vidian. Within the aqueductus Fallopii it gives off two branches — the tympanic and chorda tympani. The former supplies the stapedius muscle. The latter THE NERVES OF THE MOUTH. 81 Fig. 16. passes along a distinct canal and enters the cavity of the tympanum near the attachment of the membrana tympani, where it is covered by mucous membrane. It escapes from this cavity by the inner side of the Glasserian fissure ; after receiving a communicating branch from the gustatory nerve it passes to the submaxillary gland, then joining the submaxillary ganglion it is lost in the lingual muscle. The facial then goes in a curved direction outward and backward behind the tympanum, where it parts with the vidian, and proceeds on to the stylo-mastoid foramen, from which it emerges. At this point it sends off three small branches : 6 82 THE NERVES OF THE MOUTH. 1. The Posterior Auricular, 2. The Stylo-hyoid, and 3. The Digastric. The Posterior Auricidar ascends behind the ear, crosses the mastoid process, where it receives branches from the pneumogastric, and the auricularis magnus ; it then divides into two branches, one of which passes to the retrahens aurem, the other to the occipito-frontalis muscle. The Stylo-hyoid is distributed to the stylo-hyoid muscle. It com- municates with filaments of the sympathetic sent to the carotid artery. The Digastric is distributed to the posterior belly of the digastric muscle, receiving a communicating branch from the glosso-pharyn- geal. The facial nerve, while deeply imbedded in the substance of the parotid gland, divides into two sets of branches, of which one is superior and the other inferior; these two, by frequent unions, form the pes anserinus or parotidean plexus, and send branches to the whole of the side of the face. The upper division, called the temporo-facial, ascends in front of the ear upon the zygoma, accompanies the temporal artery and its branches, supplying the side of the head, ear, and forehead, and anas- tomosing with the occipital and supra-orbital nerves ; a set of branches pass transversely to the cheek, furnishing the lower eyelid, lips, and side of the nose, and uniting with the infra-orbital nerve. The inferior or cervico-facial division descends, supplying the lower jaw and upper part of the neck, giving off the following branches: 1. Buccal. 2. Inferior Maxillary, and 3. Cervical. The Buccal, or superior branches, supply the muscles of the cheek, nose, and upper lip. The Inferior Maxillary nerves are distributed in the muscles of the chin and lower lip, and by means of anastomotic branches communi- cate with the inferior dental nerve. The Cervical branches form a close connection with the superior cer- vical nerves, and supply the platysma myoid muscle and the levator labii superioris. The facial is the motor nerve of the face, ?rd by its means the pas- sions or emotions find their expression in the peculiar action of the muscles to which it is distributed. In consequence of the numerous communications which this nerve SALIVARY GLANDS. 83 has with other nerves, the name of Sympatheticus Minor has been given to it by some anatomists. Mr. Gray furnishes the following concise statement of these com- munications. In the internal auditory meatus, With the auditory nerve. With Meckel's ganglion by the large In the aquaeductus Fallopii, petrosal nerve. With the. otic ganglion by the smaller petrosal nerve. With the sympathetic on the middle meningeal by the external petrosal nerve. r With the pneumogastric. " " glosso-pharyngeal. " " carotid plexus. " " auricularis magnus. " " auriculotemporal. On the face.........With the three divisions of the fifth. At its exit from the stylo-mastoid foramen, CHAPTER VIII. SALIVARY GLANDS. THE Salivary Glands are six in number, three on each side of the face, named the Parotid, Submaxillary, and Sublingual. These'glands are the prime organs in furnishing the salivary fluids to the mouth during the process of mastication. The Parotid Gland (Fig. 17), so called from its situation near the ear, is the largest of the salivary glands. Its form is very irregu- lar; it fills the space lying between the ramus of the inferior maxdla and mastoid process of the temporal bone, as far back as, and even behind, the styloid process of the same bone. Its extent of surface is from the zvgoma above to the angle of the lower jaw below, and from the mastoid process and meatus behind to the masseter muscle in front, overlapping its posterior portion. _ This gland is one of the conglomerate order, and consists of numer- 84 SALIVARY GLANDS. ous small lobes connected together by cellular tissue; each of which may be considered a small gland in miniature, as each is supplied with an artery, vein, and excretory duct. The gland thus formed presents on its external surface a pale, flat, and somewhat convex appearance. It is covered by a dense, strong fascia extending from the neck, and attached to the meatus externus of the ear, which sends countless pro- cesses into every part of the gland, separating its lobules and con- ducting the vessels through its substance. The use of this gland is to secrete or separate from the blood the greater part of the saliva furnished to the mouth. As the parotid is, however, on the outside, and at some little distance from the mouth, it is furnished with a duct to convey its fluid into this cavity; this duct is called the duct of Steno, or the parotid duct. It is formed of the excretory ducts of all the granules composing this gland, which, suc- cessively uniting together, at last form one common duct. The duct of Steno commences at the anterior part of the gland and SALIVARY GLANDS. 85 passes over the masseter muscle, on a line drawn from the lobe of the ear to the middle part of the upper lip ; then passes through a quan- tity of soft adipose matter, and finally enters the mouth by passing through the buccinator muscle and mucous membrane opposite the second molar of the upper jaw. The arteries supplying this gland are from the external carotid or some of its branches. The nerves are derived from the carotid plexus of the sympathetic, and from the facial, temporal, and great auricular. The parotid secretion is a clear, watery, alkaline liquid, which is poured out abundantly during mastication, but in very small quantity when the mouth is at rest. Its secretion may also be excited by men- tal emotion, as, when observing a savory article of food, or by artificial stimuli, as of glass beads or other irritants in the mouth. The following analysis is taken from Dalton's Physiology : COMPOSITION OF HUMAN PAROTID SALIVA. Water, ........ .983-308 Organic matter precipitable by alcohol, .... 7-352 Substance destructible by heat, but not precipitated by alcoholar acids, 4-810 Sulpho-cyanide of sodium, ...... 0-330 Phosphate of lime, ....... 0-240 Chloride of potassium. ...... 0-900 Chloride of sodium and carbonate of soda, .... 3 060 Total, . . . . . . . . 1000-000 It will be seen that the quantity of organic matter is comparatively large. Observation has shown that this secretion is unilateral, the saliva flowing only from that side on which mastication is then being con- ducted, and that the quantity is directly related to the physical char- acter of the food, and not to its chemical constitution, being more or less abundant, according to the dryness of the food. The Submaxillary is the next in size of the salivary glands. It is situated under and along the inferior edge of the body of the lower jaw, and is separated from the parotid simply by a process of fascia. It is of oval form, pale color, and, like the parotid, consists in its structure of small lobules, held together by cellular tissue; each having a small excretory duct, which, successively uniting with one another, finally form one common duct. This, the duct of Wharton, passes above the mylo-hyoid muscle, and running forward and inward, enters the mouth below the tip of the tongue at a papilla seen on either side of the fraenum linguae. 86 SALIVARY GLANDS. The use of this gland is the same as the parotid, to secrete a fluid constituent of the saliva, and its duct is the route by which it is con- ducted into the mouth. Its arteries are derived from the facial and lingual. The veins correspond. Its nerves are received from the sub- maxillary ganglion, the inferior dental and sympathetic nerves. The Sublingual Glands are the last in order of the salivary glands, and the smallest in size. They are situated beneath the anterior and lateral parts of the tongue, are covered by the mucous membrane, and rest upon the mylo-hyoid muscle. They, like the two glands just described, consist of a lobular struc- ture with excretory ducts; which, however, do not unite into one com- mon duct, but enter the cavity of the mouth by many ducts, whose openings are through the mucous membrane between the tongue and the inferior cuspid and bicuspid teeth. Their office is the same as the parotid and submaxillary. Their arteries are derived from the sublingual and submental. Their nerves from the gustatory. The Mucous Glands. Besides the glands furnishing the saliva, there is another series of much smaller'size, called the mucous glands. They are simply the little crypts, follicles, or depressions everywhere found in the mucous membrane of the mouth, and named, according to their situation, the glandulae labiales, glandulae buccales, etc. The lips, cheeks, and palate are also furnished with glands, about the size of a small pea, which present the true salivary structure. The use of these glands is to furnish the mucous of the mouth, which they pour into this cavity by single orifices, opening everywhere on its surface. The Saliva consists of the commingled secretion of all these glands — salivary glands are found in all vertebrate animals except fishes. It is a glairy, slightly opalescent, alkaline fluid, consisting of organic and mineral substances held in solution with water. Its composition, accord- ing to Bidder and Schmidt, is as follows: COMPOSITION OF SALIVA. Water,........... 995-16 Organic Matter, ......... 1-34 Sulpho-cyanide of Potassium, ...... 0-06 Phosphate of Soda, Lime, and Magnesia, ..... -98 Chlorides of Sodium and Potassium, ..... -84 Mixture of Epithelium,........1-62 1000-00 SALIVARY GLANDS. 87 Two kinds of organic matter exist in the saliva,—-the first, which is found in the submaxillary and sublingual secretions, is called ptyaline; to it the saliva owes its viscidity. Alcohol coagulates it, but heat does not, differing, in this respect, from the organic matter derived from parotid gland, which is coagulated by heat and is not viscid. The sulpho-cyanogen, the only mineral ingredient that is peculiar to saliva, is detected by a solution of the chloride of iron, with which it strikes a red color characteristic of it. When saliva has stood for some time it deposits a whitish flocculent sediment, which is found under the microscope to consist of epithelium scales, and other small nucleated cells, granular matter, and oil globules. Although saliva possesses the power to change' the starchy matter of the food into sugar, yet in view of the facts that this change is inter- rupted by the gastric juice with which it is so soon to come in contact, and that the quantity secreted is directly related to the physical char- acteristics of the food, and not to its chemical constitution, not being more abundant during the mastication of starchy food, except it be dry, than of any other aliment, and, furthermore, since the conversion of starch into sugar is otherwise provided for, it may be considered as an established fact that its only purpose is to aid mechanically in mas- tication and deglutition by moistening and lubricating the food. The quantity of saliva secreted daily has been variously estimated by different observers. Mitscherlich thought it about fourteen ounces daily, and Todd and Bowman consider his estimate reliable. Bidder and Schmidt estimated it at about three and a half pounds avoirdupois, and Mr. Dalton at " rather less than three pounds avoirdupois," which is probably very nearly correct. THE TONGUE. The Tongue is a very complicated organ; it consists of a great va- riety of parts, and performs a great variety of functions; it is one of the organs of deglutition ; a glandular organ, to secrete; a sentient organ, to feel and taste; and likewise an intellectual organ, to assist in producing speech. The tongue is divided into apex, body, and root; the apex is the an- terior free and sharp portion ; the root, which is thin, is attached to the os hyoides and is posterior; while the body, which occupies the centre, is thick and broad ; it is confined in its situation by the origins of its component muscles, and by reflections of the mucous membrane. The mucous membrane of the tongue covers its free surface every- where; it is thinnest on its under surface, where it may be traced along the ducts of the submaxillary and sublingual glands. Passing 88 SALIVARY GLANDS. over the dorsum, it assumes a papillary character, and becomes much thickened. The papillae of the tongue are the papillae circumvallatae, papillae fungiformes, and papillae filiformes. The papillae circumvallatae (maximae) are situated on each side of the back part of the tongue, meeting at the foramen coecum so as to form a triangular figure. They number from eight to fifteen. Each papilla is arranged in the form of an inverted cone, with its apex received into a depression of mucous membrane, and its base ex- posed on the free surface, and upon it may be seen numerous smaller papillae. The papillae fungiformes are scattered irregularly over the surface of the tongue, but are most numerous at its sides and apex. They also are studded on their free surface with smaller papillae. The papillae filiformes are found on the anterior two-thirds of the tongue, and are very minute. They are somewhat conical or filiform in shape, are covered with an unusually dense epithelium which gives them a whitish appearance, and are filled with secondary papillae. Small hairs are often found in them. Structure of the Papillae. — They consist of capillary loops, through which nerves are abundantly distributed, covered by a homogeneous tissue, upon which is superposed a thick layer of squamous epithelium. The nerves are large and numerous in the papillae circumvallatae; in the papillae fungiformes and papillae filiformes they are smaller. In the mucous membrane are also found follicles or glands. The former are very numerous, especially so between the circumvallate papillae and the epiglottis, but are found scattered over the entire sur- face of the tongue. The latter, called mucous or lingual glands, are most abundant on the posterior third of the tongue, but are found also on its tip, sides, and in the neighborhood of the circumvallate papillae. The ducts open on the free surface of the mucous membrane. THE MUCOUS MEMBRANE LINING THE MOUTH. The whole interior cavity of the mouth, palate, pharynx, and lips, is covered by mucous membrane, forming folds or duplicatures at dif- ferent points, called fraena or bridles. Beginning at the margin of the lower lip, this membrane can be traced lining its posterior surface, and from thence reflected on the anterior face of the lower jaw, where it forms a fold opposite the symphysis of the chin —the fraenum of the lower lip; it is now traced to the alveolar ridge, covering it in front, and passing over its posterior surface, where it enters the mouth. Here it is reflected from the posterior symphysis of the lower jaw to the SALIVARY GLANDS. 89 under surface of the tongue, where it forms a fold or bridle called the frcenum lingua;. It now spreads over the tongue, covering its dorsum and sides to the root, from whence it is reflected to the epiglottis, form- ing another fold; from this point it can be followed, entering the glottis and lining the larynx, trachea, etc. In the same way, commencing at the upper lip, it is reflected to the upper jaw, and at the upper central incisors forming a fold, the frcenum of the upper lip; from this it passes over the alveolar ridge to the roof of the mouth, which it completely covers, and extends as far back as the posterior edge of the palate bones; from this it is reflected down- ward over the soft palate; or, more strictly speaking, the soft palate is formed by the duplicature of this membrane at this point, between the folds of which are placed the muscles of the palate already described. From the palate it is traced upward and continuous with the mem- brane lining the nares, and downward with the same, lining the pharynx, oesophagus, stomach, and intestinal canal. The mucous membrane, after entering the nostrils and lining the roof, floor, septum nasi, and turbinated bones, enters the maxillary sinus between the middle and lower spongy bones, and lines the whole of this great and important cavity of the superior maxilla. Many mucous glands or follicles, already enumerated, are scattered over the whole of this membrane, and furnish the mouth with its mucus. THE GUMS. The gums are composed of dense, elastic, fibrous tissue adhering to the periosteum of the alveolar processes. They are remarkable for their insensibility and hardness in the healthy state, but exhibit great tenderness upon the slightest injury, when diseased. In the infant state of the gums, the central line of each dental arch presents a white, firm, cartilaginous ridge, which gradually becomes thinner as the teeth advance; and in old age, after the teeth drop out, the gums again resume somewhat their former infantile condition, showing "second childhood." The gums, being endowed with a high degree of vascularity, indi- cate very correctly, as the author has stated in another part of the work, the state of the constitutional health. THE ALVEOLO-DENTAL PERIOSTEUM. This membrane may be properly noticed here, as it is considered by some as continuous with the gums. It lines the alveolar cavities, or sockets of the teeth, covers the roots of each, is attached to the gums at the necks, and to the bloodvessels and nerves where they enter the roots of the teeth at their apices; and, further, Mr. Thomas Bell be- 90 SALIVARY GLANDS. lieves it passes into the cavities of the teeth, forming their lining mem- brane, and is continuous with, or the same as that of the pulp. The original sac has been stated in another place to consist of two membranes, an outer and an inner; these are attached to the gums, and when the teeth come through these membranes and the gums, the sac remaining behind, especially its outer coat, is supposed by some to constitute the alveolo-dental periosteum, and to be continuous with the gums; while, on the other hand, Mr. Bell believes both membranes of the sac to be wholly absorbed, and that the true alveolo-dental peri- osteum is the same as the periosteum covering the upper and lower maxillary bones, continuing into the alveolar cavities, lining their parietes, and thence being reflected on the roots of the teeth. It matters little whether this membrane be a continuation of the gums, the remains of the pulp-sac, or the extension of the periosteum of the maxillary bones into the alveolar cavities, since the great practical truth still remains, that there is a membrane lining the alveolar cavities and investing the roots of the teeth, and that this membrane is fibrous, and constitutes the bond of union between the alveolar cavities and the roots of the teeth. The Dental Ligament, so recently discovered by a dentist, formerly of Virginia, but now of Philadelphia, is attached to the necks of the teeth, and whose opinion, I am sorry to add, has the support of Dr. Goddard, bears no more resemblance to true ligament than the nails do to bone. It consists of the fibres that unite the alveolar to the dental periosteum, which, according to the last-named gentleman, "are very numerous just at the margin of the alveolus;" but it can lay no reasonable claim to the title of ligament. ANATOMICAL RELATIONS OF THE MOUTH. * The mouth has many interesting anatomical relations with the rest of the body, a few of which it may be well to mention. By means of its lining mucous membrane it is connected through continuity of structure with the pharynx, oesophagus, stomach, and the whole of the intestinal canal, etc. Disease still further establishes this structural relation. Inflamma- tion, ulceration, or any other pathological change in the stomach or intestines is felt and reported on the tongue, gums, and other parts of the mouth, showing the sympathy and the close relationship of these several parts. The mouth is also connected by the same mucous membrane with the organs of respiration by being continued down into the larynx, trachea, and bronchi. SALIVARY GLANDS. 91 Wide-spread sympathies are established between the mouth and other parts by means of the numerous nerves which animate the parts constituting its boundaries and lying in its cavity, as the sympathetic, the seventh, the glosso-pharyngeal, the par vagum, the hypo-glossal, and the upper cervical. Simple irritation from teething has thrown children into convul- sions, and in adults toothache often creates extreme irritability of the whole nervous system. But it is not necessary to dwell here on the sympathies of the mouth in disease with other parts of the body, as the author will have occasion to do this in other parts of the work. It will be well, however, to mention in this place, that there is a general anatomical relation of the mouth with the rest of the body, by means of the bloodvessels and areolar tissue. PHYSIOLOGICAL RELATIONS. It has been shown that the mouth consists of a great variety of parts, and, also, that it has an equally great diversity of functions. The functions of the mouth have been stated to be those of pre- hension, mastication, insalivation, and deglutition. These functions, it has been seen, are all closely related to one another, and mutually dependent; and how beautiful is the harmony of action as well as its regular and orderly succession! We see, in the first place, the prehensile instruments laying hold of and intro- ducing the food into the mouth; then the organs of mastication, the teeth and upper and lower jaw bones, put into operation by the tem- poral, masseter and pterygoid muscles, grind it down into minute por- tions ; these, at the same time, are formed into a bolus by being mixed with the salivary fluids, furnished by the parotid, submaxillary and sublingual glands; then the mass is taken by the organs of deglu- tition, namely, the tongue, palate and pharynx, and passed into the oesophagus, to be thence conducted into the stomach, thus demon- strating the harmony existing among the several functions belonging to the mouth. But the functional relation of the mouth is no less extensive than its structural relation; the one is commensurate with the other; and as the structure of the mouth has been shown to be continuous with that of other parts of the body, so we find that the functions of the mouth exert an influence upon, and are themselves influenced by many great and leading functions of the body. The connection between mastication and insalivation, for example, with stomachal digestion, or chymification, is especially obvious. Again, the mouth is intimately related with the intellectual func- tions* as,'for instance, that of speech. Who does not know that when 92 THE TEETH. any of the teeth are wanting, the palate cleft, or there is a hare-lip, how much the speech is impaired ? And so with all the other func- tions of the body; the relation between them and the mouth, and the mutual dependence of each on the other, is equally demonstrable. CHAPTER IX. THE TEETH. fPHE teeth are the prime organs of mastication, are the hardest por- _L tions of the body, and are implanted in the alveolar cavities of both the upper and lower jaw. A tooth is composed of four distinct structures: — 1. The pulp, oc- Fxg. 18. Fig. 18.—a, The coronal surface divested of enam- el; b, The dentine ; c, The pulp cavity; d, The ce- mentum, or crusta petro- sa; e, The enamel. cupying the chamber in the crown and the canal extending through the root; 2. The dentine, which constitutes the principal part of the organ ; 3. The enamel, which forms the covering and protection of the crown; 4. The cementum, or crusta petrosa, which covers the root. (See Fig. 18.) The teeth of first dentition, termed the milk, temporary, or deciduous teeth, are de- signed merely to supply the wants of child- hood, and are replaced with a larger, stronger, and more numerous set. These are termed the permanent or adult teeth, and are in- tended to continue through life. The anatomical divisions of a tooth are: 1. The crown or exposed part situated above the gum; 2. The root occupying the alveolar cavity or socket; 3. The neck which is the constricted portion between the crown and root. THE TEMPORARY TEETH. The temporary teeth are divided into three classes: first, the incisors ; second, the cuspids or canine teeth ; third, the molars, which are succeeded by the bicuspids or premolars. The temporary teeth are twenty in number, ten in each jaw, namely: four incisors, two cuspids, and four molars. FIG. 19. THE TEETH. Fig. 20. 93 Fig. 19—Front or labial view of the temporary teeth of the left side. Fig. 20.—Palatine or lingual view of those on the right side. The pulp-cavity in a temporary tooth is larger in proportion to the size of the organ than in a permanent tooth. Fig. 21. Fig. 22. Fig. 21.—Lateral or side view of temporary teeth. Fig. 22.—Section of ditto, exposing their pulp cavities. THE PERMANENT TEETH. There are thirty-two teeth in the permanent set, sixteen to each jaw — being an increase of twelve over the temporary, designated as follows: incisors, four; cuspids, two; bicuspids or premolars, four; molars, six — in each jaw. The third or last molar is sometimes de- nominated dens sapientioz or wisdom tooth. DESCRIPTION OF TEETH BELONGING TO EACH CLASS. Each tooth, as has already been remarked, has a body or crown, a neck, and a root or fang. In describing these several parts, I shall begin with 94 THE TEETH. The Incisors (four to each jaw, Fig. 23, a a, a a) occupy the anterior central part of each maxillary arch. The body of each is wedge Fig. 23. Fig. 23.—a a, a a, Front view of the incisors ; b b, b b, Palatine or lingual view; c c, c c, Side or lateral view. shape — the anterior or labial surface is convex and smooth; the pos- terior or palatine is concave, and presents a tubercle near the neck; the palatine or labial surfaces come together, and form a cutting edge. In a front view, the edge is generally the widest part; it diminishes toward the neck, and continues narrowing to the extremity of the root. The crown of an incisor has four surfaces: two approximal, one labial, and one palatine or lingual — the term palatine being applied to an upper, and lingual to a lower, incisor. It also has four angles; namely, a right and a left labio-approximal, and a right and left palato- approximal, or lingua-approximal. The two large incisors which are situated one on each side of the median line, are termed the central; the other two, the lateral incisors, or laterals. The crowns of the upper central incisors are about four lines in breadth, and the laterals three. In the lower jaw, the crowns of the central incisors are only about two lines and a half in width, while the laterals are usually a little wider. But the' width of the crowns of all the incisors varies in different individuals. The length of a superior central incisor is usually about one inch, and that of a lateral is half of a line less. In the low7er jaw the central incisors are only about ten lines in length ; the laterals are about one line and a half longer. The length of the crown of an incisor is exceedingly variable. That THE TEETH. 95 of an upper central varies from four and a half to six lines; and there is the same want of uniformity in this respect with the crowns of all the incisors. The roots are all single, of a conical form, flattened laterally, and slightly furrowed longitudinally.. The enamel is thicker before than behind, and thinnest at the sides. The function of this class of teeth, as their name imports, is to cut the food, and for the performance of this office they are admirably fitted by their shape. As age advances, their edges often become blunted; but the rapidity with which they are worn away depends altogether upon the manner in which those of the upper and lower jaw come together. THE CUSPIDATI, OR CUSPIDS. The Cuspidati, Canini, or Cuspids (Fig. 24), are situated next to the incisors, two to each jaw, one on either side. They somewhat resemble the upper central incisors with their angles rounded. Their crowns are conical, very convex externally; and their palatine surface more uneven, and have a larger tubercle than the incisors. Their roots are also larger, and of all the teeth the longest; like the incisors, they are also single, but have a groove extending from the neck to the extremity, showing a step toward the formation of two roots. A cuspid, like an incisor, has four surfaces and four angles, designated by the names already given. The breadth of the crown of an upper cuspid is about four lines, that of a lower is about three and a half; but, as in the case of the in- cisors, the width of the crowns of these teeth is variable. The length of a cuspid is greater than that of any other tooth in the dental series — it being about thirteen lines. The breadth of the neck of one of these teeth is about one-third greater in front than behind, and from before backward it measures about four lines. The upper cuspids are called eye teeth; the lower are termed stomach teeth. These teeth are for tearing the food, and in some of the carnivorous animals, where they are very large, they not only rend but also hold their prey. view of the cuspids; b The incisors and cuspids together are termed j; Palatine and lingual the oral teeth. view; c c, Side view. Fig. 24. 96 THE TEETH. THE BICUSPIDS. Fig. 25. The Bicuspids (Fig. 25), four to each jaw, and two on either side, are next in order to the cuspids. They are so called from their having two distinct prominences or cusps on their grinding surfaces. They are also named the small molars. They are thicker from their buccal to their palatine surface than either of the incisors, and are flatter on their sides. The grinding surface of each is surmounted by two conical tubercles, separated by a groove running in the direction of the alveolar arch; the outer is larger and more prominent than the inner. In the lower jaw these tubercles are smaller than in the upper, and the inner is sometimes wholly wanting. A bicuspid has five sur- faces : namely, two approxi- mal, one anterior and one posterior; one buccal; one palatine or Ungual surface, as the tooth may be in the upper or lower jaw, and one grinding surface. It has also four angles ; one anterior and one posterior palato-approxi- mal, and one anterior and one posterior bucco-approximal angle. The size of these teeth, like that of the incisors and cuspids, is variable. The buccal surface of the crown of a superior bicuspid of ordinary size at its broadest part is about three lines in breadth, while the anterior and posterior approximal surfaces are about four lines. The palatine is not quite as wide as the buccal surface. All the diame- ters of the crown of a lower bicuspid are usually a little less than those of an upper. The entire length of a bicuspid is ordinarily about eleven lines. The roots of the bicuspids are, generally, simple; though the groove is deeper than in the cuspids, and not unfrequently terminates in two roots, which have each an opening for the vessels and nerves to enter. The inner root, however, is always smaller than the outer. Two-fanged bicuspids are more frequently met with in negroes than in whites; and the double fang is common, if not constant, in the aboriginal Austra- lians. Fig. 25.—a a, a a Buccal view of the bicus- pids ; b b, b b Palatine and lingual view ; c c, c c Side view. THE TEETH, 97 THE MOLARS. The Molars (Fig. 26) occupy the posterior part of the alveolar arch, Fig. 26. The upper molars have three c c c> e c c Slde view- roots, sometimes four, and as many as five are occasionally seen ; of these roots two are situated externally, almost parallel with each other, and perpendicular; the third root forms an acute angle, and looks toward the roof of the mouth. The former are called the buccal roots, and the latter the palatine. The roots of the two first superior molars correspond with the floor of the maxillary sinus, and sometimes pro- trude into this cavity, their divergence securing them more firmly in their sockets. The lower molars have but two roots —the one anterior, the other posterior; they are nearly vertical, parallel with each other, and much flattened laterally. 7 98 THE TEETH. The last molar, called the dens sapientice, or wisdom tooth, is both shorter and smaller than the others; the roots of the upper wisdom tooth are, occasionally, united so as to form but one; while the last molar of the lower jaw is generally single and of a conical form. The roots of the molar teeth, both of the upper and lower jaw, after diverging, sometimes approach each other, embracing the intervening bony partition in such a manner as to constitute an obstacle to their extraction. The bucco-palatine diameter of the crown of an upper molar is usually a little less than the antero-posterior. In the lower jaw, the bucco-lingual and antero-posterior diameters are generally about the same. The crown of the first molar is generally larger than the second, and the second larger than the third or wisdom tooth ; and the crown of the last-named tooth is always smaller in the upper than in the lower jaw. The length of a molar tooth varies from eight to twelve and a half or thirteen lines. The molars and bicuspids together constitute what are termed the buccal teeth. The use of the molars, as their name signifies, is to triturate or grind the food during mastication, and for this purpose they are ad- mirably adapted by their mechanical arrangement. ARTICULATION OF THE TEETH. The manner in which the teeth are confined in their sockets, is by a union called gomphosis, from the resemblance of this kind of articula- tion to the way in which a nail is received into a board. Those teeth having but one root, and those with two perpendicular roots, depend greatly for the strength of their articulation on their nice adaptation to their sockets. Those having three or four roots have their firmness much increased by their divergence. But there are other bonds of union; by the periosteum lining the alveolar cavities, and investing the roots of the teeth ; also by the bloodvessels entering the apices of the roots; and finally, by the gums, which will be noticed in another place. DIFFERENCES BETWEEN THE TEMPORARY AND PERMANENT TEETH. The temporary and permanent teeth differ in several respects, and on this point I will give Mr. Bell's observations: " The temporary teeth are, generally speaking, much smaller than THE TEETH. 99 the permanent; of a less firm and solid texture, and their character- istic forms and prominences much less strongly marked. The incisors and cuspids of the lower jaw are of the same general form as in the adult, though much smaller; the edges are more rounded, and they are not much more than half the length of the latter. The molars of the child, on the contrary, are considerably larger than the bicuspids which suc- ceed them, and resemble very nearly the permanent molars. " The roots of the tooth, in the molars of the child, are simi- lar in number to those of the adult molars, but they are flat- ter and thinner in proportion, more hollowed on their inner surfaces, and diverge from the neck at a more abrupt angle, forming a sort of arch." RELATIONS OF THE TEETH OF THE UPPER TO THOSE OF THE LOWER JAW, WHEN THE MOUTH IS CLOSED. The crowns of the teeth of the upper jaw generally describe a rather larger arch than those of the lower. The upper incisors and cuspids usually shut over and in front of the lower; but sometimes they fall plumb upon them, and at other times, though rarely, they come on the inside. The external tubercles or cusps of the superior bicuspids and molars generally strike on the outside of those of the corres- ponding inferior teeth. By this beautiful adaptation of the tubercles of the teeth of one jaw to the depressions of those of the other, every part of the grinding surface of these organs is brought into immediate contact in the act of mastication ; which operation of the teeth, in consequence, is rendered more perfect than it would be if the organs came together in any other manner. The incisors and cuspids of the upper jaw are broader than the corresponding teeth in the lower; in consequence of this difference in the lateral diameter of the teeth of the two jaws, the central incisors of the upper cover the centrals and about half of the laterals in the lower, while the superior laterals cover the remaining half of the inferior and the anterior half of the adjoining cuspids. Continuing this peculiar relationship, the upper cuspids close over the remaining half of the lower and the anterior half of the first inferior bicuspids, 100 THE TEETH. while the first superior bicuspids cover the remaining half of the first inferior and the anterior half of the second. In like manner, the second bicuspids of the upper jaw close over the posterior half of the second and the anterior third of the first molars in the lower. The first superior molars cover the remaining two-thirds of the first in- ferior and the anterior third of the second; while the two-thirds of this last and anterior third of the lower dentes sapiential are covered by the second upper molars. The dentes sapientiae of the superior maxilla, being usually about one-third less in their antero-posterior diameter, cover the remaining two-thirds of the corresponding teeth in the lower jaw. (See Fig. 27.) Thus, from this arrangement of the teeth, it will be seen, that when the mouth is closed, each tooth is opposed to two ; and hence, in biting hard substances, and in mastication, by extending this mutual aid, a power of resistance is given to these organs which they would not otherwise possess. Moreover, as a late English writer, Mr. Tomes, very justly observes, if one, or even two adjoining teeth should be lost, the corresponding teeth in the other jaw would, to some extent, still act against the contiguous organs; and thus, in some degree, counteract a process, first noticed by that eminent dentist, Dr. L. Koecker, which nature sometimes sets up for the expulsion of such teeth as have lost their antagonists. ORIGIN AND FORMATION OF THE TEETH. Of all the operations of the animal economy, none are more curious or interesting than that which is concerned in the production of the teeth. In obedience to certain developmental laws established by an all-wise Creator, it is carried on from about the sixth week of intra- uterine existence, with the nicest and most wonderful regularity until completed, but so secretly conducted, as to prevent the closest scrutiny from detecting with precision the manner in which it is effected; enough, however, is ascertained from its progressive results to excite in the mind of the physiologist the highest admiration. From small papillae, observable at a very early period of foetal life, situated in a groove lined with mucous membrane, and running along the alveolar border of each jaw, the teeth are gradually developed. As they increase in size, the papillae assume the shape of the crowns of the several classes of teeth they are respectively destined to produce. Having arrived at this stage of their formation, they now begin to dentinify, first upon the cutting edges of the incisors, the apices of the cuspids, bicuspids and eminences of the molars; from thence the pro- cess is continued over the whole surface of their crowns, until they become invested with a complete layer of dentine; and so layer after THE TEETH. 101 layer is formed, one within the other, until the process of solidification is completed. But before it has progressed very far, the enamel of the teeth begins to form, and this formative operation is gone through with previously to the completion of the dentinification of the pulps. In the mean time, and in anticipation of the fall of the temporary teeth, a second set is forming, and as the teeth of the one series are re- moved, they are promptly replaced by those of the other. Thus, by a beautiful and most admirable provision of Nature, the first set of teeth, intended to subserve the wants only of childhood, while the jaws are too small for the reception of such as are required for an adult, are re- moved and replaced by a larger, stronger, and more numerous set. The older writers, regarding a knowledge of the earlier stages of the development of the teeth as not of much importance, paid little attention to the subject, and hence this most curious and interesting department of developmental anatomy has remained, until recently, measurably uncultivated. Eustachius, we believe, was the first to notice the position and arrangement of the teeth in the jaws previous to their eruption. But his researches were confined to the examina- tion of the jaws after birth, at which period he speaks of having dis- covered, by dissection, the incisors, cuspids, and three molars on each side, in each jaw, partly in a gelatinous and partly in a solidified condition. He also discovered the incisors and cuspids of the per- manent set behind the first. Eustachius wrote in 1563, and nineteen years later TJrbian Her- man!, a French anatomist and surgeon, although unacquainted with the work of the former, gave a very similar description of the situa- tion of the crowns of the incisors and cuspids of both sets in the jaws of an infant at birth. He represents them as partly bony and partly mucilaginous. He also discovered the bicuspids; but he was unable to find the molars at so early a period as at birth. The researches of Albinus threw no additional light upon the manner of the formation of the teeth, and little was known concerning the earlier stages of the development of these organs until the time of John Hunter, who informs us that in the alveoli of a foetus of three or four months "four or five pulpy substances, not very distinct, are seen." But he says, "about the fifth month the alveolar cavities are more per- fect and the pulps of the teeth more distinct," and that the anterior are more advanced than those further back in the jaws. It is at about this age that he dates the commencement of dentinification on the edge of the temporary incisors. The situation and arrangement of the teeth in the jaws at this period he describes very accurately. At the expiration of the sixth or seventh month, he represents the first permanent molar as having begun to be formed in the tubercle of the 102 THE TEETH. upper jaw, and "under and on the inside of the coronoid process ot the lower;" and he states, that the pulps of the permanent central in- cisors begin to appear in a foetus of " seven or eight months, and to dentinify " five or six months after birth." The pulps of the per- manent lateral incisors and cuspids, he says, begin to be formed soon after birth ; the first bicuspids about the fifth or sixth year, the second bicuspids and molars the sixth or seventh, and the dentes sapientiaa about the twelfth year. Although Mr. Hunter gives a more minute and accurate description of the progress of the formation and arrangement of the teeth in the jaws previously to their eruption than any previous writer, yet, with regard to their origin and appearance during the earlier stages of their development, he is unsatisfactory. Nor do the researches of Jourdain, Blake, Fox, Cuvier, Serres, Delabarre, and other writers, throw much additional light upon the subject. In fact, they could not, as their researches do not seem to have been commenced at periods sufficiently early in foetal subjects; and even from the time when they were first instituted, the progress of the organs does not appear to have been traced through the subsequent stages of their formation with the re- quisite degree of care and accuracy. It is not, therefore, necessary to notice the description given by these authors of the progress of the formation of the teeth, although it may not be amiss to sta(te here, that Dr. Blake describes the rudiments of the permanent teeth as originating from the sacs of the temporary, and that this supposed discovery has been confirmed by almost every subsequent writer upon the subject.* Indeed, until quite recently, this has been the prevail- ing opinion, and their progress, step by step, from the time when the rudiments of these teeth are apparently given off as small, bud-like processes from the sacs of the temporary, is traced with a degree of minuteness by Mr. Thomas Bell that would seem to preclude the pos- sibility of deception. This last-named gentleman describes the pro- cess as commencing at a very early period of the formation of the temporary teeth, and as first perceivable " in a small thickening on one side of the parent sac," which, " gradually increasing," becomes "more and more circumscribed; until it at length assumes a distinct form, though still connected with it by a peduncle, which," he says, "is nothing more than a process of the investing sac." " For a time," continues Mr. Bell, "the new rudiment is contained within the same alveolus with its parent, which is excavated by the absorbents for its reception, by a process almost unparalleled in the annals of physiology. * It is said, but with how much truth the author is unable to say that this supposed discovery was made about, twenty years before the publication of Dr. Blake's Inaugural Dissertation, by a French dentist by the name of Herbert. THE TEETH. 103 It is not produced by the pressure of the new rudiment, as is erro- neously believed, but commences in the cancelli of the new bone, immediately within its smooth surface, thus constituting what may be termed a process of anticipation. The new cell, after being sufficiently excavated, and as the rudiment continues to increase, is gradually separated from the former one by being more and more deeply ex- cavated in the substance of the bone, and also by the deposition of a bony partition between them ; and at length the new rudiment is shut up in its proper socket, though still connected with the temporary tooth by a cord or process of the capsule already described, which has in the mean time been gradually attenuated and elongated." * Now, it would hardly seem possible for a man of Mr. Bell's accu- racy of observation, after having investigated the subject as closely and thoroughly as he must have done, to have enabled him to describe so minutely the various stages of the progress of the development of the permanent teeth, to have mistaken their origin; yet that he has would appear, by subsequent researches, to be rendered certain. I allude to those of Arnold and Goodsir. The last-named author has traced the progress of the teeth, almost from the moment of the appearance of the germs of the first set, as simple mucous papillae, until the completion of those of the second; and so minutely and accurately, that little remains to be done by fu- ture anatomists for the perfection of this branch of odontology. His investigations were commenced in an embryo at the sixth week, at which period a deep groove, formed by two „ 0_ semicircular folds, extending around each jaw, may be perceived, lined with mucous mem- brane, and as this gradually widens from be- hind forward, a ridge, commencing posteriorly and running in the same direction, rises from its floor, and divides the original groove into two others; the outer one forming the dupli- cative of mucous membrane from the inside . Fio. 28.—Upper jaw of human foetus at the sixth of the lip to the outside of the alveolar pro- week; a, The lip; b, The cess; the inner one constituting what may be Primitive dental groove. very properly denominated the primitive dental groove, as the germs of the teeth appear in it. The inner lip of the inner groove is formed by the outer edge of a * This cord has been noticed and minutely described by several other writers. Delabarre calls it the appendage of the dental matrix, and traces it through what is usually denominated the alveolo-dental canal, which he designates by the name of iter dcntis, to the surface of the gum behind the temporary teeth. He also states that it is hollow, and when he first described it in his thesis of reception in 1806, it had not been noticed by any other writer. 104 THE TEETH. semicircular lobe which is to constitute the future palate. By the seventh week after conception, the germ of the first temporary molar in the upper jaw may be seen in the primitive denial groove, rising up from the mucous membrane, lining its floor in the form of a simple free granular papilla, of an ovoidal shape, the long diameter of which is antero-posterior. By the eighth week, another papilla, of a rounded and granular form, is observable, between the mid- dle and anterior curve of the ridge, on the floor of the same groove, which is the rudiment of the temporary cuspid. Dur- ing the ninth week, the germs of the incisors—the central first, and soon after the lateral — make their appearance in the form also of mucous papillae. During the tenth week the sides of the groove before and behind the anterior molar papilla have been gradu- ally approaching each other, and processes from its side are sent off, from before and behind this germ, which meet and inclose it in a follicle. In the mean time, a similar follicle is gradually forming around the cuspid germ. Toward the end of the tenth week, the papilla of the second or posterior tempo- rary molar shows itself. The papillae of the incisor teeth, which, up to this time, have ad- vanced very slowly, now begin to increase more rapidly ; and during the eleventh and twelfth weeks, processes are sent off from the outer and inner walls of the groove, forming for each a distinct follicle, and while the papillae of the cuspid and first molar are now undergoing little change, that of the second molar is gradually increasing. During the thirteenth week, a follicle is formed for it, and a gradual change takes place in the different papillae ; each begins now to assume a par- ticular shape — the incisors, that of the future teeth — the cuspids "become simple cones,"—the molars "become flattened transversely." The papillae now "grow faster than the follicles, so that the former protrude from the mouths of the latter, while the depth of the latter varies directly as the length of the fangs of their future corresponding ; teeth." The mouths of the follicles, in the mean time, are becoming Fig. 29. Fig. 29.—Lower jaws of human embryo at the ninth week of intra-uterine life (from Kolliker), magnified nine diameters : a, Tongue thrown back; b, Right half of the lip depressed; b, Left half cut off; c, Outer alveolar wall; d, Inner alveolar wall; e, Pa- pilla of the first molar; /, Papilla of the cuspid; ff, Of the second incisor; h, Of the first incisor; i, Fold3 where the ducti Rivi- niani subsequently enter. 60 THE TEETH. 105 more developed, "so as to form opercula or lids, which correspond in some measure with the shape of the crowns of the future teeth." Of these, the incisor follicles have two — one anterior and one posterior — the first larger than the latter; the cuspid follicles have three,— one external and two internal; the molar follicles, as many as there are eminences or tubercles upon the grinding surfaces of these teeth. The outer and inner lips of the primitive dental groove have in- creased so much, that at the fourteenth week, they meet together like two valves, so as to give the papillae the appearance of receding back into their follicles, and to become almost wholly hidden by their opercula. The appearance and progress of the germs of the lower teeth and their follicles are almost precisely similar to those of the upper, though they do not appear at quite so early a period. At the epoch last mentioned, the primitive dental groove in each jaw is situated on a higher level than at first, contains the germs and follicles of the ten temporary teeth, and "may now be more properly denominated the secondary dental groove," for it is about this time that provision is made for the production of the ten anterior permanent teeth. It consists in the appearance of a crescent-shaped depression immediately behind the inner opercula of the follicles ; first, of the central incisors, next of the laterals, then of the cuspids, afterward of the first bicuspids. The opercula, in the mean time, close the mouths of the follicles, but without adhering to them; beginning with the central incisors, then continuing with the lateral, and the cuspids, and ending with the second molars. The secondary groove is now soon closed by the approach and adhesion of its lips and walls, commencing from behind and proceeding forward ; changing the follicles or pits into sacs, the papillae into the pulps of the temporary teeth, and the crescent-formed depressions into " cavities of reserve," from which the pulps and sacs of the teeth of replacement are developed. The primi- tive dental groove, which, by this time, has extended back of the second temporary molar, still retains its original appearance; it has a grayish yellow color, and its edges continue " smooth for a fort- night or three weeks longer" for the development of the papilla and follicle of the first permanent molar. The papillae of the temporary teeth are now gradually moulded into the shape of the dentine of the crowns of the teeth they are destined to form : the pulps of the upper molars are perforated by three canals, and the lower by two, which penetrate to their centre. The primary base is divided into an equal number of secondary bases, from which the roots of the future teeth are gradually to be developed. An in- tervening space is now formed between the pulps and the sacs, by the more rapid growth of the latter than the former, " in which is de- 106 THE TEETH. posited a gelatinous granular substance, at first small in quantity, and adherent only to the proximal surfaces of the sacs, but ultimately, about the fifth month, closely and intimately attached to the whole interior of these organs, except for a small space of equal breadth, all round the base of the pulps, which space retains the original gray color of the inner membrane of the follicle ; and as the primary base of the pulp becomes perforated by the canals formerly mentioned, the granular matter sends processes into them, which, adhering to the sac, reserve the narrow space described above, between themselves and the secondary bases. These processes of granular matter do not meet across the canals, but disappear near their point of junction." The granular matter, although not adhering to the pulp, is exactly moulded to all its eminences and depressions. The outer membrane of the sac, according to Mr. Goodsir, is sup- plied with blood from small twigs sent off by each branch of the dental artery at the fundus of its destined sac, and from the arteries of the gums, which inosculate with each other, and then ramify in the "true" (inner) membrane. The follicle of the first permanent molar closes about this time, and has granular matter deposited in its sac, and by the non-adhesion of the walls of the secondary groove, a cavity appears below the sac of this tooth; from the lining mucous membrane of which the second molar germ originates, and from the second sac a new offset shoots forth, destined to contain the papilla of the dens sapientice. But previously to this'period, the apices and eminences of the tem- porary teeth have become vascular, and now earthy salts begin to be deposited. Simultaneously with this process, the inner surface of the granular matter is absorbed, and after awhile becomes so thin as to render the subjacent vascularity apparent. This continues until, by the time a layer of dentine has formed over the whole surface of the pulp and reached its base, no remains of it are left. The cavities of reserve have been gradually receding and assuming a position behind the temporary teeth ; the distal extremities of the anterior ones begin to distend about the fifth month, and it is here that the germs of the teeth of replacement first appear, and are indi- cated by a bulging up or folding of this portion of these cavities. These soon acquire the appearance of dental pulps, and the mouths of the cavities gradually become obliterated. By the sixth month, bony septa have formed across the alveolar groove, and niches are now formed on the posterior walls of the al- veoli for the sacs of the permanent teeth. The sac of the first perma- nent molar remains up to the eighth, and even the ninth month im- bedded in the maxillary tuberosity. The roots of the temporary THE TEETH. 107 incisors, at or a little before birth, begin to be formed; in the accom- plishment of which, says Mr. Goodsir, " three contemporaneous actions are employed, viz., the lengthening of the pulp; the deposition of tooth substance upon it; and the adhesion of the latter to that portion of the inner sac which is opposite to it." By the time the central in- cisors appear through the gum, the jaw has lengthened so much that the first permanent molar begins to assume its proper position in the posterior part of the alveolar arch. The sacs of the permanent teeth continue to recede during the advance of the temporary teeth, and their sockets to acquire their perfect state, and to insinuate themselves between the sacs of the former until they are connected by their proxi- mal extremities only, through the alveolo-dental foramina or itinera dentium of Delabarre. Fig. 30. Fig. 30.—a, Mucous membrane; b, Mucous membrane with a granular mass deposited in it; c, The primitive dental groove; d, A papilla on the floor of the groove; e, The papilla inclosed in a follicle, and the secondary dental groove forming; /, The papilla assuming the shape of a pulp, the opercula forming, and a depression for a reserve cavity behind the inner operculum; g, The papilla becomes a pulp, and the follicle a sac by the adhesion of the lips of the opercula; the secondary dental groove in the act of closing; h, The secondary groove ad- herent, except behind the inner operculum, where it has left a shut cavity of reserve for the formation of the pulp and sac of the permanent tooth; i, The last change more complete by the deposition of the granular body, deposition of tooth substance commencing; j, The cavity of reserve receding; its bottom, in which the pulp is forming, dilating ; k, The cavity of reserve becoming a sac with a pulp at its bottom, and further removed from the surface of the gums. The temporary tooth covered with a layer of bone, and the granular substance absorbed; I, The temporary tooth acquiring its root and approaching the surface of the gums; m, Root of the temporary tooth longer, and its sac touching the surface of the gums; n, Eruption of temporary tooth, its sac again a follicle, and the permanent re- ceding further from the surface of the gum; o, Completion of temporary tooth, free portion of sac become the vascular margin of the gum, and the permanent sac connected by a cord passing through the alveolar dental canal or foramen. The vessels which go to the sacs of the permanent teeth are derived first from the gums, but they ultimately receive vessels from the tem- porary sacs, which, uniting with the others, eventually retire into permanent dental canals. The foregoing diagram, taken from Goodsir, exhibits at one view 108 THE TEETH. the origin and progress of the formation of a temporary and its cor- responding permanent tooth. The cavity of reserve, behind the first permanent molar, begins to lengthen about the seventh or eighth month ; a papilla soon appears in its fundus, it then contracts and separates from the remainder of the cavity, by which means a new sac is formed, — that of the second permanent molar. As the jaw increases in length, it comes downward and forward. The papillae of the wisdom teeth (dentes sapientiae) form in the remaining portion of the cavities of reserve, which, in the upper jaw, occupy the maxillary tuberosities, and in the lower, the base of the coronoid processes, which places, says Goodsir, they do not leave until the nineteenth or twentieth year. The progress of the formation of the three molar teeth will be seen in the diagram, (Fig. 31,) also copied from Mr. Goodsir. Fig. 31. Fig. 31.—a, The non-adherent portion of the primitive dental groove; b, The papilla and follicle of the first molar on the floor of the non-adherent portion, now become a portion of the secondary groove; c, The papilla a pulp, and the follicle a sac, and the lips of the secondary groove adhering, so that the latter has become the posterior or great cavity of reserve; d, The sac of the first molar increased in size, advancing into the coronoid process or maxillary tuberosity, and the cavity of reserve lengthened; e, The sac of the first molar returned by the same path to its former position, and the cavity of reserve shortened; /, The cavity of reserve sending backward the sac of the second molar; g, The sac of the second molar advanced into the coronoid process or maxillary tuberosity; A, The second molar sac returned, and the cavity of reserve shortened; i, The cavity of reserve sending off the sac and pulp of the wisdom tooth; j. The sac of the wisdom tooth advanced into the coronoid process or maxillary tuberosity; k, The sac of the wisdom tooth returned to the extremity of the dental range. From the foregoing abridgment of the description given by Mr. Goodsir, of the development of the pulps and sacs of the human teeth, it is seen that the papilla of the first temporary molar makes its appear- THE TEETH. 109 ance at about the seventh week of embryonic life; at the eighth week, the cuspid papilla is developed; during the ninth, the papillae of the incisors make their appearance, and by the end of the tenth week, the papilla of the second temporary molar may be seen. At the end of the fourteenth week, the upper part of the primitive dental groove, containing the germs and follicles of the ten temporary teeth, becomes the secondary dental groove, from which the papillae of the teeth of replacement are furnished. The secondary groove assumes the form of crescent-shaped depressions behind the palatine opercula of the fol- licles of the temporary teeth. The cavities of reserve for the perma- nent teeth gradually recede, and assume a position behind the sacs of the deciduous teeth, and from the distal extremities of these the papillae of the replacing teeth are developed. It is only necessary to add to the description of this process already given, the further statement that the papillae are little oval masses of cells resembling epithelial cells which have had their origin in pre- existing cells, that the follicle is simply an investing fold of mucous membrane. The young tooth then begins in the midst of cells which had their origin in a pre-existing epithelial-like cell, which has grown and multiplied by division. It is everywhere surrounded by cells, and is without basement membrane or sub-basement tissue, and no line of demarcation exists between what shall finally be epidermic and dermic tissues. "It is certain that an elevation or 'papilla' occurs when a tooth is to be formed; but I think that in the central part of these lpapillai^ which consist of collections of cells, new ones appear, and that this process continues, until at last the tooth structure commences to be formed in the last collection of cells in the central part. I consider that the dental 'papilla' is entirely composed of modified epithelium, developed from what may be termed an epithelial cell. The collection of cells afterward becomes inclosed in its sac by the growth of the mucous membrane over it." (Beale On the Structure and Growth of Tissues, p. 189.) From these cells is formed a soft matrix of animal matter, which becomes impregnated with calcareous matter to form the complete den- tal tissue, whilst in the interior of the cavity of the dentine, cells are found which continue to form new matrix for a considerable time. Vessels cannot be traced to the cells in which the tooth is growing until it has attained a considerable size, and the formation of the fang has commenced. THE PULP. The pulp, occupying the pulp cavity in the centre of the tooth, is the shrunken condition to which the tooth-germ is permanently re- 110 THE TEETH. duced after it has normally accomplished the work of dentinification. It is an exquisitely sensitive, highly vascular substance, of a reddish- gray color, enveloped in an exceedingly delicate, and apparently structureless membrane, continuous with the alveolo-dental periosteum, and adherent to the walls of the pulp cavity. This is designated by Mr. Thomas Bell "the proper membrane of the pulp," and by Pur- kinje and Raschkow, " the preformative membrane; " because, in the Fig. 32. Fig. 33. Fig. 32.—A portion of the body of the pulp, showing the cellular arrangement. Fig. 33.—A portion of the superficial layer of the pulp, showing the appearance of vesicles. formation of the dentine, the deposition of earthy salts, according to these authors, commences in it. The pulp, according to the two last mentioned authors, is composed of minute globules. Schwann describes it as consisting of globular nucleated cells, with vessels and nerves passing between them, the cells having the same radial course as the fibres of the dentine. Accord- ing to the microscopic observations of Mr. JNasmyth, it is principally composed of minute vesicular cells, varying in size from the ten- thousandth to the one-eighth of an inch in diameter, disposed in concentric layers; these, when macerated, have an irregular reticulated appearance, and are found to be interspersed with granules, the paren- chyma being traversed by vessels having a vertical direction. See Figs. 32 and 33, copied from M#. Nasmyth's Researches on the Development and Structure of the Teeth. Mr. Tomes describes it as consisting, from its earliest appearance, of a series of nucleated cells, united and supported by plasma; also, prior to the commencement of the formation of the dentine, of delicate areolar tissue, occupied by a thick, clear, homogeneous fluid or plasma. The pulp is liberally supplied with bloodvessels, furnished by the trunk which enters its base. The ramifications of these vessels are distributed throughout its entire substance, forming a capillary net- work which terminates in loops upon its surface. The distribution of the vessels of the pulp is represented in Fig. 34, THE TEETH. \\\ copied from the late work of Mr. Nasmyth, and made from an in- jected preparation of an upper central incisor. The communication of the arteries with the veins by means of a series of looped capillaries, presenting a densely matted appearance upon the surface, are beauti- fully represented. The nerves of the pulp have a very similar arrange- Fig. 34. Y' 3.4,~"' ,n0 vessels of the pulp of an upper central incisor injected, as seen "1- Dr. Maynard had been able to procure in relation to this case were contained in the patient's state- ment: "That in 1818 he took a cold, which settled in his upper jaw, and a large piece of the jaw-bone came away." The cast from which the drawing was made was taken in 1840; at which time the doctor cut off the apices of several roots which projected from the gums. Phosphor-Necrosis. — Necrosis of the bones of the jaws may also result from exposure to the fumes of phosphorus, as in the manu- facture of matches, for example. The disease, when due to such a cause, usually commences about a carious tooth, or in an alveolar cavity opened by the extraction of a tooth, and is sometimes complicated with affections of the lungs and air passages. In phosphor-necrosis there is a peculiar pasty appearance of the face, puffiness of the cheeks, and considerable pain and swelling in the affected jaw. Instead of the separation of a sequestrum, the dead bone becomes incrusted with a pumice-stone like material, which adheres very firmly to it. Abscesses form and discharge externally through the skin of the cheek, and leave fistulous openings for the escape of the matter. + CAUSES. The immediate cause of necrosis is the death of the periosteum, occa- sioned by inflammation. The cause of this, as has already been shown, is, in a large majority of the cases, dental irritation. Necrosis of the alveolar process occurs very frequently while the system is under the influence of mercurial medicines, and during bilious and inflammatory fevers, and certain other constitutional diseases, as syphilis, small-pox, etc. It may also result from mechanical injuries. 244 ABSORPTION OF THE ALVEOLI. TREATMENT. The treatment of cases of this kind consists in the removal of the sequestra, strict attention to cleanliness, and the free use of chlorinated washes. As soon as the dead portions of bone become separated from the living, and can be easily removed, they should be taken away with a pair of forceps. Should the removal of a considerable portion of the bone of the jaw be requisite, it is seldom necessary to interfere with the skin, or make an external incision. The whole of the lower jaw can be removed in this manner by dividing it at the chin, and after separating all the attachments of the soft parts with the knife, drawing out each half at a time. To correct the offensive odor and disagreeable taste occasioned by the constant discharge of fetid matter, washes of chloride of soda, or chloride of zinc, or of the tincture of myrrh, may be employed. Should constitutional symptoms supervene, tonics, a nutritious diet, and such other remedies as have a tendency to restore the general health, are of the greatest service. CHAPTER XIII. ABSORPTION OR GRADUAL DESTRUCTION OF THE ALVEOLAR PROCESSES. WHILE treating of inflammation and tumefaction of the gums, the author adverted to the wasting of the sockets of the teeth, taking occasion to express a doubt that such operation of the economy ever manifested itself in the absence of all local disease. It is always accompanied by a slight increase of redness, tumefaction, and a shrinking of the edges of the gums (ulatrophia) ; but the diseased action here is so inconsiderable as often to attract little attention. It is also attended by a slight discharge of purulent matter from between the margin of the gum and the tooth ; but the quantity is so small that it usually escapes observation. The alveolo-dental periosteum partici- pates also in the diseased action, but this is so slightly aftected that the tooth often remains quite firmly articulated, after the wasting of its socket has proceeded even so far as to expose more than half of the root. Indeed, the affection is so closely allied to chronic inflammation and tumefaction of the gums, as scarcely to require separate considera- tion. ABSORPTION OF THE ALVEOLI. 245 The progress of the disease is usually so slow that ten, fifteen, or twenty years are required to affect very perceptibly the stability of the teeth in Fig. 52. their sockets. The commencement of this destructive process is usually first observed around the cuspid teeth; sometimes it makes its first appearance on the alveoli of the palatine roots of the first and second upper molars, and occasionally it goes on here for years before it affects the sockets of any of the other teeth. The teeth, after their roots have been partially exposed, become, as might naturally be supposed, more susceptible to impression from heat and cold, and more easily affected by acids, or saccharine matters; but this is about the only manifest inconvenience experienced from the disease, until the teeth begin to loosen in their sockets. In Fig. 52 is represented a case in which the roots of the teeth have become considerably exposed by the gradual wasting of their sockets, — the destruction being, as is usual, greatest toward the median line. CAUSES. The cause of this peculiar affection has never been very satisfactorily explained. Some have supposed that, inasmuch as it occurs most fre- quently in persons of advanced age, it results from a decline of the vital powers of the body, independently of local causes. But, as it is often met with in middle-aged persons whose constitutional health is unimpaired, we doubt the correctness of the opinion. In all cases which have come under our observation, whether in middle-aged or very old persons, the teeth indicated an excellent innate constitution, whatever may have been the state of the general health at the time. In every instance these organs were possessed of great density, and this fact is particularly noticed by Mr. Fox, who says: " In a majority of cases in which this disease occurs, the teeth are perfectly sound, and from numerous observations, we think we may ven- ture to assert, that persons who have had several of their teeth affected with caries in the earlier part of life, are not liable to lose, by an ab- sorption of their sockets, those which remain sound ; but, where the teeth have not been affected with caries in the early part of life, persons. as they approach the age of fifty, and often much earlier, have their teeth becoming loose from absorption, or a wasting of the alveolar process." Now it is evident that teeth endowed with the power of resisting to so late a period of life the action of the causes of decay, to which all teeth are more or less exposed, must be possessed of extreme density, 246 ABSORPTION OF THE ALVEOLI. and, necessarily, a corresponding low degree of vitality. In view of this fact, Ave have been led to the opinion that the teeth themselves may act, to some extent, as mechanical irritants to the more highly vitalized parts with which they are immediately connected, causing an increase of vascular action in the periosteum of the thin edges of the alveoli and margin of the gums. This abnormal condition is attended by a slight secretion of purulent matter observed between the edges of the gums and teeth. It is to the corrosive action of this purulent matter that the gradual destruction of the alveoli has by some been attributed; but it is more probably a result of the obscure disease than its cause. We were for a long time inclined to ascribe the increase of vascular action in the edges of the gums and alveolo-dental periosteum to irritation produced by the pressure of the teeth against the alveolar septa; but having met Avith many cases Avhere the teeth Avere not crowded, Ave Avere induced to enter into a more thorough examination of the possible causes, and the foregoing is the only conclusion to Avhich we have been able to arrive. This affection may also sometimes result from the. presence of salivary calculus, the use of charcoal powder as a dentifrice, and the application of a very stiff brush for cleaning the teeth; but when caused by these two latter agents, the absorption does not progress to such a degree as Avhen it is OAving to a Avant of congeniality between the tooth and the more highly vitalized structures surrounding its root. TREATMENT. From Avhat has been said concerning the cause of this affection, it is obvious that a cure cannot ahvays be effected. The progress of the affection, however, may sometimes be arrested. The first step in the treatment is to remove all irritants, and correct the nature of the fluids of the mouth, abnormal in character, by constitutional treatment, the use of lime-water, and a detergent dentifrice. Should such means prove ineffectual, the application of a solution of iodine and creosote or carbolic acid to the margins of the gums will often be of benefit in retarding the absorption, and inducing a more healthy actpn. The secretion of the purulent matter, to the action of which some attribute the destruction of the alveoli, is the result of a disease in the alveolo- dental periosteum and edges of the gums, arising from some peculiar physical condition of the teeth, the progress of Avhich may be retarded by cleaning the teeth frequently and thoroughly, using the precaution each time to remove the purulent matter from between the edges of the gums and teeth, lest, if allowed to remain, it should become putres- cent, and in this condition act as an irritant to the gum. For this purpose a brush with elastic bristles should be used, and much benefit HYPERTROPHY OF ALVEOLAR CAVITIES. 247 will be derived by passing floss silk several times a day up and doAvn between the teeth, and applying a solution of nitrate of silver, twenty grains to the ounce of Avater, by means of a camel's-hair brush, to the margins of the gums. When salivary calculus causes the recession of the gum, the first indication is the removal of this deposit. As the margin of the gum is inflamed, and a sulcus or pocket formed between it and the tooth, an incision should be made from the bottom of this sulcus upward, and the tooth surface cleaned and polished. This treatment should be followed by the application of carbolic acid, on a thin strip of orange Avood, to the inner surface of the margin of the gum to promote healthy granulations. CHAPTER XIV. HYPERTROPHY OF THE WALLS OF THE ALVEOLAR CAVITIES. A TOOTH is sometimes slowly forced from its place by a deposit of bony 'matter in the bottom or on the side of the socket. Two, or even three teeth, may be gradually displaced, at the same time, by exostosis of the alveoli. The deposition usually proceeds so slowly that one or tAvo years are required to effect a very perceptible change in the situation of a tooth. The upper central incisors are more fre- quently affected than any of the other teeth, and the deposit occurs oftener at the bottom than on the sides of the alveoli. In the first case, the tooth is gradually protruded from the socket; in the other, it is either pressed out of the arch, or against one of the adjoining teeth. Irregularity in the arrangement of the teeth is, in this manner, sometimes produced, especially Avhen more than one socket is affected at the same time. The central incisors are sometimes forced apart; at other times they are forced against each other, and caused to over- lap. The deposition of bone, however,.being generally confined to the bottom of the sockets, the teeth are more frequently thrust from their alveolar cavities. When this occurs with a person Avhose upper and lower teeth strike directly upon each other, it occasions much incon- venience ; for the elongated tooth must either be throAvn from the circle of the other teeth, or, by striking its antagonist, prevent the jaAvs from coming together. CAUSES. So little is known concerning the cause of exostosis of the sockets of the teeth, that it may seem almost useless to attempt an explanation 248 ATROPHY OF THE TEETH. of it. That it results from some irritation of the lining membrane is very generally believed, but Avhat causes the irritation does not seem to be well understood. We have thought that it might sometimes be produced by pressure on the bottom of the alveolus, especially when the extremity is nearly as large as any other part of the root of the tooth. The susceptibility of the lining membrane to morbid impres- sions may sometimes be so great that the pressure of a very conical root may be sufficient to produce this effect; or, it may be produced by the pressure of a tooth which possesses only a very low degree of vitality. But in connection with this class of cases must be taken another, in Avhich absence of all pressure would seem to be an inciting cause of alveolar exostosis; as where a tooth has lost its antagonist tooth or teeth, and in consequence becomes elongated. A diseased state of the gums can have no agency in the production of the exosto- sis, for it most frequently occurs in individuals whose gums are per- fectly healthy; and if it Avere the result of any constitutional tendency, all the teeth Avould be as likely to be affected by it, as those Ave have mentioned. TREATMENT. When the exostosis is on the side of the alveolar cavity, the tooth cannot be restored to its natural position ; but when it is in the bottom of the socket, the elongated organ may from time to time, as it is forced from the alveolus, be filed off even with the other teeth; but in doing this, care should be taken to avoid as much as possible the un- pleasant jar which the file is so apt to cause, and Avhich might, in such cases, excite the periosteum to increased activity and a more rapid deposit. This will remove the deformity and prevent its displacement by the antagonizing tooth. By this simple operation, repeated as oc- casion may require, it is preserved for years, and rendered almost as useful as any of the other teeth. CHAPTER XV. ATROPHY OF THE TEETH. THAT peculiar structural alteration of the teeth designated atrophy, is less frequent in its occurrence than any other disease to which these organs are liable; but as the progress of the affection usually terminates with the action of the causes concerned in its production, it has scarcely been deemed of sufficient importance to merit serious ATROPHY OF THE TEETH. 249 consideration. Hence its etiology and pathology have not been very carefully investigated. Indeed, most writers upon the diseases of the teeth have overlooked the affection altogether ; Avhile a few have merely alluded to it, without describing the characteristics of even its princi- pal varieties. Whether Ave shall now be able to throw any additional light upon the subject, or establish the correctness of any opinions already advanced, we leave to others to determine. The strict applicability of the term atrophy may, perhaps, be con- sidered as somewhat questionable ; as the two principal varieties of the affection consist in a congenital defect in some portion of the enamel of two or more teeth, rather than in the wasting, for Avant of nourish- ment, of any of the dental tissues. This term would seem to be ren- dered still more inappropriate by the fact that neither of the A'arieties to which we have referred occurs subsequently to the formation of the enamel. But as the congenital form of the disease is evidently the result of altered function in a portion of one or more of the formative organs — if not of absolute degeneration, from vicious nutrition — Ave are disposed to regard the term as the most applicable of any that can be applied to it. Maury treats of atrophy and erosion as one and the same disease. But in describing atrophy he notices the distinctive peculiarities by which each affection is characterized.* In describing the difference betAveen erosion and atrophy, M. Delabarre says, the part atrophied is deformed and deprived of the enamel, and that the teeth are yellow and sensitive, the touch of the finger causing pain ; but in erosion, if the crystals of the enamel are not wholly destroyed, the bottom of the pits are of a Avhite color, and on being touched no disagreeable sensa- tion is experienced; if, on the contrary, the crystals are destroyed to the dentine, the part thus denuded is irritable. In an article on erosion, Maury gives a very accurate description of several varieties of atrophy of the teeth. The first, he represents as consisting of deep irregular white, or light yellow spots, situated in the enamel of the tooth, Avithout affecting the smoothness of its surface. The second, as characterized by small crowded holes, or irregular de- pressions, resembling quilting; or as consisting of transverse sinuosities, single or divided by prominent lines, which are sometimes "yellow, but of the color of the enamel." The third variety affects the dentine as well as the enamel, reducing the dimensions of the crown of the tooth sometimes to one-third its natural size, and not unfrequently dividing it by a deep circular groove or depression. None of the phenomena here described are produced by the action of corrosive agents, or are the result of chemical decomposition either * Traite" Complet de l'Art du Dentiste, pp. 99 and 100. 250 ATROPHY OF THE TEETH. of the enamel or dentine, but are manifestly dependent upon other causes. The term erosion, therefore, cannot with propriety be applied to either variety of the affection just noticed. Although Maury has given, under the term erosion, a better description of the principal varieties of dental atrophy than any other writer, he has omitted some things Avhich it will be proper to mention. In treating of these different varieties, therefore, we shall change, somewhat, the order in which he has arranged them. Odontatrophia may very properly be divided into three varieties. Each has characteristic peculiarities Avhich distinguish it from either of the others. Tavo are always congenital, and the other, although most frequently congenital, sometimes occurs subsequently to the erup- tion of the tooth. First variety.—The peculiarities that distinguish this variety of atrophy from either of the others are, that it never impairs the uni- formity and smoothness of the surface of the enamel, and is character- ized by one or more white, or dark, or light broAvn, irregularly shaped spots, upon the labial or buccal surface of the tooth. It occurs oftener than the third variety, and less frequently than the second. It rarely appears on more than one or two teeth in the same mouth, though several are sometimes marked by it. It is seen on the molars more frequently than the bicuspids, and much oftener on the incisors of the upper jaw than any of the other teeth. We do not recollect to have ever observed it on the cuspids of either jaAV, nor on the palatine or lingual surfaces of the incisors. The enamel is much softer on the affected than on the unaffected parts of the tooth, and may be easily broken and reduced to poAvder with a steel instrument. It seems to be almost Avholly deprived, in these places, of its animal constituents, and to have lost its connection Avith the subjacent dentine, The size of the atrophied spots are almost as variable as their shape, but the only harm resulting from them is the unsightly aspect they sometimes give to the tooth. As we have before remarked, this variety of atrophy is sometimes accidental, occurring subsequently to the eruption of the tooth, but in a large majority of the cases it is congenital. It is rarely seen on a temporary tooth. In all the cases AA'hich have come under our observa- tion, it was confined, to the best of our recollection, to the teeth of second dentition. Second variety. — This may be very properly denominated perforating or pitting atrophy ; it gives to the enamel an indented or pitted appear- ance, the irregular depressions or holes extending transversely across and around the tooth. The pits are sometimes more or less distinctly separated one from another by prominent lines ; at other times they ATROPHY OF THE TEETH. 251 are confluent, and form an irregular horizontal groove. Sometimes they penetrate but a short distance into the enamel; at other times they -extend entirely through it to the dentine. Their surface, though generally rough and irregular, usually presents a glossy and polished appearance — a peculiarity Avhich always distinguishes this variety of the affection from erosion. The pits often have a dark-broAvnish ap- pearance, though sometimes they have the same color as the enamel on other parts of the tooth. This variety of atrophy is never confined to a single tooth. Two, four, six, or more corresponding teeth are always affected at the same time in each jaw; and the corresponding teeth on either side precisely in the same manner and in the same place. When more than two are marked, the distance of the pits from the coronal extremity of the tooth varies, according to the progress made in the formation of the enamel at the time of the operation of the causes concerned in the pro- duction of the affection. For example, Avhen the line of pits in the central incisors is situated about two lines from their cutting edges, it Avili scarcely be one line from the cutting edges of the laterals, and only the points of the cuspids will be marked. When the indentations are nearer the edges of the central incisors, they will be on the edges of the laterals, and the cuspids will have entirely escaped. Sometimes the teeth are marked Avith two or three rows of pits, and Avhen this is* the case, the patient has either tAVO or three relapses ; or has been attacked two or three times in succession with some disease capable of interrupting the progress of the formation of the enamel. Although the incisors are more frequently marked Avith these inden- tations than any of the other teeth, the cuspids, bicuspids, and even the molars, are sometimes affected with them. When the disease at- tacks the molars, its effects are generally located on the grinding sur- face. The permanent teeth are more liable to be attacked than the temporary. We have known but one instance in Avhich the latter Avere affected Avith the disease. This variety of atrophy occurs oftener than either of the others, and though it sometimes gives to the teeth a disagreeable and unsightly appearance, it rarely increases their liability to decay. Third variety.— In this variety of atrophy the Avhole or only a part of the ci'Oavj of a tooth may be affected ; the dentine being often im- plicated as well as the enamel. The tooth usually has a pale yelloAV- ish color, a shrivelled appearance, and is partially or Avholly divested of enamel. Sometimes the croAvn is not more than one-half or one- third its natural size. Its sensibility is usually much increased, and its susceptibility to pain from external impressions is wonderfully ex- cited by acids. It is also more liable than the other teeth to be 252 ATROPHY OF THE TEETH. attacked by caries. The root of the tooth is sometimes, though rarely, affected, and presents an irregular knotted appearance. The disease is often confined to a single tooth, but it more frequently shows itself on two corresponding teeth in the same jaw. According to our observation, the bicuspids are more liable to be attacked than any of the other teeth. The temporary teeth are rarely affected with it. This variety of atrophy occurs less frequently than either of the others; and, although it increases the liability of the affected organs to caries, they sometimes escape until the tAventieth or thirtieth year of age. In the description Avhich Ave have given of the three varieties of dental atrophy, Ave may have omitted to mention some of the pecu- liarities belonging to each, but Ave have pointed out their principal characteristics with sufficient accuracy to enable them to be distin- guished one from another, and either from erosion. CAUSES. The first variety is evidently produced by some cause capable either of preventing or destroying the bond of union between the enamel and subjacent dentine, but Avhat that cause is, becomes a question Avhich it may be difficult to answer. Subsequently to the eruption of the teeth, it may be occasioned by mechanical violence, but we have never known more than one case in Avhich it had resulted from this cause, and that was occasioned by a Woav upon the tooth. Now, whether the bond of union between this portion of the enamel and the subjacent dentine was immediately destroyed by the concussion of the blow, or Avhether it resulted from subsequent inflammation and the death of the intermediate membrane, is a question which may not be easily answered. If it Avere destroyed at once by the blow, one might be led to suppose that the change in the color of the enamel would have been observed immediately ; but it may have resulted from some subsequent change or alteration in the animal constituents of this part of the enamel, following as a consequence of the injury produced by the violence of the blow. These are questions, however, which the present state of our knowledge does not enable us to solve. But that the white spot in this case resulted as a consequence of the bloAv, there cannot be the least shadoAV of doubt. When the affection is congenital, as it almost always is, it is de- pendent upon some other cause; possibly upon disease in the pulp, or intermediate membrane, which constitutes the bond of union between the dentine and enamel, subsequently to the formation of the latter. But what the determining cause is of the disease, Avhether produced in this way by simple local irritation, or by general constitutional dis- ATROPHY OF THE TEETH. 253 turbance, Ave are not prepared to say. One would be likely to suppose, if the atrophied spots were occasioned by disease of the pulp or inter- mediate membrane, the morbid action would scarcely confine itself to such narrow and circumscribed limits. But, whether the destruction of the intermediate membrane of the affected parts results as a conse- quence of actual disease, or merely from vicious nutrition, or Avhether from unknown causes it has failed to be developed here, it is certain that the fibres of this portion of the enamel are not united to the suta jacent dentine ; thus, not receiving a supply of nutrient fluid or vital principle, their animal frame/work partially or wholly perishes, leaving but little else than their inorganic constituents. The cause of this variety of congenital atrophy, it must be confessed, is very obscure; and, in the absence of positive knowledge, Ave can only infer the cause from the nature of the affection. If it does not result from one or other of the above-mentioned causes, it is difficult to imagine in Avhat Avay it is produced. The cause of the second variety of odontatrophia is, Ave think, sus- ceptible of a "more satisfactory explanation. The formative organ of the enamel, as is now generally admitted, consists of a membrane, com- posed almost Avholly of short hexagonal corpuscles or fibres, Avhich cor- respond in shape and arrangement to the fibres of the enamel. This membrane is accurately moulded to the croAvn of the tooth, and, according to Raschkow, each fibre is a secretory duct, Avhose peculiar function it is to secrete the fibre of the enamel corresponding to it. It should also be borne in mind that the secretion of the earthy salts of the enamel commences at the coronal extremity of the tooth, gradually proceeding toward the base of the croAvn. Now Ave can readily con- ceive that some constitutional disease might interrupt the secretion of the earthy salts deposited in the enamel-cells or secretory ducts of the enamel membrane, for the formation of the enamel fibres; occurring at the time when this process is going on, it might prevent them from being filled, and cause them to wither or Avaste away, giving to this portion of the enamel the pitted appearance Avhich characterizes this variety of atrophy. In other Avords, the secretion of the inorganic con- stituents of the enamel being interrupted for a short time the horizontal row of cells in the enamel membrane, into which it should be deposited, Avill not be filled; consequently, as might readily be supposed, they will waste away, leaving a circular toav of indentations around the crown of the tooth. But as soon as the constitutional disease has run its course, the secretion of the earthy salts Avillbe resumed; and unless the child experiences a relapse, or has a second attack of disease, capa- ble of interrupting this secretory process, the other parts of the enamel will be well formed. 254 ATROPHY OF THE TEETH. Some writers ascribe the formation of these pits in the enamel to the chemical action of a corrosive fluid, or to an acidulated condition of the fluid contained in the dental sacs; but they have evidently con- founded this affection with erosion. We believe, however, it almost always occurs as a consequence of some eruptive disease or catarrhal fever occurring during the " enamelling " process ; and there are many facts which go to sustain the correctness of this opinion. In nearly all the cases that have fallen under our observation, it Avas clearly traceable to measles, scarlatina, chicken-pox, catarrhal fever, or small- pox. It may, however, occasionally be produced by other constitutional diseases. The third variety of dental atrophy, so far as our observation upon the subject has permitted us to form an opinion, always results from altered or vicious nutrition, caused by disease of the pulp or enamel membrane, or both, during the secretion of the dentine or enamel, accordingly as one or both are affected. We are inclined to believe that the disease in the dental pulp or enamel membrane may be pro- duced either by local or constitutional causes, or both. But the infor- mation Avhich we have been able to obtain in the cases that Ave have seen, concerning the state of the general health, and that of the mouth at the time of the dentinification of the pulp and the secretion of the enamel, has not been as satisfactory as we could have Avished. Since writing the foregoing, the following interesting case of dental atrophy has fallen under our observation: Mrs. C. called, in 1850, to consult us concerning her daughter's teeth, which, from congenital defect, presented a most unsightly appear- ance. The girl Avas between nine and ten years of age. The cutting edges of the upper central incisors Avere badly pitted and very rough; the corresponding teeth in the lower jaw had a transverse row of pits passing around them, about a sixteenth of an inch beloAV their cutting extremities. Another row of pits, so close together as to form a rough groove, encircled the upper central incisors, about an eighth of an inch below the gum, and the laterals a little nearer their cutting edges; the lower incisors Avere similarly marked, but not quite so near the gum. The enamel, near the second transverse toav of pits, and between it and the cutting edges of the teeth, was thin and of a light-brown color. A little above the first toav, on the central incisors, Avere tAvo or three brown or opaque spots. The first permanent molars Avere also encircled with a row of indentations, about half-way between their grinding surfaces and the gums. On inquiry, Ave learned from the mother that the child had a light attack of measles when between eleven and tAvelve months old, of NECROSIS OF THE TEETH. 255 scarlet fever Avhen about fifteen or sixteen months of age, and dysen- tery at about the twenty-first or tAventy-second month. Now, here Ave haAre the three varieties of atrophy on the same teeth; and the occurrence of constitutional diseases about the time when the affected parts of the teeth must have been receiving their earthy salts, would seem to establish very conclusively the connection of the one with the other. TREATMENT. The nature of this affection is such as not to admit of cure. The treatment, therefore, must be preventive rather than curative. All that can be done is to mitigate the severity of such diseases as are sup- posed to produce it, by the administration of proper remedies. By this means their injurious effect upon the teeth may, perhaps, be par- tially or wholly counteracted. It seldom happens that atrophied teeth decay more readily than others, so' that the only evil resulting from the affection is a disfigura- tion of the organs. When the cutting edges of the incisors only are affected, the diseased part may sometimes be removed Avith a file with- out injury to the teeth. CHAPTER XVI. NECROSIS OF THE TEETH. BY the term necrosis, when applied to a tooth, is meant the death of the entire organ, or of the crown and inner Avails of the root; for it often happens that a degree of vitality is kept up in the outer portion of the dentine and the investing cementum by the peridental membrane long after the destruction of the pulp and lining membrane. When other bones are affected with necrosis, the dead part is thrown oil'and the loss supplied by the formation of new bone. But the teeth are not endowed Avith the recuperative poAver which the process of exfoliation calls for. The density of a tooth is not sensibly, if at all, affected by the mere loss of vitality; but so great a change takes place in the appearance of the organ, that it may readily be detected by the most careless ob- server. After the destruction of the lining membrane, the tooth gradually loses its peculiar semi-translucent and animated appearance, assuming a dingy or muddy broAvn color; and this change is more striking in teeth of a soft than in those of a hard texture. The dis- 256 NECROSIS OF THE TEETH. coloration, too, is always more marked Avhen the loss of vitality has resulted from a blow, than when produced in a more gradual manner. The discoloration is partly owing to the presence of disorganized mat- ter in the pulp-cavity, and partly to the absorption of this matter by the surrounding Avails of dentine. After the destruction of the lining membrane, the tooth may receive a sufficient amount of vitality from the alveolo-dental periosteum to prevent it from exerting a manifest morbid influence upon the parts with which it is immediately connected. Teeth have been retained under such circumstances Avith apparent impunity for fifteen or twenty years. But Avhen every part of a tooth has lost its vitality, it becomes an extraneous body. When this happens, inflammation of the socket ensues, the gum around it becomes turgid and spongy, and bleeds from the slightest injury, and the organ gradually loosens and ultimately drops out. In the mean time, the diseased action frequently extends to the sockets and gums of the adjoining teeth. The front teeth, being more exposed to injuries from violence, are more liable to necrosis than the molars. CAUSES. Necrosis of the teeth may be produced by a variety of causes, such as protracted fevers, the long-continued use of mercurial medicines; by caries, and by external violence. The immediate cause, however, when not occasioned by a blcnv sufficient to destroy the vascular con- nection of the tooth with the rest of the system, is inflammation and suppuration of the lining membrane; but it may result from deficiency of vital energy and from impaired nutrition; for the author has met with several cases in which the loss of vitality could not be accounted for in any other way. , TREATMENT. When a tooth, deprived of vitality, is pKoductive of injury to the gums and to the adjacent teeth, it should be immediately removed; for, however important or valuable it may be, the health and dura- bility of the others should not be jeopardized by its retention. When necrosis of a tooth is apprehended, Ave should endeavor to prevent its occurrence, by the application of leeches to the gums, and by gargling the mouth with suitable astringent washes. If this plan of treatment is adopted at an early period, it will sometimes prevent the loss of vitality; but if long neglected, a favorable result need not be anticipated. When the loss of vitality is confined to the crown and inner Avails of the root, if the former is not seriously impaired by caries, it may NECROSIS OF THE TEETH. 257 be perforated, and the pulp-cavity and root cleansed and filled in the maimer as directed in another part of this Avork. If the necrosed tooth is an incisor, the perforation should be made from the palatine surface, provided the approximal surfaces are sound. But previously to the introduction of a filling, the decomposed surface of the Avails of the pulp-cavity should be completely removed, and if this does not restore the tooth to its natural color, the process of bleaching should be resorted to. Bleaching Necrosed Teeth.—To improve the appearance of a necrosed tooth Avhich has become discolored from the dentinal tubuli absorbing the coloring matter from the blood, the following method may be pur- sued : First, remove all decayed matter from the crown cavity, where such a cavity exists, taking care, however, to leave the enamel unin- jured, and also as much of the dentine as is necessary for the strength of the tooth. Pursue the same course Avith regard to the canal in the root, cleansing this carefully by means of a syringe and tepid water, after the removal of decomposed matter with the nerve canal instruments. When the discoloration is recent, and not more than a red tinge in degree, such treatment as has been described may prove sufficient; should it not be, hoAvever, OAving to the length of time the discoloration has existed, and the hue is a brown, dark-broAvn or black, it is then necessary to resort to such agents as contain chlorine. Solu- tions of chloride of soda, chloride of lime, chlorate of potash, decompose organic substances by removing the hydrogen of their coloring matter. One of the most reliable of these preparations is the solution of chloride of soda, known as " Labarraque's Disinfecting Fluid," Avhich may be introduced on a pellet of cotton, and allowed to remain in the tooth from thirty to sixty minutes, according to the degree of discoloration present. Repeated applications may be necessary in some cases before the object desired is accomplished. To prevent the caustic action of these agents on the soft parts, the canal in the root should be partly filled prior to their introduction, and care taken to prevent their com- ing in contact Avith the mucous membrane of the mouth. The chloride of lime is introduced in the same manner as the chloride of soda, and is allowed to remain for five, ten, or fifteen minutes at a time, and its application repeated if necessary, the crown cavity during the interval being protected by a temporary filling of Hill's stopping. 17 258 EXOSTOSIS OF THE TEETH. CHAPTER XVII. EXOSTOSIS OF THE TEETH. THIS disease is common to all bones, but it attacks no other part of a fully formed tooth than the root; for in the cementum alone, of the three osseous dental tissues, do Avefind that degree of vascularity which is a necessary condition of groAvth,— normal or abnormal. It usually commences at or near the extremity, then extends upward, covering a greater or less portion of the external surface. It some- times, however, commences upon the side of the root and forms a large tubercle; at other times the deposit of the neAV bony matter is spread over its surface, often uniformly, but more frequently unequally. The osseous matter thus deposited, has usually the color, consistence, and structure of the cementum, though sometimes it is a little harder and assumes a yelloAver tinge. The enlargement is in fact an hypertrophied condition of this substance. Those singular anomalies, occasionally met with, where enamel, dentine, and cementum are mixed up in shape- less confusion, are no exceptions to the rule that exostosis is confined to the cementum ; for though classed under this head, these cases arise from disruption of the formative membranes (possibly the result of violence), each secreting its pecu- FlG- 53- liar tissue. The hypertrophy is probably confined to the dentine; yet it is quite possible for the den- tinal and enamel membranes in their then vascular condition to have an excess of development. The deposit of osseous matter is sometimes so considerable, that the roots of two or more teeth are firmly united by it. Fig. 53 rep- resents several examples of exo- dontosis of this description. One of these Avas presented to the author by Drs. Blandin and Reynolds, These, Avith many other remarkable cases, including one presented by Dr. Hawes, in which three teeth are thus united, may be seen in the Museum of the Baltimore College of Dental Surgery. of Columbia, South Carolina. h ■*'<■ EXOSTOSIS OF THE TEETH. 259 An extraordinary case of dental exostosis Avas sent to the author for examination, by Dr. V. M. Swayze, of Easton, Pa. The tooth appa- rently is a dens sapientise, and the formation of the exostosis must have commenced Avith the dentinification of the pulp. It had spread over every part of the tooth, the crown as well as the root; it had ruptured and penetrated every part of the enamel membrane, but had not Avholly destroyed the function of this organ, as nodules of enamel are seen in various parts of the exostosis. The tumor, including the tooth, is about as large as a common sized hickory nut. Exodontosis often continues for a long time Avithout producing any inconvenience Avhatever. It usually first manifests itself by slight sore- ness in the affected tooth, AA'hich increases as the root becomes enlarged, until pain, either constant or periodical, and of a character more or less severe, is experienced. The most remarkable case of exodontosis on record is related by Mr. Fox. The subject Avas a young lady, who, at the time she came to Mr. F., had suffered so much and so long, that the palpebrse of one eye had been closed for nearly two months; and the secretion of saliva had, for some time, been so copious, that it floAved from her mouth, Avhenever opened. She had tried every remedy science and skill could suggest, Avithout experiencing any permanent benefit, and was only relieved from her suffering by the extraction of every one of her teeth. In the course of the author's practice, he has removed many teeth affected Avith exostosis, but never has met with a case similar to that described by Mr. F. In one instance, he was compelled to extract four sound teeth and nine roots; yet the pain was not at any time severe, but it was constant, and a source of great annoyance to the patient. The following is one among the many cases Avhich have fallen under his observation : Mr. S., of Baltimore, in the fall of 1845, called upon us for advice. Having for some time suffered pain in the first left superior bicuspid, he had applied tAATo years before to a dentist for the purpose of having the tooth removed. In the operation, the root, about three-sixteenths of an inch from its extremity, was fractured and left in the socket. In consequence of this, the gnaAving pain Avith Avhich he had for a long time before been troubled, continued, and at the expiration of twelve months, the gum over the remaining portion of the root became very much swollen, puffing out the lip to the size of half a hen's egg. The tumor, after a few days, was opened, and a large quantity of dark- colored, fetid, purulent matter was discharged, Avhich, for a short time, gave considerable relief. The tumor, howe\Ter, was re-formed, and opened some four or five times in as many months. At this time his gum was swollen, and the upper lip puffed out in the manner just de- 260 EXOSTOSIS OF THE TEETH. scribed. On opening the tumor, about three table-spoonfuls of black matter, resembling thin tar, escaped. We then found, upon examina- tion, that the outer wall of the antrum, immediately over the remain- ing portion of the root of the first bicuspid, Avas destroyed, and there was an opening through it large enough to admit the forefinger. Be- lieving that the extremity of the root left in the socket was the cause of the disease, we immediately proceeded to extract it, Avhich we suc- ceeded in doing after removing the outer wall of the alveolus. The root was found, on removal, to be enlarged by exostosis to the size of a very large pea. The operation proved perfectly successful, the se- cretion of purulent matter soon ceased, and in a feAV weeks he Avas completely relieved from the troublesome affection under Avhich he had so long labored. Several years ago, Prof. Gorgas, while demonstrating practical anatomy in the Baltimore College of Dental Surgery, discovered all the teeth in the mouth of one of the subjects (a negro girl aged about twenty-five years) to be in an exostosed condition. On the roots of one of the superior molar teeth the deposit of osseous matter measured three-fourths of an inch in diameter; this tooth, with the portion of process forming its cavity, is noAV in the museum of the college. CAUSES. The primary cause of this disease does not appear to be well un- derstood. Most Avriters concur in attributing the proximate cause to irritation of the periosteum of the root; but this is not, as some sup- pose, necessarily dependent upon any morbid condition of the crown itself, for it often attacks teeth that are perfectly sound. It seems rather to be attributable to some peculiar constitutional diathesis. TREATMENT. The disease having established itself does not admit of cure, and when it has progressed so far as to be productive of pain and incon- venience to the patient, the loss of the affected teeth becomes inevitable. When the enlargement is very considerable and confined to the ex- tremity of the root, and has not induced a correspondent enlargement of the alveolus around the neck of the tooth, the extraction of the affected organ is often attended with difficulty, and can only be accom- plished by removing a portion of the socket, or fracturing it. Some are of the opinion, however, that the deposit of osseous matter may be arrested and absorption excited so as to make room for that already deposited by the administration of iodide of potassium DENUDING OF THE TEETH. 261 CHAPTER XVIII. DENUDING OF THE TEETH. THIS is one of the most remarkable affections to Avhich the teeth are liable. It consists in the gradual wasting of the enamel on the labial surfaces, attacking first the central incisors, then the laterals, afterward the cuspids and bicuspids, extending sometimes to the first and second molars. It usually forms a continuous- horizontal groove, as regularly and smoothly constructed as if it had been made with a file. (See Fig. 54.) After it has removed the enamel, it commits its ravages Fig. 54. Fig. 55. upon the subjacent dentine, sometimes penetrating to the pulp-cavity. It rarely changes the color of the enamel, but the dentine, after it becomes exposed, assumes first alight, and afterward a dark-brown color; retain- ing, howcATer, a smooth and polished surface. This destructive process does not always commence at merely one point on the labial surface of the central incisors, as just described; it sometimes attacks several points simultaneously. (See Fig. 55.) As it spreads, these unite, and ultimately a deep excavation is formed, with walls so smooth and highly polished that the tooth presents the appearance of having been scooped out Avith a broad, square, or round-pointed instrument. The progress of the affection is exceedingly variable. It is some- times so rapid that the dentine becomes exposed Avithin two or three years from the commencement of the disease; at other times its effect upon the enamel is scarcely perceptible for the first six or eight years after it makes its appearance. In the case of a lady whose teeth were thus affected, the denuding process did not perforate the enamel for nearly twenty years. The dentine, after it is denuded of enamel, is generally quite sensitive, and very susceptible to heat and cold. CAUSES. The cause of this singular affection has never been satisfactorily explained. It was first noticed by Mr. Hunter, who calls it decay by denudation, and supposes that it is a disease inherent in the tooth 262 DENUDING OF THE TEETH. itself, and not dependent on circumstances in after life; for the reason that it attacks certain teeth rather than others, and is often confined to a particular tooth. Mr. Bell thinks Mr. Hunter has confounded this affection with an- other, similar in its appearance, but arising from a wholly different cause. Mr. Hunter states that he has seen instances where it appeared as if the outer surface of the dentine, Avhich is in contact with the inner surface with the enamel, had first been lost, so that the cohesion between the two had been destroyed ; and as if the enamel had been separated for want of support, for it terminates abruptly. Upon Avhich Mr. Bell remarks : "Mr. Hunter describes very accurately the result of superficial absorption of the bony structure; a circumstance Avhich I have occasionally seen, though more rarely than the present abrasion of the enamel, with Avhich it cannot for a moment be considered as identical. In one case the enamel is gradually and slowly removed by a regular and uniform excavation; in the other, the abruptness and irregularity of the edges show that it had broken away at once, from having lost its subjacent support. The cause of the former is external; in the latter it is Avithin the enamel." Mr. Bell, in attempting to correct one error, has fallen into another, equally great and palpable. He attributes the breaking in of the enamel to absorption of the subjacent dentine, instead of ascribing it to decomposition by chemical agents, Avhich is the true cause. In almost every instance, where the author has found the edges of the enamel in the condition described by Messrs. Hunter and Bell, he has also observed that the surface of the exposed dentine was decayed. But the breaking in of the enamel is not the affection now under con- sideration. That is the result of caries of the subjacent dentine; this, a sort of spontaneous abrasion. Mr. Bell is unfortunate, also, in the suggestions which he throws out in regard to the cause of the disease. " Whatever may be the cause — and at present I confess myself at a loss to explain it, —the horizontal direction in which it proceeds may, I think, be connected with the manner in which the enamel is deposited during its formation ; for it will be recollected that it first covers the apex of the tooth, and gra- dually invests the crown by successive circular depositions; it is, there- fore, not improbable that, from some temporary cause, acting during its deposition, certain circular portions may be more liable to mechan- ical abrasion, or other injury, than the rest." This conjecture, though it may seem someAvhat plausible, is far from satisfactory. If, as he supposes, certain circular portions of the enamel are less perfectly formed than others, and consequently rendered more liable to the disease, it would not be wholly confined to the anterior DENUDING OF THE TEETH. 263 surface of the tooth, but would extend entirely around it, and as soon as these imperfectly formed circular portions were destroyed, its ravages would cease. Mr. Fox frankly acknowledges his inability to assign any cause for this affection; but conjectures that it is dependent upon some solvent quality of the saliva. Were this supposition correct, every part of the tooth would be alike subject to its attack. Other writers suppose it is occasioned by the friction of the lips. But this hypothesis is destitute of the least semblance of plausibility; for the narrowness and depth of the grooves are sometimes such as to preclude the possibility of the contact of the lips with their surfaces. Some eminent practitioners, again, attribute it to the use of tooth- brushes. That this may increase the size of the horizontal groove is more than probable ; that it may even in some cases determine the commencement of the groove, is just possible. But no conceivable action of the brush could be an inciting cause of that form of the dis- ease shown in Fig. 55. The true explanation must meet both cases. Hence the author has been led to adopt the opinion that the loss of substance which characterizes the affection is produced by the action of acidulated buccal mucus. In every other part of the mouth this fluid is mixed with saliva, and the acid it contains so much diluted as to prevent it from acting on other portions of the teeth. Dr. E. Parmly reports a case in which the natural teeth, set upon an artificial piece, Avere attacked in the same manner. TREATMENT. As a preventive, Mr. Fox recommends the avoidance of whatever tends to produce it; but, unfortunately, he leaves his readers entirely in the dark upon this subject. In advanced stages of the affection, the author has often succeeded in arresting the progress by widening the groove at the bottom, and afterwards filling it with gold. This, in the majority of cases, will prove successful. The patient should be cau- tioned against the use of stiff-bristled tooth-brushes, and should not, in using any kind, make too much movement across the front teeth, but rather up and down. Should the groove become discolored, it Avill be proper to use occasionally a little fine rotten-stone or prepared chalk on a small stick of some hard wood. 264 CHEMICAL ABRASION OF THE TEETH. CHAPTER XIX. CHEMICAL ABRASION OF THE TEETH. THE chemical abrasion of the cutting edges of the front teeth is an affection of very rare occurrence. It commences on the central incisors, proceeding thence to the laterals, the cuspids, and sometimes, though very rarely, to the first bicuspids. Teeth thus affected have, when the jaws are closed, a truncated appearance ; the upper and lower teeth do not come together, and they are rather more than or- dinarily susceptible to the action of acids, or of heat and cold. In other respects, little or no inconvenience is experienced until the crowns of the affected teeth are nearly destroyed. Its progress, as in the case of abrasion of the labial surfaces, is exceedingly variable. It sometimes destroys half or two-thirds of the crowns of the central incisors in two or three years; at other times seven or eight years are required to produce the same effect. In one case which came under our own observation, the abrasion had extended to the bicuspids, and the central incisors of both jaws were so much wasted, that on closing the mouth they did not come together by nearly three-eighths of an inch; yet two years only had elapsed since its commencement. In another case, where it had been going on for seven years, it had not extended to the cuspids, and the space between the upper and lower incisors did not exceed an eighth of an inch. The subjects of these two were gen- tlemen,— the first aged about twen- ty-eight, and the other twenty-one. Mr. Bell gives an interesting case (Fig. 56) of a gentleman whose teeth Avere thus affected : " About fourteen months since (1831), this gentleman perceived that the edges of the incisors, both above and below, had become slightly worn down, and, as it were, truncated, so that they could no longer be placed in contact Avith each other. This continued to increase and extend to the lateral incisors, and, afterward, successively to the cuspids and bicuspids. There has been no pain, and only a trifling degree of un- easiness, on taking acids, or any very hot or cold fluids, into the mouth. When I first saw these teeth, they had exactly the appearance of hav- ing been most accurately filed down at the edges, and then perfectly CHEMICAL ABRASION OF THE TEETH. 265 and beautifully polished; and it has noAv extended so far that when the mouth is closed, the anterior edges of the incisors of the upper and lower jaws are nearly a quarter of an inch asunder. The cavities of those of the upper jaAV must have been exposed, but for a very curious and beautiful provision; they have become gradually filled by a de- posit of new bony matter, perfectly solid and hard, but so transparent that nothing but examination by actual contact could convince an observer that they were actually closed. This appearance is exceed- ingly remarkable, and exactly resembles the transparent layers which are seen in agatose pebbles, surrounded by a more opaque mass. Ths surface is uniform, even, and highly polished, and continues, without the least break, from one tooth to another. It extends at present to the bicuspids, is perfectly equal on both sides, and when the molars are closed, the opening, by this loss of substance in front, is observed to be widest in the centre, diminishing gradually and equally on both sides to the last bicuspids." CAUSES. With regard to the cause of this most extraordinary affection, Mr. Bell, referring to the case Avhich he describes, says, he is "wholly at a loss to offer even a conjecture. It cannot have been produced by the friction of mastication, for these teeth have never been in contact since the commencement of the affection ; nor does it arise from any appa- rent mechanical cause, for nothing is employed to clean the teeth ex- cept a soft brush. Absorption will equally fail to account for it, for not only would this cause operate, as it always does, irregularly ; but we find that, instead of these teeth being the subjects of absorption, a new deposition of bony matter is, in fact, going on, to fill the pulp- cavities Avhich would otherwise be exposed." Mr. Bell is correct in supposing that it is not the result either of mechanical action or absorption. If, then, neither of these agencies are concerned in its production, it must be the result of some chemical action ; though not of the salivary fluids of the mouth, for, if so, every part of the exterior surfaces of the teeth would be acted on alike. This affection, as well as the one last noticed, the author is disposed to attrib- ute to the action of acidulated mucus. The anterior surfaces of the upper front teeth not being so frequently Avashed by the saliva, the mucous secretions of the upper lip are often permitted to remain on these portions of the teeth for a considerable length of time; and to the presence of these, when in an acidulated condition, Ave believe the denuding process to be attributable; while the abrasion of the cutting edges of the incisors and cuspids is caused by an acid mucus, secreted from the mucous follicles of the end of the tongue, which is brought 266 MECHANICAL ABRASION OF THE TEETH. in contact with the cutting extremities of the front teeth almost con- stantly. Dr. Nuhn, a German physician, describes a gland which he has recently discovered in the interior of the tip of the tongue. It is repre- sented as having a number of ducts opening through the mucous mem- brane over it. It is thought to be a mucous gland, and it may be that this gland, in peculiar diatheses, secretes the acidulated mucus which may cause the affection under consideration. Be this hypothesis correct or not, it is evidently the result of the action of a chemical agent; and that this is furnished by the end of the tongue is rendered more than probable from the fact that it is brought in contact with the cutting edges of the teeth almost every time the mouth is opened. TREATMENT. If the tendency to an acidulated condition of the mucous secretions of the mouth could be overcome or counteracted, the progress of this affection of the teeth, perhaps, might be arrested. But the permanent cure of an obscure abnormal condition of any secretion is a tedious, difficult, and often impossible thing. It may require hygienic and con- stitutional treatment, such as comes more within the province of the family physician than of the dentist. But we know of no treatment that will control or arrest this singular disease. CHAPTER XX. MECHANICAL ABRASION OF THE TEETH. WERE it true, as declared by Richerand, that the loss of the enamel occasioned by friction is repaired by a new growth, it would never suffer permanent loss from mechanical abrasion. But enamel and den- tine, once formed, pass beyond the sphere of that reparative power found in other bony tissues Avhere red blood circulates freely. New enamel is therefore never formed after the eruption of the tooth; and new dentine only upon the surface of the lining membrane, which is exceedingly vascular. The teeth rarely suffer loss of substance from friction Avhen the inci- sors of the upper jaAV shut in front of those of the lower. It is only when the former fall directly upon the latter, that mechanical abrasion of the cutting edges can take place, and when this happens, they some- times suffer great loss of substance. The crowns of these teeth are INJURIES FROM MECHANICAL VIOLENCE. 2G7 occasionally Avorn entirely off, Avhile those of the molars and bicuspids are, comparatively, little affected. The lateral motions of the jaw, being in these cases unrestricted —and this motion being of course greater at the anterior than at the posterior part of the mouth — it necessarily happens that the front teeth suffer the most abrasion. Sometimes all the teeth are Avorn off alike ; at other times, owing to the peculiar manner in Avhich the jaws come together, the abrasion is confined to a few. Mr. Bell believes that certain kinds of diet tend, more than others, to produce abrasion of teeth: in proof of Avhich he tells us that sailors, who, the greater portion of their lives, live on hard biscuits, have only a small part of the croAvns of their teeth remaining. But the antago- nism of the teeth has much more to do with it than the nature of the food ; though of course, when they do strike in such a way as to Avear the cutting surfaces, very hard or gritty articles of food Avould make the abrasion more rapid. When the front teeth of the lower jaw strike against the palatine surface of those of the upper, the latter are sometimes worn away more than three-fourths, and in some instances entirely up to the gums. We have seen the teeth of some individuals so much abraded, in this way, that little of the crown remained, except the enamel on the anterior surface. The wearing away of the crowns of the teeth would expose the lining membrane, were it not that Nature, in anticipation of the event, sets up an action by Avhich the pulps are transformed into a substance called osteo-dentine, which is analogous in structure to cementum. By this beautiful operation of the economy, the painful consequences that would otherwise result are wholly prevented. CHAPTER XXI. FRACTURES AND OTHER INJURIES OF THE TEETH FROM MECHANICAL VIOLENCE. THE injuries to which teeth are subject from mechanical violence are so variable in their character and results as to render a detailed description impossible. The same amount of violence inflicted upon a tooth does not always produce the same effect. The nature and extent of the injury will depend as much upon the physical con- dition of the teeth, the state of the constitutional health, and the sus- 268 INJURIES FROM MECHANICAL VIOLENCE. ceptibility of the body to morbid impressions, as upon the violence of the blow. Thus, a blow sufficiently severe to loosen a tooth might not, in one case, be productive of any permanent bad consequences; Avhile in another, it might cause the death of the organ and inflammation of the adjacent parts, as Avell as necrosis of the alveolus. A tooth of compact texture, and in a healthy mouth, may be deprived of a portion of its substance without any serious injury; but a similar loss of substance in a tooth not so dense in structure Avould be likely to produce inflammation and suppuration of the lining membrane, and possibly of the alveolo-dental periosteum. Hence, in order to form a correct opinion of the result of injuries of this sort, we must take into consideration not only the character of the tooth upon which the blow has been inflicted, but also the state of the mouth and the health of the individual. If the tooth is not loosened in its socket, any injury resulting from a loss of a small portion of the enamel, or even of the dentine, may be prevented by smoothing the fractured surface with a file, that the juices of the mouth and particles of extraneous matter may not be retained in contact Avith it. But if the tooth is loosened, and inflam- mation of the investing membrane has supervened, leeches should be applied to the gums, and the mouth washed several times a day with some astringent lotion, until the inflammation subsides. For more detailed treatment, the reader is referred to the chapter on perios- titis. When a tooth has been displaced from its socket by a bloAV, and its vascular connection Avith the general system destroyed, necrosis must, as an almost necessary consequence, be the result. An imperfect union between the tooth and alveolus may sometimes be re-established by the effusion of coagulable lymph, and the formation of an imperfectly organized membrane; but the tooth will ever after, from the slightest cold, or derangement of the digestive organs, be liable to become sore to the touch, and in most cases will ultimately assume a muddy brown, unhealthy appearance. The author has, on several occasions, replaced teeth that had been knocked from their sockets; and in some instances the operation was attended with success. The subject in one case Avas a healthy boy, of about thirteen years of age, who, while playing bandy, received a blow from the club of one of his playmates, which knocked the left central incisor of the upper jaw entirely out of its socket. He saw the boy about fifteen minutes after the accident. The alveolus was filled with coagulated blood. This he sponged out, and, after having bathed the tooth in tepid water, carefully and accurately replaced it in its socket, and secured it there by silk ligatures attached to the adjacent INJURIES FROM MECHANICAL VIOLENCE. 269 teeth. On the following day the gums around the tooth Avere con- siderably inflamed, to reduce which inflammation he directed an application of three leeches and the frequent use of diluted tincture of myrrh as a Avash for the mouth. At the expiration of four weeks the tooth became firmly fixed in its socket, but from the efiusion of coagulable lymph, the alveolar membrane was thickened, and the tooth, in consequence, protruded somewhat. A slight soreness, on taking cold, has ever since been experienced. Dr. Noyes, of Baltimore, mentioned to the author a case of a some- what similar character. The subject was a boy about ten years of age. One of his front teeth was forced from its socket by a fall. It was replaced shortly after, and in a few weeks became firm in its alveolus. Mr. Bell also mentions a case attended with a like result. The alveolar processes and jaw-bones are sometimes seriously in- jured by mechanical violence. In 1843, the author Avas requested by the late Dr. Baker, of Baltimore, to visit, Avith him, a lady avIio, by the upsetting of a stage, had her face severely bruised and lacerated. All that portion of the lower jaAV Avhich contained the six anterior teeth was splintered off, and was only retained in the mouth by the gums and integuments with Avhich it was connected. The wounds of her face having been properly dressed, the detached portion of the jaw Avas carefully adjusted and secured by a ligature passed around the front teeth and first molars, and by a bandage on the outside, around the chin and back part of the head. Her mouth was Avashed five or six times a day Avith diluted tincture of myrrh. The third day after the accident, Dr. Baker directed the loss of twelve ounces of blood; and, in five or six weeks, Avith no other treatment than the dressing of the wounds, she perfectly recovered. It often happens that the crown of a tooth is broken off at the neck. We have knoAvn the croAvns of four, and in one case of thirteen, teeth to be fractured by a single blow. The subject of the last case was a fireman, who, in 1835, received an accidental blow on his mouth from the head of an axe, which broke off the crowns of all the upper and loAver incisors, two cuspids, and three of the bicuspids of the inferior maxilla. The subject in the other case AA'as a boy about twelve years of age, Avho, from a similar accident, occasioned by running up sud- denly behind a man who Avas chopping wood, had the crowns of his upper incisors broken off. In both of these cases the inflammation which supervened Avas so great as to render the removal of the roots necessary. The crowns, roots, and alveolar processes are sometimes ground to pieces, or the teeth driven into the very substance of the jaAV. Mr. Bell says he once found a central incisor so completely 270 CARIES OF THE TEETH. forced into the bone, that he thought it to be the remains of a root; but, on removing it, found it to be an entire tooth. WThen the croAvn of a tooth has been broken off by a bloAV, and de- structive inflammation results, the root should be extracted. We have sometimes engrafted an artificial crown on a root after the natu- ral crowm has been destroyed by mechanical A'iolence; but it is very necessary that the inflammation should be entirely subdued previous to the operation of pivoting. If the tooth is to be replaced with an artificial substitute attached to a plate, the root should be first ex- tracted. In some cases, however, the root may be filled and be per- mitted to remain; but the practice is usually a bad one. CHAPTER XXII. CARIES OF THE TEETH. THE doctrine, as promulgated by Fox, and, subsequently, advocated by Bell, and other European writers, that the diseases of the teeth are the same as those which attack other osseous structures of the body, is noAV almost universally conceded to be incorrect. With the exception of exostosis and necrosis, the pathological condition of these organs do not bear the slightest analogy to those of other bones. They are not produced by the same causes, nor can they be cured by the same remedies. In the treatment of diseases of the teeth we rely mainly upon art; in diseases of other osseous tissues the resources principally to be relied on are found in the recuperative poAvers of the economy. This differ- ence is clearly seen between caries in the teeth and in the bones. Nature alone can repair the ravages of the one, art alone of the other. Exostosis, which is a disease common to bone and teeth, is found only in the cementum, which is the connecting link between dentine and osseous tissue; Avhilst diseases of the dentine and enamel form a dis- tinct class, requiring treatment altogether peculiar to themselves. The teeth are more liable to be attacked by caries than by any other disease, and this will now claim our attention. Caries of a tooth is the chemical decomposition of the earthy salts of the affected part, sometimes, but not always, accompanied by disor- ganization of the animal framework of this portion of the organ. There is no affection to which these organs are liable more frequent in its occurrence, or fatal in its tendency, than this. It is often so insidi- ous in its attacks, and rapid in its progress, that every tooth in the CARIES OF THE TEETH. 271 mouth is involved in irreparable ruin before even its existence is sus- pected. Its presence is usually first indicated by an opaque or dark spot on the enamel; and, if this be removed, the subjacent dentine will exhibit a black, dark-broAvn, or whitish appearance. It usually commences on the outer surface of the dentine of the crown, beneath the enamel, at some point where it is imperfect, or has been fractured or otherwise injured; from thence it proceeds tOAvard the centre of the tooth, in- creasing in circumference until it reaches the pulp-cavity. If the diseased part is of a soft and humid character, the enamel, after a time, usually breaks in, disclosing the ravages the disease has made on the subjacent dentine. But this does not ahvays happen ; the form of the tooth sometimes remains nearly perfect until its Avhole interior structure is destroyed. No portion of the crown or neck of a tooth is exempt from this disease; yet some parts are more liable to be first attacked than others; as, for example, the depressions in the grinding surfaces of the molars and bicuspids, the approximal surfaces of all the teeth, the posterior. or palatine surfaces of the lateral incisors, and, in short, wherever an imperfection of the enamel exists. The enamel is much harder than the dentine, and is by far less easily acted on by the causes that produce caries. It is sometimes, hoAvever, the first to be attacked, and Avhen this happens, the disease develops itself more frequently on the labial, or buccal surface, near the gum, than in any other locality; often commencing at a single point, and at other times at a number of points. When the enamel is first attacked, it is usually called erosion ; but as this tissue does not contain so much animal matter as the subjacent dentine, the diseased part is often washed away by the saliva of the mouth ; Avhile in the dentinal part of the tooth, it, in most instances, remains, and may be removed in distinct laminae, after the earthy salts haA^e been decomposed. In very hard teeth, the decayed part is of a firmer consistence, and of a darker color, than in soft teeth. Sometimes it is black ; at other times of a dark or light broAvn ; and at other times, again, it is nearly white. As a general rule, the softer the tooth, the lighter, softer, and more humid the caries. The color of the decayed part, hoAvever, may be, and doubtless is, in some cases, influenced by other circumstances ; perhaps by some peculiar modification of the agents concerned in the production of the disease. The disease, then, not being the result of any vital action, the appli- cability of the term caries may be questioned ; but, as it has been very generally sanctioned, and as we know of no better name, Ave shall con- tinue its use. Mr. Bell has substituted the term gangrene, under the 272 CARIES OF THE TEETH. belief that it conveys a more correct idea of the true nature of the affection. The applicability of a term, almost synonymous with this, is also suggested by Mr. Hunter: in speaking of the affection, he says, that it "appears to deserve the name of mortification." Mr. Fox speaks of the decay of the teeth as a disorder Avhich terminates in mortifica- tion ; but he designates it by the name of caries. We prefer this term, inasmuch as that of gangrene, or mortification, may be applied to an- other condition of the teeth — necrosis — with as much propriety as the one now under consideration. Moreover, the term gangrene, or morti- fication, is commonly used to signify the death of a soft part, and not a diseased condition of bony tissue. Surgical writers usually regard gangrene in soft tissues as analogous to necrosis in osseous tissues; and ulceration in the first analogous to caries in the last. But necrosis and caries in the teeth differ in causes, symptoms, sequelae and treat- ment, from affections of the same name in other bones, in consequence of the great difference in their structure, function, and mode of connec- tion with the adjacent tissues. Commencing externally beneath the enamel, the disease proceeds, as before stated, toward the centre of the tooth, destroying layer after layer, until it reaches the lining membrane, leaving each outer stratum softer, and of a darker color, than the subjacent one. The terms deep-seated, superficial, external and internal, simple and complicated, have been applied to the disease. These distinctions are unnecessary, since they only designate different stages of the same affection. By complicated decay is meant caries which has penetrated to the pulp-cavity of the tooth, accompanied by inflammation1 and suppuration of the lining membrane, and the death of the organ. The lining membrane, however, is not ahvays inflamed by exposure, nor is inflammation invariably folloAAred by suppuration. The roots of the teeth frequently remain firm in their sockets for years after the crowns and necks have been destroyed, shoAving that they are less liable to decay than the croAvns; but nature, after the destruction of the last, as if conscious that the former are of no further use, exerts herself to expel them from the system, Avhich is effected by the gradual wasting and filling up of their sockets. After this opera- tion of the economy has been accomplished, they are frequently re- tained in the mouth for months, and even for years, by their periosteal connection with the gums. This effort of nature is confined more to the back than to the front teeth ; it often happens that the last remain, after the destruction of their crowns, for many years, and sometimes without much apparent injury to the parts within which they are con- tained. CARIES OF THE TEETH. 273 DIFFERENCES IN THE LIABILITY OF DIFFERENT TEETH TO DECAY. Having explained at some length, in a preceding part of this Avork, the manner in Avhich the physical condition of the teeth is influenced, it will not now be necessary to dwell upon this portion of the subject. It will only be requisite to state, therefore, that teeth Avhich are Avell formed, well arranged, and of a firm texture, seldom decay, and Avhen they are .attacked, the progress of the disease is not rapid ; Avhereas, those that are imperfect in their formation, and of a soft texture, are more susceptible to the action of the causes Avhich produce it; and when assailed, if the progress of the affection is not arrested by art, they usually fall speedy victims to its ravages. Just in proportion as the dentinal structure of the.teeth is hard or soft, the shape of the organs perfect or imperfect, their arrangement regular or irregular, is their liability to caries diminished or increased. The density, shape, and arrangement of the teeth are influenced by the state of the general health, and that of the mouth, at the time of their dentinification. If, at this period, all the functions of the body are healthily performed, these organs wil 1 be compact in their struc- ture, perfect in their shape, and usually regular in their arrangement. That the teeth should be thus influenced will not appear strange, Avhen we consider, as Richerand remarks, " that there exists amongst all the parts of the living body intimate relations, all of which correspond to each other, and carry on a reciprocal intercourse of sensations and affections. Hence, if there is a morbid action in one part, other parts sympathize Avith it, rallying, as if sensible of the mutual dependence existing betAveen them, all their energies to rescue their neighbor from the poAver of disease." Increased action in one portion of the system is generally followed by diminished action in some other part; thus, for example, gastritis may be produced by constipation of the boAvels; puerperal fever, by diminished action in the heart, with an increased action in the uterus, etc. Hence, Ave may conclude, that if the body, at an early age, be morbidly excited, its functions will be languidly performed — the pro- cess of assimilation checked — the regular and healthy supply of earthy matter in the benes interrupted — and, consequently, that the teeth which are then formed will be defective. Other parts of the body, in which constant ch.uiges are going on, if thus affected at these early periods, may afterward recover their healthful vigor ; but if the teeth are badly formed, they must ever, because of their low degree of vascularity, continue so; hence they will be more liable to decay than when den- tinified under other and more favorable circumstances. Capillary bloodvessels form a large part of every organ, the charac- 18 274 CARIES OF THE TEETH. teristic tissue of each being strictly extra-vascular (literally, outside of the vessels). Where the bloodvessels are most abundant, as in the ner- vous and muscular structures, growth and change take place rapidly and constantly; since almost every particle of the extra-vascular or interstitial tissue is in contact Avith the circulating fluid, the function of Avhich is to supply material for growth and carry off waste matter. Hence such organs have great recuperative power, and are modified by the varying conditions of the body. But the dentine and enamel of the teeth are vascular only during the period of development. These structures, once formed, pass beyond the reach of the capilla- ries, except the layer of dentine in contact Avith the dental pulp, Hence, the dental pulp may deposit neAV bone as a barrier against caries ; but the carious dentine itself is incapable of self-restoration. "That the teeth acquire this disposition," says Mr. Fox, "to decay, from some want of healthy action during their formation, seems to be pro\red by the common observation, that they become decayed in pairs; that is, those which are formed at the same time, being in a similar state of imperfection, have not the power to resist the causes of the disease, and therefore, at nearly about the same period of time exhibit signs of decay; while those Avhich have been formed at another time, when a more healthy action has existed, have remained perfectly sound to the end of life." Most writers are of opinion, that the power of the teeth to resist the various causes of decay is sometimes weakened by a change brought about in their physical condition through the agency of certain remote causes, such as the profuse administration of mercury, the existence of fevers, and all severe constitutional disorders. Mr. Fox says: "That he has had occasion to observe, that great changes take place in the economy of the teeth in consequence of con- tinued fever ; and that the decay of the teeth is often the consequence of certain states of the constitution." Mr. Bell remarks: "That amongst the remote causes (of decay) are those which produce a deleterious change in the constitution of the teeth subsequent to their formation ; one of the most extensive, in its effects, is the use of mercury. To the profuse administration of this remedy in tropical diseases, Ave may, Ave think, in a great measure, attribute the injury which a residence in hot climates so frequently inflicts on the teeth." Severe constitutional disorders, and the administration of certain kinds of medicine, do not, as Messrs. Fox and Bell suppose, act directly on the teeth, by altering their physical condition, and thus rendering them more susceptible to the action of corrosive agents; but they are CARIES OF THE TEETH. 275 indirectly affected in proportion as the secretions of the mouth are vitiated and their corrosive properties increased. The folloAving considerations establish, to our mind, the truth of what Ave have just stated. Artificial teeth of bone or ivory, Avhich can undergo no such changes as those mentioned by Mr. Bell, decay more rapidly after the profuse administration of medicine, or during the existence of any disease that tends to vitiate the secretions of the mouth, than at other times. Furthermore, teeth of so dense a texture as to be capable of resisting the action of the acidulated buccal fluids are not affected by constitutional disease; yet they are just as liable as those of a spongy texture, to any structural disease communicated from the general system. The following is the result of our oAvn observations: the gums and alveolar processes are sometimes destroyed by the use of mercury, so that all the teeth loosen and drop out, without being affected by caries. The teeth of persons, in Avhom a mercurial diathesis has been a long time kept up, or who have been for years suffering from dyspepsia, phthisis, fevers, or other severe constitutional disorders, often continue perfectly sound; while other teeth, under similar circumstances, fre- quently decay. Now, all this goes to prove, not that changes are effected in the structural condition of the teeth, Avhereby their predisposition to decay is increased, but that there are differences in the capabilities of different teeth to resist the action of the secretions of the mouth, made acrid by the affections just enumerated. The author is well aAvare that he differs from some Avriters on this point, as Avell as from received popular opinion. The views Avhich ho has here presented, are not the result of mere closet reflections, but of long and attentive observation. He has noted the effects of mercury, and of other medicines, as Avell as of constitutional diseases of the severest and most protracted kinds, and he has ahvays observed that — occurring after the development of the teeth — it Avas only as they impaired the healthy qualities of the fluids of the mouth that they affected these organs. In fact, their density, their exposed situation, their functions, all would seem to indicate that such changes as take place in other parts of the body are not only unnecessary, but many of them are impossible, and designedly so, that they may more fully answer their purpose. Dr. Good says " that caries of the teeth does not appear to be a dis- ease of any particular age or temperament, or state of health." It is true it is not a disease of any particular state of health, farther than that certain constitutional affections exert a deleterious influence upon the secretions of the mouth, and thus become indirect causes of decay of these organs. That it is not a disease of any particular age seems 276 CARIES OF THE TEETH. to-contradict common experience, for it comparatively seldom happens that caries appears after the age of forty. The reason of which is obvious. Teeth of a loose texture, or othenvise imperfect, cannot re- sist the action of the causes of decay, to Avhich all teeth are, up to this period of life, more or less exposed; while those Avhich from their greater density remain unaffected thus long, are generally enabled, by the increased solidity they gradually acquire, to resist them through life. Teeth sometimes, though rarely, decay at fifty, or even at a later period ; but caries of the teeth, generally, may be said to be confined to youth and middle age. The formation, arrangement, and physical condition of the teeth are sometimes influenced by hereditary diathesis, affecting the parts Concerned in their production, or the general system. That a morbid condition of the system, on the part of either parent, often predisposes their progeny to like affections, is an axiom fully recognized in pathol- ogy, and a fact of which we have many fearful proofs. Mr. Bell, in treating of what he calls the hereditary predisposition of the teeth to decay, remarks: " That it often happens that this ten- dency exists in either the whole or a great part of a family of children where one of the parents had been similarly affected; and this is true to so great an extent that we have commonly seen the same tooth, and even the same part of a toothr affected in several individuals of the family, and> at about the same age. In other instances, Avhere there are many children, amongst whom there exists a distinct division into two portions, some resembling the father, and some the mother, in features and constitution, we observe corresponding differences in the teeth, both as it regards their form and texture and their tendency to decay." That there is an hereditary tendency in the teeth to decay, cannot, we think, be denied. But we believe it to be the result of the trans- mission of a similarity of action in the parts concerned in the produc- tion of these organs; so that the teeth of the child are, in form and structure, like those of the parent whom it most resembles, and from whom it has inherited the diathesis. The teeth of the child, if shaped like those of the parent, possessing a like degree of density, and simi- larly arranged, are equally liable to disease; when exposed to the action of the same causes, they are affected in like manner, and, usually, at about the same period of life. Such being the fact, is it unreason- able to conclude that judicious early attention may so influence the formation and arrangement of the teeth that their liability to disease may be diminished ? Whilst denying the direct action of medicine and sickness upon the dental tissues, except through the agency of the buccal secretions, Ave admit their poAverful influence ; first, through CARIES OF THE TEETH. 277 hereditary transmission of an impaired constitution ; secondly, by their action upon the process of development, if given while the teeth are being formed. It is, then, to the differences in the physical condition and manner of arrangement of these organs — whether in different individuals or in the same mouth —that the differences in their liability to decay is attributable. Dr. John Allen remarks: " The nutritious substances in the food that we take are intended to build up all parts of the system — the hard tissues as Avell as the soft tissues. Of the food intended to build up these organisms, certain portions make bone and teeth. Noav the particles of matter are deposited atom by atom, and the system is gradually built up. When Ave take food into the system, it is con- verted into blood. This blood is conveyed through all parts in little corpuscles, which are freighted with the proper constituents to sustain and build up these organisms. These little corpuscles convey such constituents as are necessary for the production of bone, teeth, flesh, and the fat, and these various substances are deposited just where they should be. Noav it is essentially necessary that we have these little vesicles freighted Avith the proper constituents, and duly freighted. Hoav shall we know this ? By taking the food just in the proportion that it is provided for us by our Creator, and as it comes from nature's laboratory. " Now Ave take this ground from the fact that, as a nation, we have worse teeth than any other on the earth Noav why is this? Simply because Ave change the proportions of these various constituents, that our Creator has provided for us, by separating away what has been put there for the building up of the hard tissues. "To prove this, let us look to other nations. They that do not change the proportions of the various constituents that enter into their bodies do not have decayed teeth. " There is a constant change going on, and particles of matter are deposited atom by atom, and the system kept fully charged Avith the mineral elements of Avhich these structures are built up. When yon look at nations that do not change the proportions, you see no decayed teeth, and the history of these nations proves that their teeth are sound and beautiful to old age. What is the condition in our country? We do change these proportions. We do ignore the mineral elements pro- vided for us, and Ave do have decayed teeth. We find that there are over twenty millions of teeth swept from our population every year. We do not take the material into our system that carries back, atom by atom, and keeps the hard tissues built up until the old particles pass aAvay. The old particles pass aAvay after they have served their purpose, and neAV ones then take their places. 278 CARIES OF THE TEETH. "It is estimated that every child uses half a barrel of flour every year; and it is estimated that there are forty pounds of the bone-forming material throAvu out from every barrel that we use. The child takes its food on fine flour, and is deprived of twenty pounds in a year of this mineral element, which should be taken into the system in order to make those hard, flinty substances that our Creator intended. Now, by the time that child is tAventy years of age, it has been deprived of four hundred pounds of the elements Avhich should have been taken into the system, and would have kept it charged sufficiently to have preserved these substances hard and flinty, as they should be. "We sweep from our American population over twenty millions of keeth every year, and this should prove the theory that our tissues do undergo a change, and that, particle by particle, they pass aAvay. As it is noAV, the teeth are becoming Avorse and Avorse every year; and not only this, but it becomes hereditary, and is transmitted from parent to child." CAUSES OF CARIES. Caries of the teeth has been attributed to a great variety of causes. To notice, in detail, the various opinions advanced by American, Eng- lish, French, and German Avriters upon this subject would be incon- sistent Avith the plan of an elementary treatise like this, and unprofit- able to the reader. Fauchard, Auzebe, Bourdet, Lecluse, Jourdain, and most of the French writers of the eighteenth century on the diseases of the teeth, as well as nearly all of the more modern French authors, though their views Avith regard to the causes of dental caries are exceedingly vague and confused, express the belief that, the disease is, for the most part, the result of the action of chemical agents; such, for example, as vitiated saliva, the putrescent remains of particles of food lodged between the teeth, or in their interstices, acids, and a corrupted state of the fluids conveyed to these organs for their nourishment. They also mention certain states of the general health, mechanical injuries, sudden transitions of temperature, etc., as conducing to the disease. A similar explanation, too, of the cause is given by Salmon, the author of a Compendium of Surgery, published in London, in 1644. The existence of an acid in the mouth capable of decomposing the teeth is conclusively proven by Dr. S. K. Mitchell, in a letter addressed by him to T. C. Hope, M.D., of Edinburgh, dated October 10, 1796. The fact may be demonstrated by a very simple experiment, Avhich consists in moistening a piece of litmus paper with the buccal fluids obtained from between the teeth, Avhere they have been retained until they have become vitiated. If this be done, the paper will be turned CARIES OF THE TEETH. 279 red. If, then, these fluids, when in a vitiated condition, are possessed of acid properties, they must necessarily exert a deleterious action upon the teeth, by decomposing and breaking doAvn their calcareous molecules, or, in other words, causing their decay. The acid detected by Dr. Mitchell was the septic (nitrous), but the acetic, lactic, oxalic, muriatic and uric have been detected in the saliva, in certain states of the general health. Donne, avIio has ana- lyzed the fluids of the mouth Avith great care, says, " The saliva, in its normal state, is alkaline, but the secretions of the mucous membrane of the mouth are acid." It is highly probable, therefore, that the acids which have been detected in the first of these fluids, may have been principally derived from the latter. Acidity of the saliva may, hoAvever, occur in certain morbid conditions of the general system. Donne says he has observed it in patients affected Avith gastritis, and in children with aphthae. It is to the action of these acids upon those parts of the teeth against which they are long retained, that caries is principally attributable. The doctrine that the decay of the teeth is the result of the action of external corrosive agents Avas first distinctly promulgated to tho dental profession of the United States, about the year 1821, by Drs. L. S. and Eleazer Parmly. These agents may consist of menstrua, formed by the decomposition of acetous fermentation of the remains of certain aliments lodged in the interstices of the teeth; or of the fluids of the mouth, especially the mucous, in a vitiated or acidulated condition; or of acids administered during sickness, or used as condi- ments. According to the tables of elective affinity, there are but four acids Avhich precede the phosphoric in their affinity for lime : namely, the oxalic, sulphuric, tartaric, and succinic. It may hence be argued that none of the other acids are capable of decomposing the teeth, or of injuring them in any other Avay, but daily observation proves the erroneousness of this conclusion. It has been sIioavii by experiment that all the acids, both vegetable and mineral, act more or less readily upon these organs.* But Ave are disposed to believe that caries of the * The following experiments, made by Dr. A. Westcott, in 1843, assisted by Mr. Dalrymple, were repeated some years later, before the class of the Baltimore Den- tal College: " 1st. Both vegetable and mineral acids act readily upon the bone and enamel of the teeth. " 2d. Alkalies do not act upon the enamel of the teeth ; the caustic potash will readily destroy the bone by uniting with its animal matter. "3d. Salts whose acids have a stronger affinity for the lime of the tooth, than for the basis with which they are combined, are decomposed, the acids acting upon the teeth. " 4th. Vegetable substances have no effect upon the teeth till after fermenta- 280 CARIES OF THE TEETH. teeth results more frequently from the action of some acid contained in the mucous fluids of the mouth, than from that of acid medicines or condiments, or even from such acids as may be generated by the ace- tous fermentation of particles of certain kinds of food lodged between the teeth. The author is of opinion, therefore, that if all the functional operations of the body Avere always healthily performed, caries of the teeth would seldom occur; for, in this case, the alkalinity of the saliva would be sufficient to neutralize the acidity of the mucous fluids of the buccal cavity, as Avell as any other acids generated in the mouth. The foregoing theory of the cause of dental caries explains the rationale of the treatment at present adopted for arresting its progress. By the removal of the decomposed part and filling the cavity Avith an indestructible material, the contact of those agents upon the chemical action of Avhich the disease depends, is prevented, and the further pro- gress of the decay arrested. Among the indirect causes of caries, the following may be enume- tion takes place, but all such as are capable of acetic fermentation, act readily after this acid is formed. "5th. Animal substances, even while in a state of confirmed putrefaction, act very tardily, if at all, upon either the bone or enamel. On examining the teeth subjected to such influence, the twentieth day of the experiment, no visible phe- nomena were presented, except a slight deposit upon the surface of a greenish slimy matter, somewhat resembling the green tartar often found upon teeth in the mouth. "To give a more definite idea of the deleterious agents to which the teeth are exposed, and their consequent liability to be affected by them, we will notice the effect produced by a few of the individual substances which are more or less lia- ble to be brought in contact with the teeth. "Acetic and citric acids so corroded the enamel in forty-eight hours, that much of it was easily removed with the finger-nail. "Acetic acid, or common vinegar, is not only in common use as a condiment, but is formed in the mouth whenever substances liable to fermentation are suf- fered to remain about the teeth for any considerable length of time. "Citric acid, or lemon-juice, though less frequently brought in contact with the teeth, acts upon them still more readily. " Malic acid, or the acid of apples, ill its concentrated state, also acts promptly upon the teeth. " Muriatic, sulphuric, and nitric acids, though largely diluted, soon decompose the teeth : these are in common use as tonics. "Sulphuric and nitric ethers have a similar deleterious effect, as also spirits of nitre: these are common diffusible stimulants in sickness. " Supertartrate of potash destroyed the enamel very readily. This article ia frequently used to form an acidulated beverage. "Raisins so corroded the ennmel in twenty-four hours, that its surface presented the appearance and was of the consistency of chalk. " Sugar had no effect till after acetous acid was formed, but then the effect was the same as from this acid when directly applied." CARIES OF THE TEETH. 281 rated: depositions of tartar upon the teeth; a febrile or irritable state of the body; a mercurial diathesis of the general system; artificial teeth improperly inserted, or made of bad materials; roots of teeth; irregularity in the arrangement of the teeth ; too great pressure of the teeth against each other — in short, everything that is productive of irritation to the alveolo-dental membrane, or to the gums. The doctrine here advocated is one, Avhich, Ave confess, we Avere for a long time umvilling to believe, because it was opposed to all our earlier preconceived notions upon the subject; but long and attentive observation has forced us to acknowledge its truth. PREVENTION OF CARIES. It is an old adage, no less true than trite, that " an ounce of pre- vention is better than a pound of cure," and in the present instance it may be applied Avith its full force. Were more attention paid to the practical instruction thus conveyed, many of the diseases of the teeth might be avoided. Most of the remarks that might be made on this subject have been anticipated; consequently, it will only be necessary to observe, that if the teeth are Avell formed and Avell ar- ranged, all that will be required is to keep them clean; if any irregu- larity occurs, it should be remedied by the means before described. For cleansing the teeth, Avhen they are in a sound condition and free from calcareous deposits, the gums healthy, and the secretions of the mouth normal in character, the regular and frequent use of pure Avater by means of a proper brush and waxed floss silk will, in most cases, be sufficient. But when the enamel is stained and discolored, and the secretions of the mouth inclined to acidity, with a tendency to calcareous deposits, then the employment of a dentifrice is necessary. Dentifrice, from dens, a tooth, and frico, fricare, to rub, is a medicinal preparation, in the form of a powder, for cleansing the teeth. An almost numberless variety of dentifrices are in use, and many of them highly injurious. In the preparation of an agent of this kind, the object should be to obtain a compound pleasant to the taste, altogether free from acids and acrid substances, and soluble or insoluble, accord- ing to the nature of the case in Avhich it is to be used ; one capable of neutralizing and removing acrid and fermenting matters secreted be- tween the teeth, and also allaying irritation. A dentifrice, then, should be anti-acid, and, moreover, a powder; and the more simple the preparation the better. A preparation composed of orris root, pre- pared chalk, and pure Castile or white Windsor soap, to Avhich may be added very finely poAvdered cuttle-fish bone or pumice-stone, for the removal of calcareous matter, Avhen there is a tendency to deposits of this nature, will answer every purpose. When the gums are in a 282 CARIES OF THE TEETH. healthy condition, there is no use for such ingredients in a dentifrice as Peruvian bark or myrrh, and as for liquid dentifrices, they are of very little use, for the object in using the brush is friction, and as these liquid preparations are generally lubricating alkaline substances, they cause the brush to pass so easily over the teeth as to render it almost useless. In many cases, an unhealthy condition of the gums is owing to the irritation produced by local irritants, and their removal is all that is needed to restore them to health. Soap alone Avill not cleanse the teeth, for it prevents friction; and charcoal, notwithstanding its detergent and anti-septic properties, is injurious as a dentifrice, or as an ingredient of one, on account of its insinuating itself under tne free margin of the gum, and causing it to recede from the neck of the tooth, no matter how finely it may be pulverized. Either of the fol- lowing dentifrices may be used : R. Prepared chalk, Powdered orris root, Powdered cinnamon, Sup. carb. of soda, White sugar, Oil of lemon, Oil of rose, 51V- ^iv. 5>SS- Si- gtt. XV jrtt. ij. R. Prepared chalk, . . ^ij. Powdered orris root, . ^ij. Pumice stone, . . . Jj. Ingredients in both prescriptions to be thoroughly pulverized and well mixed. The importance of keeping the teeth clean cannot be too strongly impressed upon the mind of every individual. Proper attention to the cleanliness of these organs contributes more to their health and preservation than is generally supposed. Against caries it is a most powerful prophylactic. "Where the teeth," says Dr. L. S. Parmly, " are kept literally clean, no disease will ever be perceptible. Their structure will equally stand the summer's heat and winter's cold, the changes of climate, the variation of diet, and even the diseases to which the other parts of the body may be subject from constitutional causes." The configuration and arrangement of some teeth is such, hoAvever, as to preclude the possibility of keeping them clean ; but this should not deter any one from using the proper means, for if disease is not Avholly prevented, they will, at least, contribute very greatly to the preservation of the organs. PART THIRD. SURGERY. 2m CHAPTER I. SURGERY. BESIDES the operations of general surgery which are performed upon the mouth in common with other parts of the body, Dental Science gives specific directions for those operations of special surgery demanded in the 1. Treatment of dental caries; 2. Extraction of teeth ; 3. Correction of irregularities in their arrangement. The treatment of caries stands first in order and importance because of the usefulness of the organs to be saved; the universality of the disease; also, the complex and difficult nature of the operations required. The caries may be slight and superficial; or it may be more or less deep-seated; lastly, it may penetrate even to the pulp-cavity. The difficulties of treatment increase in the same order, and in this order they will be taken up. Caries, when superficial, may be arrested by the same means used for deeper caries; but, in a large number of cases, it will require for its removal only the use of files and enamel- ohisels. These instruments are also often used preparatory to the operations necessary for the arrest of deep-seated caries; hence the use of the file and enamel-chisel demands our first consideration. FILING TEETH. There is no operation in dental surgery against which a stronger or more universal prejudice prevails than that of filing the teeth ; yet, when judiciously and skilfully performed, there is no one more bene- ficial or effectual in arresting the progress of caries. Although pro- ductive of much good, it is, in the hands of unskilful operators, a source of incalculable injury. Dr. John Harris says, "Filing the teeth is one of the most important and valuable resources of the dental art; it is one that has stood the test of experience, and is of such acknoAvledged utility, as to constitute of 285 286 SURGERY. itself, in the treatment of superficial caries on the lateral surfaces of the teeth, one of the most valuable operations that can be performed on these organs. And even after caries, in the localities just men- tioned, has progressed so far as to render its removal by this means impracticable or improper, the use of the file, in most cases, is still necessary, in order to the successful employment of other remedial agents. But in either case a failure to accomplish the object for which it is used would only be equivalent to doing nothing at all. "The use of the file, then, may very justly be considered a sine qua non for the removal of superficial caries from the sides of the teeth which come in contact with each other, as can be attested by thou- sands of living Avitnesses; and in preparing the way, in deep-seated caries, for the thorough removal of the disease, and filling, success- fully, the cavity thus formed. "In a paper written by myself, some eleven or twelve years ago, upon this subject, I contended that filing the teeth was not necessarily productive of caries, and my subsequent experience and observations have only tended to confirm the correctness of the opinion Avhich I then advanced, and I cherish the belief that this opinion Avill not, at this time, conflict with the views of the more enlightened of my pro- fessional brethren. "ButAvhen reference is had to the physical peculiarities of the teeth, it Avill at once be perceived that they present a strange departure from the laws that govern and control all other parts of the body; and these organs, Avhen diseased, can only be restored to health and usefulness by art, unaided by the sanitary poAvers of nature. Hence it is, that most of the operations upon them will not, like those in general surgery, admit of mediocrity in their performance. ******** " The fact that the crowns of the teeth are covered Avith enamel, is alone sufficient evidence of its importance and utility in shielding and protecting the bony structure Avhich it envelops from mechanical and morbid influences ; so that it would seem that its removal or loss Avould necessarily expose the organs to certain destruction. But we have satisfactory evidence that teeth, after having suffered the loss of large portions of the enamel, have been restored to health, and preserved for many years, and often through life. " The rapidity with Avhich caries progresses after the exposure of the bone by the loss of the enamel, depends upon the physical pecu- liarities of the teeth, and upon local and constitutional influences; hence the difficulty, and oftentimes impossibility, of obtaining the object for Avhich dental operations are instituted, while such influences are suffered to exist. If special regard is not had to the curative indica- SURGERY. 287 tions, most, if not all the operations upon the teeth, which have for their object their ultimate preservation, are sure, to a greater or less extent, to augment all of the previously existing local affections, by increasing the irritability of the parts, and by rendering them more susceptible of being acted upon both by local and constitutional causes. "Without indulging in further prefatory remarks, I shall proceed to notice more particularly the subject under consideration. And I would here observe, that an experience obtained from twenty-three years' constant practice, has fully convinced me, not only of the pro- priety, but of the absolute necessity in the treatment of cane? in the lateral surfaces of the teeth, of employing the file There is no instru- ment so well adapted as this for the removal of the disease when situ- ated in these parts of the teeth, especially when the organs are in close proximity with each other; or for the removal of rough and weakened edges of the enamel in deep-seated caries, and for making sufficient space or room for the removal of the diseased parts preparatory to plugging. "It maybe laid down as a rule,from Avhich exceptions should never be taken, that the file should not be used Avhile the teeth or their con- tiguous parts are suffering general or local, acute or chronic, inflamma- tion. Therefore, Avhen this is the case, the treatment of the general and local affections should precede the operation of filing. Upon the removal of all the acute or chronic diseases of the mouth greatly de- pends the success of the dentist in the treatment of affections of the teeth calling for the employment of the file. As much importance, therefore, is to be attached to an enlightened and discriminating judg- ment as to tact in the performance of the operation. "In fact, the removal of all local causes of irritation — such as dead roots of teeth, teeth occasioning alveolar abscesses, or such as exert a morbid influence upon the surrounding parts, and all deposi- tions of salivary calculus or other foreign matter — should precede all other operations upon these organs. "The length of time necessary for the restoration of the parts con- tiguous to the teeth may vary from a few days or weeks to as many months, depending upon the nature and extent of the disease, the general health of the patient, and the constitutional as well as local treatment to which they are subjected. " In assuming the position that filing the teeth does not, of necessity, cause them to decay, it is by no means to be inferred that the opera- tion can, in all cases, and under all circumstances, be performed with advantage or even impunity. Its effects, like those of most other opera- tions upon the teeth, when the curative indications are disregarded, or not properly carried out, are most injurious. The employment of the 288 SURGERY. file at an improper time and in an improper manner, increases the liability of teeth to decay ; it augments the irritability of all the parts adjacent to them, and consequently their susceptibility of being acted upon by local and constitutional causes. " The principal, and, I believe, only objection, urged against filing the teeth, is based upon the erroneous opinion, that the loss of any part of the enamel of these organs must necessarily result in their destruc- tion. But, if this be true, why is it, as I have on another occasion asked, that the negroes of Abyssinia have such sound teeth as they are represented to have; since it has long been a custom with them to file all their front teeth to points, so as to make them resemble the teeth of a saw or those of carnivorous animals ? Of course, large portions of the enamel and much of the bony structure, must be removed in the operation, yet we are credibly informed that their teeth seldom decay. The same may be said of the Brahmins of India, who, from remote ages, have been in the habit of using the file; principally, I believe, for separating their teeth, yet they too are noted for having fine teeth. I might refer to the people of other countries, with whom the same practice has long had an existence, but it is unnecessary to go abroad for proof, Avhen we have such an abundance of it at home, to establish the propriety and absolute necessity for the practice I am now advocating. " With the people just referred to, it is evident that they file prin- cipally for the purpose of ornamenting their teeth ; Ave use it only as a remedial agent in the treatment of disease. The reason Avhy their teeth are not so subject to disease as are those of the inhabitants of civilized countries, is attributable to the difference in their habits of life, mode of living, and to the absence of the causes productive of the various diseases peculiar to civilization and refinement. "Notwithstanding the utility and value of the operation, filing the teeth may be regarded as a predisposing cause .of caries. If this be true, it may be asked, why file at all ? I answer, in this country, owing to the prevalence of the immediate or direct cause of caries, the operation is only performed as remedial, for the purpose of re- moving actual disease or as preparatory to plugging. It does not, of necessity, follow that caries of the teeth, after having been judiciously removed or treated, although the organs be predisposed to the disease, will ever again occur. The general system often escapes the develop- ment of those diseases to Avhich it is predisposed through life; so also do the teeth. If the operation be properly performed, and the filed surfaces kept thoroughly clean, a recurrence of the disease, notAvithstanding the increased predisposition thus induced, will never take place. The immediate cause of dental caries being the contact of corrosive agents SURGERY. 289 with the teeth, the necessity for this precaution is obvious. The bony structure of these organs is more easily acted upon by such causes than the enamel; for this reason, when it becomes necessary to expose it with a file, for the removal of disease, it should be done in such a way as to admit of its being kept thoroughly and constantly clean; so that, if it afterward becomes carious, it will be owing altogether to inattention of the patient. In view of this, Avhenever it becomes neces- sary to file the teeth, whether for the complete removal of caries, or as only preparatory to plugging, we should ahvays impress upon the patient the importance of cleansing the surfaces thus operated upon at least three or four times every day. The future preservation of the organs will depend upon the constant and regular observance of this precaution, especially when they are of a soft or chalky texture, for they are then far more easily acted upon by decomposing agents than Avhen hard. " The cases requiring the use of the file vary so much that it would be difficult to lay down precise directions with regard to the extent to which the operation should be carried. This must be determined by the judgment of the operator The design of the operation may be defeated either by filing too much or too little. Either extreme should be avoided; but it is my opinion that by far the greater number of unsuccessful results are attributable rather to the too moderate than to the too great use of this instrument, especially where the circumstances of the case have nothing to do in determining the result. " It is not my object to describe the manner in which teeth should be filed, but merely to offer a few general remarks on the advantages that result from it Avhen the operation is judiciously performed; also to show that it is from the abuse of the file, in the hands of the igno- rant and inexperienced practitioner, that its merits have been so often erroneously estimated. It Avill be perceived, from the foregoing re- marks, that its utility depends upon carrying out all the curative indi- cations, and that it should never be resorted to except in the absence of disease in the parts Avith Avhich these organs are immediately con- nected. Therefore, to estimate the merits of the operation correctly, we should know all the circumstances under Avhich it has been per- formed, the competency of the operator, and Avhether he Avas permitted the free exercise of his judgment. The dentist is often called upon to render his services Avhere, from the timidity or ignorance of his pa- tient, he is, if he consents to operate at all, so restricted in the appli- cation of his remedies, that little, if anything, more than temporary relief can be afforded. And cases may occasionally occur in which, from unforeseen circumstances, even after the most skilful manage- 19 290 SURGERY. ment, the dentist may be disappointed in his expectations, and fail in the attainment of the object for which his services were solicited." It is scarcely necessary to give any directions with regard to the manner of holding the file. In filing the front teeth and those on the right side of the mouth, the operator should stand to the right and a little behind the patient, in order to steady the head, as it rests against the back of the operating chair, Avith his left arm; while with the fin- gers of the left hand the lips are raised and the teeth properly exposed for the operation. In filing the teeth on the left side of the mouth, it may be necessary for the operator to stand upon the left side of his patient. The file, firmly grasped between the thumb and middle finger of the right hand, with the end of the forefinger resting upon its outer end, should be moved backAvard and forward in a direct line, as any deviation from this Avould immediately snap the instrument. The first opening between the teeth, Avhen the approximal edges of the tAvo are carious, should be made with a flat file, about one-fourth of a line in thickness, cut on both sides and both edges; this done, a file cut on One side and both edges should be employed for the completion of the operation. If only one tooth is decayed, the operation may be com- menced and completed with a safe-sided file. The file, during the ope- ration, should be frequently dipped in tepid water, to prevent it becom- ing heated or clogged Avhile in use; especially should the water be warm or tepid Avhere the teeth are sensitive. When the files become so much clogged that the Avater or a brush Avill not cleanse them, a brass or steel scratch-brush may be used, or they may be dipped in sulphuric or chlorohydric acid, and then washed with the greatest care to remove every trace of acid. Fig. 57. Fig. 57 represents various forms of the thin separating file. To secure the success of the operation, it is sometimes necessary to file away a considerable portion of the tooth ; but in doing this, the operator should be careful not to destroy the symmetry of the labial surface. The aperture, anteriorly, should only be Avide enough to admit of a free oblique or diagonal motion of a safe-sided file of about SURGERY. 291 one-fourth of a line in thickness. In this way, one-fourth or more of a tooth may be removed Avithout materially altering its external ap-r pearance. But a tooth should not.be filed entirely to the gum,; a shoulder should be left, to prevent its approximation to the adjoining tooth. Sometimes the decay is of such size and so situated, that it may be removed by means of enamel chisels, Avith less alteration in the external or labial surface of the tooth. These very valuable instru- ments Avill also be found useful for rapid cutting preparatory to the slower action of the file. A rounded form can be given by them to the inner angles of the teeth, for Avhich purpose they may either folloAV or take the place of the file. Fig. 58. n n n i Fig. 58 represents a set of enamel chisels, straight and curved, By which the operation of removing a portion of the crown of a tooth can be performed much more rapidly than by the file, and also with more comfort to the patient. When operating upon the front teeth Avith the enamel chisel, the instrument should be firmly grasped in the hand, and ii:j edge applied to the surface of the portion to be removed, Avhile at the same time the point of the thumb uses as a fulcrum the cutting edge of the tooth or the one adjoining. For operating upon the bicuspid and molar teeth, heavier enamel chisels are required than in the case of the front teeth, and Avith cither straight or oblique cutting edges. The curved form of chisel is useful Avhen the mouth is small, and it is difficult to reach the point desired with the straight form. When the decay occupies a large portion of the approximal surface, and has penetrated into the tooth to a considerable depth, destroying the enamel anteriorly, and causing it to present a ragged and uneven 292 SURGERY. edge, it will be necessary to form a wider exterior aperture than mere regard for appearance would dictate. When the approximal surfaces of the two front teeth are affected with caries, about an equal portion should, if circumstances permit, and it is necessary to cut away tooth substance, be filed or cut from each tooth. In the case of delicate front teeth, or teeth slightly loose in their sockets, it will be well before filing to mould a small piece of gutta-percha around or against the inner surfaces of the tooth to be filed and several adjoining ones. It gives support to frail teeth, and greatly lessens the danger of irritation from the motion imparted by the file to teeth which are not firmly set in their sockets. Some use for this purpose plaster; but Ave think the gutta-percha, as suggested by Prof. Gorgas, will be found altogether more conveniently applied and more agreeable to the patient. Fig. 59 represents a front view of the superior incisors and cuspids aftfer having been filed, showing the shoulder left near the gum; which, hoAvever, should not have the sharp angle represented in the draAving. To prevent this, the operation may be completed with a round-edged separating file, or else Avith a delicate mouse-tail file. :After a sufficient portion of the tooth has been filed away, the sur- fape should be made as smooth as possible with a very fine or half worn file, or with Arkansas stone, finishing Avith pumice-stone or pow- dered silex, applied upon a piece of cord, tape, or suitably shaped piece of hard, tough Avood. All edges and sharp corners should be rounded and made smooth, and Avhen the operation is completed, the patient should be directed to keep the filed surfaces perfectly clean ; for if the mucous secretions of the mouth or extraneous matter is permitted to adhere to them, a recurrence of the disease will take place. In Fig. 60 is represented a poste- rior vieAV of the superior incisors and cuspids after having been filed; also, of the bicuspids and molars after having been subjected to the same operation. In separating the bicuspids by filing, a space should be made some- what in the form of the letter V ; it should not, hoAvever, form an acute angle at the gum. For its forma- tion, a file shaped like a clockma- ker's pinion-file, or one that is oval on one side and flat on the other, will be found most suitable. A SURGERY. 293 space shaped in this manner will prevent the approximation of the sides of the teeth, and if filling be necessary, it will enable the operator to do it in the most perfect manner. When the separation of the molar teeth in this manner becomes ne- cessary, the same shaped space should be formed. But as these teeth are situated far back in the mouth, it cannot often be done with a straight file; to obviate this difficulty, an instrument, Avith Avhich every dentist is acquainted, denominated a file-carrier, is usually employed. But in consequence of the difficulty of procuring instruments of this kind exactly suited to holding files of the right shape, the author, a number of years ago, sent some file patterns to Stubs' manufactory, in England, and had files made, which he found to answer his fullest expectations. These files (Fig. 61) are shaped something likea pinion- Fig. Gl. file: they are an inch and a half long, and have a handle of about six inches in length, bent in such a manner that the instrument may be used between the molar teeth without interfering with the corners of the mouth. They are in pairs — one for the right and one for the left side of the mouth. Two patterns are represented ; the upper, in con- sequence of the handle being on a line with the file, works more easily than the lower one. A great variety of V-shaped separating files are now to be found in the dental depots, from English, French, and American manufacturers. Fig. 62 will give a correct idea of some of these shapes. Fig. 62. 234 SURGERY. Fig. 65 represents a very useful file-carrier invented by Dr. A.; Westcott: cis a spring, and through the arms a and b there are square Fig. 63. mortices to receive the ends of the file and to keep it from turning. The arm b comes off at an obtuse angle. The file is prepared by making each end square, corresponding Avith the size of the mortices in the arms, and is adjusted to the carrier by first putting one end of the file into the arm a, and pressing down the other end into the mor- tice b; the spring, constituting that portion of the instrument between the arms, yields sufficiently to admit of this. It is so constructed that the handle is brought on a line Avith the file; consequently two are required, one for each side of the mouth. Fig. 64. Fig. 64 represents an excellent file-carrier, in which the file can with ease be set at any required angle, and will suit either side of the mouth. , ' Fig. 65. Fig. 65 represents one of the best forms of file-carrier in use, in- FILLING TEETH. 295 vented by Dr. W. G. Redman. This instrument may be readily changed from one side to the other, and retains the file very firmly. Fig. 66. Fig. Q6 represents another form of file-carrier to which the file is very readily adjusted. For separating the teeth to obtain space for the free use of the in- struments employed in preparing and filling cavities on the approximal surfaces, the reader is referred to the chapter on filling teeth. CHAPTER II. FILLING TEETH. THIS is one of the most difficult operations the dentist is called upon to perforin ; it often baffles the skill of operators who have been in practice many years. It is advisable only under certain cir- cumstances, and when the operation is performed Avithout due regard to these, it may be productive of injury rather than benefit. It is the only certain remedy that can be applied for arresting the progress of deep-seated caries; but to be effective, it must be executed in the most thorough and perfect manner. The preservation of a tooth may be regarded as certain when Avell filled, and with a suitable material, if it be afterward kept constantly clean. At any rate, it will never again be attacked by caries in the same place. . On this highly important operation, Dr. E. Parmly thus remarks: " If preservation is as good as a cure, this is as good as both; for the operation of filling, when thoroughly performed, is both preservation and cure. And yet it must never be forgotten, that this assertion is true only in those instances in Avhich the operation is well and properly done; and perhaps it is imperfectly and improperly performed more frequently than any other operation on the teeth. "There are reasons for this fact, into Avhich every ambitious and honorable practitioner will carefully inquire. Although the books are explicit on this point, I deem it sufficiently important to deserve a few additional remarks. The folloAving considerations are essential, and, therefore, indispensable to success in this department of practice. 296 FILLING TEETH. Firstly. The instruments used must be of the proper construction and variety. Secondly. The metal employed must be properly prepared as well as properly introduced. Thirdly. The cavity which receives the metal must be so shaped as to retain it in such a manner as to exclude not only solids, but all fluids, and even the atmosphere itself. Fourthly. The surface of the metal must be left in such condition as to place it beyond the reach of injury from food and other mechanical agents with which it necessarily comes in contact. Fifthly. The tooth thus filled should be free from pain and every known cause of internal inflammation." It is important that the operation be performed before the disease has reached the pulp-cavity; after this, the permanent preservation of the tooth may be regarded as more or less questionable. Still, under favorable circumstances, the author believes it may, in the majority of cases, be performed with success. But, as the propriety and manner of filling a tooth after the pulp has become exposed, will hereafter come up for special consideration, as well, also, as the operation of filling the pulp-cavity after the destruction of the pulp, it will not be necessary to enlarge upon these subjects at this time. A tooth is sometimes exceedingly sensitive when the nerve is not ex- posed ; but, in the majority of cases, this need not deter the operator from removing the decayed part and filling the eavity, for the inflam- mation of the dentine may be confined to a thin lamina directly beneath the carious matter, and the only inconvenience it will occa- sion the patient, will be a little suffering during the operation, and slight momentary pain for a few days, whenever anything hot or cold is taken into the mouth. But when the sensibility is so great, owing to the inflammation extending deep into the structure of the dentine, that the patient cannot bear the removal of the diseased part, as occa- sionally occurs, it may be allayed by the application of chloride of zinc to the cavity of the tooth, for from three to six minutes. When this is done, care should be taken to prevent it from coming in contact with any of the soft parts of the mouth, on account of its active escha- rotic properties. The fortieth or fiftieth part of a grain of arsenic is sometimes applied, and alloAved to remain from one to three hours ; but there is great danger of destroying the vitality of the pulp by the use of this agent, even though it be permitted to remain for only a few hours. Cobalt is said to be less dangerous and equally efficacious. Tannin or tannic acid in alcoholic solution, or in creosote and glycerin, are valuable applications for this pathological condition of the dentine. Nitrate of silver, chromic acid, and the terchloride of gold are also used for the same purpose — the nitrate being applied in either a solid form or in a concentrated solution; and while it affects the dentine to a FILLING TEETH. 297 greater depth than either the tannic acid or chloride of zinc, yet its action is not so painful as the latter. Creosote and carbolic acid are extensively used for this condition of dentine, and are among the safest of these agents. Friction, by means of a burnisher, is also recommended as being effect- ual where the position of the sensitive surface will permit of its use. Chloroform applied to the cavity on a small piece of cotton will often give a temporary insensibility, and has the merit of being quite harm- less ; which cannot be said of chloride of zinc, arsenic, or cobalt — the first sometimes acting injuriously upon the dentine, the two latter upon the dental pulp. The safest and perhaps best way of meeting the diffi- culty is to have the excavators very sharp and well tempered, and to cut firmly and decidedly,—for the scraping of a dull instrument is quite as painful as the cut of a sharp one,— and, after removing irritants from the sensitive surface and properly preparing the cavity to fill it with a non- conducting substance, such as Hill's stopping, prepared gutta-percha, or os-artificiel, Avhich is alloAved to remain until the dentine is restored to a normal condition. Should it, however, be necessary to fill the cavity Avith a more permanent material, such as metal, and the inflammation is confined to a portion of the dentine, this may be protected by a layer of the non-conducting material, and the metal introduced over it. Again, this acute sensitiveness of dentine is due to the presence of nerve fibres, as conjectured by Dr. Maynard, and demonstrated by Prof. Johnston; therefore, we shall save the patient much suffering by making the first strokes of the instrument in such direction as to sever these fibres, as recommended by Dr. Maynard. MATERIALS EMPLOYED FOR FILLING TEETH. Among the articles which have been employed for filling teeth, are gold, platina, silver, tin, lead; fusible alloys of tin, lead, bismuth, and cadmium ; amalgams, gutta-percha, oxychloride of zinc, and various preparations of the gum resins. Of these no single one can be said to unite all the requirements of a perfect material for filling, Avhich may be enumerated : 1. Resistance to the mechanical action of mastication. 2. Resistance to the chemical action of the mouth. 3. Facility of in- troduction and consolidation. 4. Harmony of color. 5. Absence of all galvanic, chemical, or vital action upon the teeth or the general system. 6. Absence of all heat-conducting property. Gold Foil. — To the use of this material, when properly prepared, there is the least possible objection : perfectly answering the first, second, and fifth requirements ; to a great extent the third, if in skilful hands; but deficient in the fourth and sixth. It is the only one, in the opinion of the author, Avhich should ever be employed for the permanent filling 298 FILLING TEETH. of teeth. No better material is wanted for the operation. A tooth may be so filled Avith it as to secure, in almost every case, its permanent preservation. It should, however, be perfectly pure, be beaten into thin leaves, and Avell annealed, by the manufacturer, before it is used. When prepared in this manner, it may be pressed into all the inequal- ities of the cavity, and rendered so firm and solid as to be impermeable to the fluids of the mouth.* Although there may be no difference in the purity of the gold and the thickness of the leaves, yet a marked difference will be found to exist in the malleability and toughness of the foil of different beaters. The art of preparing gold for filling teeth is an exceedingly nice and difficult one, and is believed to have attained greater perfection in the United States than in any other country; at least this fact is so generally admitted, that many of the most eminent European practitioners pro- cure nearly all they use from Mr. Charles Abbey, of Philadelphia, the oldest manufacturer in America. There are, however, many other gold-beaters in the United States who manufacture gold foil of a very excellent quality. The thickness of the leaves is determined by the number of grains each contains, and is designated by numbers on the books, between the leaves of which they are placed, after having been properly annealed. These numbers range from 4 to 20. The weight of the leaves, gen- erally, varies two grains, so that the numbers run 4, 6, 8, 10, and so on up to 20. A book containing a quarter of an ounce of No. 4, will have thirty leaves in it. Some dentists use foil varying in numbers from 4 up to 20, and even of late to 120, while others confine themselves to a single number. If but one number of the non-adhesive be used, 4 will, perhaps, be found better than any other. The author has used Nos. 4, 6, 8, 10, and 15, but he prefers the first, and is decidedly of opinion, that in a large majority of cases, a better filling can be made with it than any of the others. There may be cases in Avhich higher numbers can be more advantageously employed ; as for instance in root filling, and in cavities Avhich are either very large or very small. Adhesive Gold Foil. — This is a preparation of leaf gold Avhich possesses the property of cohesion to such a degree that the leaves * It would seem from what Fauchard says upon the subject (Le Chirurgien Dentiste, tome 2, pp. 68-70), that this metal, to some extent at least, lias been used for filling teeth for a long time. Although he gives the preference to tin and lead, on account of the greater malleability of these metals, he speaks of gold as being used by other dentists. But the operation of filling teeth, at the time this author wrote, was very imperfectly understood, and the gold then em- ployed for the purpose must have been so badly prepared as to render its use exceedingly difficult. FILLING TEETH. 2S9 readily and firmly unite on being pressed together with moderate force. Although one or two others claim priority in the discovery of the advantages now derived from the use of adhesive gold foil, yet the credit is certainly due to Dr. Robert Arthur, as he Avas not only the first to demonstrate the applicability of this form of gold in filling teeth, but in a series of well written articles * he overcame the objec- tions Avhich were at first urged against it, and proved that its great cohesiA^e property rendered it a valuable adjunct in the preservation of the teeth. This form of foil is so adhesive that any number of pieces may be welded one to another; thus a part, or even the Avhole of the crown of a tooth, may be built up with it. The same property may also be imparted to foil manufactured in the ordinary Avay, by re- annealing. This property is peculiarly valuable in many cases where it becomes necessary to build up a large portion of the crown of a tooth ; but when it is used, instruments having serrated points are re- quired, like those employed in the use of crystal or sponge gold. Crystal or Sponge Gold has been employed by dentists for filling teeth for a number of years. The author has used it in a number of cases with very satisfactory results. Since the publication of the fifth edition of this Avork, the properties of crystal or sponge gold have been more thoroughly and extensively tested, and the result has fully con- firmed the favorable opinion entertained by us with regard to its value. Those who have had most experience in the use of it say it is superior, in many cases, to foil. The author is acquainted with several of the most skilful operators in the United States, who have used it almost exclusively in their practice for several years; and has seen fillings made by some of these gentlemen, Avhich for beauty and solidity he does not think could be surpassed. He has also himself made some fillings with this material, Avhich he believes it would be impossible to make Avith ordinary gold foil. This form of gold has a spongy texture, being composed of crystals, and Avidely differs from foil or leaf gold. The crystals possess the property, Avhen pressed firmly against each other, of welding and becoming as solid and almost as incapable of disintegration or crumbling as a piece of bullion or coin. This prop- erty enables a skilful manipulator to supply almost any loss Avhich a tooth may have sustained, even to the building up of an entire crown. Still, it will never supersede the use of adhesive and non-adhe- sive gold foils, as there are many cases in Avhich leaf gold can be used more advantageously and Avith more facility. Nor will the employment of it, in the opinion of the author, ever become universal; for the * A Treatise on the Use of Adhesive Gold Foil, 1857. 300 FILLING TEETH. reason that more care and skill are required to make a good filling with it than with leaf gold, especially when the cavity in the tooth is difficult of access. Filling with crystal gold is more tedious than the same operation with ordinary foil. Again, the necessity of exclud.ng saliva from the filling during the operation is imperative; for the slightest moisture destroys the adhesiveness of the material, upon which depends the success of the operation. Experiments have been made with silver, platina, and aluminium; but with unsatisfactory results. They are less malleable than gold, and therefore cannot be made so thin; at the same time they have not the softness of tin ; hence they work harshly under the plugger. But for this, platina would prove a very valuable material. An additional objection to silver is its liability to undergo chemical change, being in this respect greatly inferior to pure tin. The peculiarity of aluminium, in this relation, is the impossibility of welding its leaves by pressure: even under the gold-beater's hammer it forms loose scales, which no annealing can make adherent. Tin Foil.— This, when chemically pure and properly prepared, is less objectionable for filling teeth than most of the articles hereafter enumerated. Under favorable circumstances, if skilfully introduced, it will prevent the recurrence of caries. But if the fluids of the mouth are vitiated, it soon oxidizes and turns black ; and then, instead of preventing, it rather promotes a recurrence of the disease. This, with the author, has constituted an insuperable objection to its use. As an excuse for its employment, hoAvever, many operators say that, in consequence of its greater softness, it can oftentimes be employed for filling a badly shaped and large cavity Avhere gold cannot be used. We do not, however, regard this as a valid objection ; for any tooth that can be filled with tin, can be equally well filled Avith gold. Others again employ it because many of their patients are not able to pay for a more costly material. Now, if a tooth is worth filling at all, it is worth filling in a proper manner, and with a suitable material, and it would be more creditable to the operator to divide the expense with his poor patient, than to use an article that may never benefit him. Lead is far more objectionable than tin, as it is more easily decom- posed by the secretions of the mouth ; its introduction into the stomach might be productive of serious injury to the general health of the patient. But, happily, this article is now seldom used, except by the most ignorant and lowest class of empirics. D' Arcet's and Wood's Metals.— D'Arcet's metal, an alloy of tin, lead, and bismuth, Avas once empirically used in a fused state. But two serious objections compelled its abandonment. The high tempera- ture (212°) caused great pain and excited inflammation. If from FILLING TEETH. SOI this cause the tooth was not lost, the shrinkage of the metal on cooling admitted moisture into the cavity, and the decay progressed. The attention of the profession has recently been called to a some- what similar alloy, discovered by Dr. B. Wood. The feature of Dr. Wood's discovery is the remarkable property of cadmium in reducing the fusion point of the fusible alloys. This overcomes in good measure the first objection against D' Arcet's metal, and the second perhaps altogether. It may be introduced in properly sized pieces, cold; then made plastic and pressed to place with blunt instruments suitably shaped and heated to the proper temperature. Over a sensitiAre pulp a layer of non-conducting asbestos may be interposed. We cannot speak from any experience in its use, but should think that it might be experimented with in certain cases, where the use of gold is inad- missible, and where there is little or no danger of irritation from the elevated temperature necessary to its use. Amalgam, also known by the name of mineral cement, or lithodeon, is now composed of about equal parts, by weight, of banca tin, silver, pure as coin, and a little platinum. These metals are melted in a cru- cible and poured into ingots, which are then cut up Avith a file into filings. These filings are mixed, after the cavity in the tooth is pre- pared for the filling, with about thirty-three and one-third per cent. of distilled mercury, and incorporated to the consistency of a thick paste. The mass is then thoroughly washed with alcohol, to Avhich is added a feAV drops of a strong solution of chloride of zinc. The ex- cess of mercury is then removed by twisting the mass in a piece of chamois skin or strong muslin. It is also recommended to press the mass quite thin, after it is removed from the chamois skin, Avith a strong pair of flat pliers, in order to remove still more of the mercury. When this is done, it may be necessary, in introducing the amalgam into the cavity, to heat the point of the condensing instrument, in order to soften the material and bring to the surface any excess of mercury which may yet remain in it. The cavity should be prepared with as much care as for a gold filling, and moisture prevented from coming in contact Avith it. When the cavity approaches near to the pulp, some non-conducting substance should be applied betAveen the amalgam and the bottom of the cavity. After the filling has become sufficiently hard, its surface should be carefully finished by filing and burnishing. Fig. 67 represents a set of Avhat are knoAvn as Arrington's amalgam instruments. The objections urged against amalgam are, that it oxidizes and blackens ; that the tooth structure, with Avhich it remains in contact, becomes discolored ; that it contracts in hardening, allowing the secre- 302 FILLING TEETH. tions to make their way around the filling. The use of amalgam is contra-indicated in all teeth which can be filled with either gold or Fig. 67. tin foil; in the front teeth on account of its color; in approximal sur- face cavities of bicuspids and molars, as these cavities are the most difficult to properly protect, and hence should not be filled with any but the best material in use; in pulp cavities; in contact with gold fillings. On the other hand, the use of amalgam is indicated in teeth, the crowns of Avhich are mere shells — so far gone that nothing else Avill answer, and it is desirable to preserve them for a short time. That it is a very convenient material; can be put where gold can- not; becomes very hard, and may last for many years, Ave doubt not; but nothing Ave have seen, read, or heard, can persuade us that the profession would not have been benefited if mercurial amalgams had never been known. Gum Mastic, at one time much used, is noAv seldom employed, except as a temporary filling Avhen the pulp of the tooth is exposed ; even for this purpose it requires to be often reneAA'ed, as it is soon dissolved by the saliva. An alcoholic solution of Gum Sandarach or Mastic is sometimes used to retain arsenical preparations in the cavity for the destruction of a nerve. A piece of cotton saturated Avith the solution is readily introduced, hardens quickly, and may keep its place for several days if required. Gutta-Percha and Hill's Stopping.—Gutta-percha is an excellent material for temporary fillings. It may be made harder, whiter,and less contractile by incorporating with it some very fine poAvder of felspar, silex, lime, or magnesia. A very excellent preparation knoAvn as Hill's stopping is made by mixing gutta-percha with as much of the following powder as it Avili hold Avithout becoming brittle : quicklime, FI L L r N G TEETH. 303 t>vo parts, very fine quartz and felspar, one part each. Of all tem- porary fillings this is probably the best yet known. Prepared gutta- percha and Hill's stopping are introduced by first warming on a por- celain or metal slab, over an alcohol lamp, until the mass is plastic enough to be readily pressed into the cavity and to adhere to its Avails. As soon as the cavity is filled, an instrument, having a condensing point large enough to cover the entire surface of the filling, should be applied and kept in position until the mass has become cool. The surface of the filling is then cut down and burnished, after which a little chloroform may be applied by means of a camel's-hair brush, to complete the finishing process. Os-Artificiel— Oxychloride of Zinc.—A mixture of chloride of zinc and oxide of zinc has been lately much used under the various names of oxy- chloride of zinc, os-artificiel, osteo-dentine, osteo-plastic, mineral paste, etc. Quackery has seized it Avith eagerness, and plastered up many teeth with a mortar even more conveniently used than amalgam. Although in some few cases it may resist the action of the secretions of the mouth, it will not ansAver for a permanent filling. The friction of mastication soon destroys it, so that for temporary fillings it answers a better purpose in approximal surface cavities than in those on the grinding surfaces. Frequently it crumbles aAvay in a few Aveeks or months. Still, as a temporary filling, it may, if employed Avith caution and judgment, be found useful, and for certain cases very valuable. It has been recently used with success for filling the pulp cavities of the teeth, possessing, for such a purpose, an advantage over gold in being a non-con- ducting substance. It answers a good purpose Avhen placed in contact with sensitive dentine, which is OAving to the escharotic action of the zinc, as Avell as its non-conducting property. It has also been applied successfully to exposed nerves, and gold introduced over it. In using os-artificiel, the cavity is prepared as usual ; then a small quantity of the liquid (chloride of zinc) is dropped upon a piece of glass or por- celain, and enough of the poAvder (oxide of zinc) added to make a paste so thick that the surface will not appear Avatery. The cavity is then perfectly dried and protected from saliva and the material quickly introduced, after which it is kept free from moisture for ten or twenty minutes. When sufficiently hard, the surface is finished by scraping and polishing. The longer the surface is kept dry the harder this material becomes. Coating the surface with sandarach varnish "will afford protection for some time. INSTRUMENTS FOR FORMING THE CAVITY. For the removal of the diseased part of the tooth, and the formation of a cavity for the proper reception and retention of a filling, a variety 301 FILLING TEETH. of instruments are required, which should be constructed of the best steel, and so tempered as to prevent them from either breaking or bending. Their points should be so shaped that they may be con- veniently applied to any part of a tooth, and made to act readily upon the portion Avhich it is necessary to remove. Fig. 68. The instruments employed for this purpose are called excavators. Fig. 68 represents a feAV of the many forms of excavators in use. They may be formed either with handle and point in one piece or fitted to separate handles made of Avood, ivory, pearl or cameo ; or be made to fit into one common socket handle. Those having separate handles are more convenient than the others, but it Avould be Avell for every practitioner to be provided with a number of each kind. Steel- handled excavators are cheaper than wooden or ivory handled ones; but if small they are not so easily grasped, and if large they become too heavy. The handle best suited for delicate manipulation is made of cocoa or ebony, largest an inch above the ferule, and tapering both ways. The principle of construction is to give sufficient size for the fingers to hold it securely, and to lessen the Aveight at the end of the handle. Socket handles are useful for those Avho wish compactness of apparatus; also for those who are in the habit of pointing their own instruments. Fig. 69 represents such an instrument: the lower one, Fig. 69. made of ivory, ebony, or cocoa, Avill be found very valuable. Its shape might be better suited to some operators if made someAvhat larger just above the ferule. The flat and burr-headed drills represented in Fig. 70 are very FILLING TEETH. 305 Fig.71. useful for enlarging the orifice of a cavity. The pressure of the instru- ment against the hand, between the thumb and FlG- /0- forefinger, is often pro- ductive of much irrita- tion. To prevent which, a socket-ring or shield, like the one represented in Fig. 71, invented by Dr.Westcott, may be used Avith advantage. It con- sists of a ring adapted for the fore or middle finger, with a small socket at- tached to the inside. The author uses an open ring, like the one repre- sented in Fig. 72, with an arm a little more than an inch in length attached, having a socket at the extremity resting in the hollow of the hand, be- tAveen the thumb and forefinger. This he finds much more convenient, as it enables him to apply more pressure upon the instrument without irri- tating the finger, and, as the ring is open, it adapts itself more readily to it. A socket handle may also be used for drills as for excavators. It may be shaped like the exca- vator socket (Fig. 69), with the end of the handle pointed so as to fit into the ring i Figs. 71, 72); or it may have a flattened revolving head. The bits may be fitted either by firmly pressing them into a simple round socket, or a trigger socket may be used. Fig. 73 represents a short revolving head socket for the palm of the hand, by means of which the ordinary drill can be rotated Avithout chafing the hand. Dr. Forbes has adapted to enamel burrs, chisels, and gouges an ingenious handle, which, by the simple 20 Fig. 72. C06 FILLING TEETH. turning of a small wrench, secures the square-cornered bits very firmly (Fig. 74). The principle may be applied to handles of different shapes and sizes, provided they are not too small. Fig. 73. Fig. 74. The old-fashioned bow-and-string drill is now disused, partly because of its formidable appearance, but chiefly because there is danger of revolving it with too great rapidity. Many very ingenious forms of drill-stocks have been, from time to time^ invented; of these we pre- sent several. The instrument represented in Fig. 75 is a modification of a very Fig. 75. ingeniously contrived drill-stock, invented by Dr. Maynard, for open- ing a cavity in the grinding, buccal, or posterior approximal surface of Fig. 76. a molar tooth. It is so constructed as to move a drill, pointing in three different directions; but, as in the case of the drill-stock used FILLING TEETH. 307 with a bow, the original instrument required both hands to work it. To obviate Avhich difficulty, it has been so improved, that it may be used with one hand, as shown in Fig. 75. Two drill-stocks Avere presented to the author some years ago, the first (Fig. 76) by Dr. James Robinson, of London, invented by Mr. McDowell, of Lincoln's Inn Fields. It is upon the principle of the helix. A drill-stock, inserted at the end of the screw, is moved by means of a female screw attached to the handle of the instrument. As may be seen from the engraving, drills pointing in three directions may be worked in it. The other was presented by Mr. John Lewis, Fig. 77. formerly of Burlington, Vt. (Fig. 77.) It is a beautiful and ingeni- ously contrived instrument. The drill may be worked in any direction within its circle of motion, from the line of the handle round to the same line again. Fig. 78. Fig. 79. Fig. 78 represents Chevalier's drill-stock, by which the drill can be brought to bear in different directions. Merry's drill-stock (Fig. 79), more recently invented, is simpler than the preceding, and will, doubtless, prove useful in cases where such instru- ments are necessary. For opening a ca- vity in the grinding surface of a tooth, partially covered by projecting portions of the enamel, the rose or burr-headed drill is invaluable, and it can often be advan- tageously applied to the side of a tooth. There are many cases, too, where the flat triangular-pointed drill can be conveniently employed, as, for example, when it becomes necessary to extend the cavity further 308 FILLING TEETH. into the tooth than the disease has penetrated. When the drill is used, it should be frequently dipped in water to prevent its becoming heated by the friction against the tooth ; this precaution ought never to be neglected. A three-sided instrument brought to a point (Fig. 80), as also a chisel-edged (Fig. 81),and a four-sided one with a cutting edge (Fig. 82), Fig. 80. Fig. 81. Fig. 82. may often be used advantageously in cutting away portions of enamel to enlarge the orifice. Enamel chisels of other shapes and gouges are Fig. 83. also very valuable instruments for the prelimi- nary operation of opening large cavities, or cutting off sound enamel or dentine Avhenever necessary. Dr. Forbes, of St. Louis, has devised a series of very useful forms of the enamel gouge Avhich are adapted to the handle in Fig. 74. But the cavity can seldom be completed with either of the instruments mentioned above. After it has been opened, and the orifice made sufficiently large, it should be finished with flat or curve-pointed excavators (Figs. 68 and 83), properly adapted to the purpose; in fact, in the majority of cases, it should be Avholly formed with instruments of this sort. Excavators, shaped like those represented in Figs. 68 and 83, have been found by the author to be as well adapted to the removal of caries as any which he has ever employed. There should be several sizes of each shape ; also duplicates of each instrument, to prevent delay in case of accident Avhile operating. As the proper formation of the cavity greatly depends on having suitable instruments, every operator should be provided with a large supply of burr-drills and excavators, so that lie may never be at a loss for such as the peculiarity of any case may require. He should also have the material, and knoAV Iioav, in an emergency, to point his own excavators. For this purpose he will need a lamp, a small anvil and hammer, a set of fine-cut files, such as are used by watchmakers, and an assortment of steel rods of various sizes and of the best quality. It is not our purpose to give specific directions for working steel; but we would offer two cautions : first, small points FILLING TEETH. 309 quickly become brittle by hammering and need frequent annealing: second, steel is greatly injured by raising it to a full red or white heat A very fine temper may be given, after shaping the point, by heating to redness and suddenly plunging it in wax or talloAV. As excavators must be kept very sharp, an oil-stone should be con- stantly at hand. The Arkansas stone is superior for this purpose to all other varieties, on account of its hardness, fineness, and sharpness of grit. MANNER OF FORMING THE CAVITY. The preparation of the cavity in a tooth for the reception of a filling, is a very essential part of the operation, and though usually the easiest, is sometimes attended Avith much difficulty. The removal of the diseased part is sometimes all that is necessary, preparatory to the introduction of the gold; but in the majority of cases the cavity must be so shaped, as, when properly filled, to retain the filling in place. The part of the tooth surrounding the orifice should present no rough or brittle edges. The size of the bottom of the cavity should be as near that of the orifice as is possible, even a little larger rather than any smaller. But the difference between the size of the one and the other should never be very great; for if the interior of the cavity is much larger than the orifice, it will be difficult to make the filling sufficiently firm and solid to render it absolutely impermeable to the fluids of the mouth* If, on the other hand, the orifice is larger than the bottom of the cavity, it will be difficult to obtain sufficient stability for the filling, so as to prevent it from ultimately loosening and coming out. It often happens, however, that the situation and extent of the decay is such as to render it impossible to make the cavity so large at the bottom as at the orifice; when this is the case, several pits or circular grooves should be cut in the inner walls, for the purpose of obtaining as much security for the filling as possible; being careful to make these in the dentine rather than in the enamel, which is so much more brittle. By proper atten- tion to this precaution, a filling may be so inserted, in this difficult class of cases, as to prevent it from coming out. As a general rule it is easier to form a cavity in the grinding surface * Place a lump of cotton in the hollow of the hand, formed by bringing the ends of the fingers against the palm. Then press with an instrument upon the centre of the cotton, and it will leave the sides of the cavity. This simple illus- tration, suggested by Dr. Edward Maynard. will explain the cause of failure, in certain cases which have come under his notice, from the hands of operators of deservedly high reputation. The cavity, smallest at the orifine, had beon well filled; but the final compres- sion upon the centre had drawn the gold from the sides, thus permitting the access of fluids, and ultimately decaying the tooth around the filling. 310 FILLING TEETH. of a molar or bicuspid, than in any other position ; though it some- times happens that even here it is attended with difficulty, and espe- cially when the decay, commencing in the centre, follows the several depressions which run out from it. In such cases the edges bordering on and covering the affected parts, which are often thick and very hard, should be cut away, together with the subjacent decayed dentine; the radiating depressions should open fully into the central cavity, and be made sufficiently wide and deep to admit of being filled to their extremities in the most.perfect and substantial manner. The surface of a filling occupying a cavity of this kind presents a sort of stellated appearance. When tAVO or more decayed places are separated only by very thin walls of tooth substance, these should be cut away, and a cavity formed large enough to include all the diseased points; as one large filling will secure the preservation of the tooth more effectually than by filling each cavity separately. Sharp angles should be avoided, as far as possible, in the outline of the orifice of the cavity, because of the extreme difficulty of filling them compactly. The orifice must also have a firm, decided margin, Avith no thin projecting edges of enamel on the one hand; with no countersunk depressions on the other. In the first case the thin enamel is apt to break off either during the operation or subsequently ; in the second case the thin scale on the edge of such fillings breaks aAvay in the course of time; in both cases the filling fails perfectly to answer its purpose in the preservation of the tooth. It is preferable, in many cases of front approximal fillings, to cut away the inner angles of the tooth, thus avoiding the injury to the external appearance of the tooth caused by the file. Upon completion of the operation, the surface thus cut is perfectly polished, as every filed or cut surface upon the teeth should be, and so shaped as to be kept readily cleansed Avith the brush or with floss silk. It is also very important that all the edges of cavities should be smooth and polished before and after the introduction of the filling. In forming a cavity for the reception of adhesive gold foil and crystal gold, it is very necessary that it should be of such a shape as to retain securely the first gold introduced, and to accomplish this, one or more small cavities, called retaining points, are made Avithin the larger cavity. These retaining, points in many cases afford anchorage for the entire mass of gold composing the filling, and in every case Avhere these forms of gold are used, they are the support in the building up from the bottom to the orifice of the cavity. These retaining points are formed in the dentine by means of a small square or chisel-edged drill, and can \rery often be made of one-sixteenth of an inch in depth; a less depth, however, will ansAver in FILLING TEETH. 311 many cases. One of these retaining points in connection with one or two under-cuttings on the opposite Avail will be sufficient in some cavi- ties, while in others two or three are required. The gold should be introduced into these retaining points in such a manner as to form, when they are filled, solid masses of metal, Avhich Avould require con- siderable force to dislodge them. Upon these solid masses the gold filling the cavity is built. Separating Teeth.—Before a cavity can be prepared in the approxi- mal surface of a tooth, it is usually necessary to separate it from the adjoining one. This may be done either with a file or by the pressure of some interposed elastic substance. Each of these methods has its advantages. When caries has extended over nearly the whole approxi- mal surface, so that, after the removal of the diseased part, the orifice of the cavity will be surrounded by a thin, brittle, and irregular Avail, the former is the preferable method; especially in individuals having a decided scorbutic tendency, or Avho have suffered from the use of mercurial medicines or syphilitic disease, and in aged persons. But when the caries has spread over only a small portion of the surface of the tooth, and is surrounded by sound, healthy enamel, the latter method should be adopted; especially in individuals in whom there is no manifest tendency to inflammation or sponginess of the gums, and in young subjects. The manner of separating teeth with a file has been already described; it will only be necessary, therefore, in this place, to offer a few remarks on separating by pressure, which was first adopted by Dr. Eleazer Parmly. The folloAving are its advantages, where it can be resorted to Avith safety : after the removal of the pressure, the teeth almost immediately come together, having no space to injure their beauty; what is of still greater importance, the dentine around the external surface of the fill- ing is not exposed to the action of the secretions of the mouth, or other agents capable of exerting upon it a deleterious action. On the other hand, some are of opinion that Avhen the teeth come together again a lodgment is afforded to corrosive agents, upon the presence of Avhich the disease Avas, in the first instance, produced, and Avhich would soon cause a recurrence of it. In replying to this objection, it is only neces- sary to observe, that the parts of teeth first attacked by caries were the points in contact with each other, Avhere the enamel may be sup- posed to have sustained some injury by pressure, thus rendering them more vulnerable at these points to the action of the causes that pro- duced the disease. By properly replacing the diseased parts with gold, the external surfaces of the fillings will be the only parts that come in contact with each other; and if of gold will not be liable to injury from the above-mentioned mechanical causes. The enamel around the 312 FILLING TEETH. fillings, if proper attention to cleanliness be observed, is not so liable to be acted on by chemical agents as the dentine which the file would expose. But teeth cannot always with impunity be separated by pressure; it can only be done with safety in certain cases. As a general rule, the writer is of the opinion that it ought not to be attempted after the thirtieth or fortieth year of age, though it may sometimes be done with safety at even a later period. The diseased action, excited for the time, in the sockets of the teeth, does not so readily subside at a later age; and it has in some instances been known to result in the loosening and ultimate loss of the organs. In one case which came under the observa- tion of the author, the inflammation extended to the lining membranes of the pulp, causing their disorganization, and the consequent death of the tooth. The pressure ought never to be too actively exerted; it should be gradual and constant. From four to seven days are usually required for the separation of tAvo teeth sufficiently for the removal of the de- cayed part and the introduction of a filling. After they have been separated in this way, they should be kept apart, without any increase of pressure, until the soreness in the sockets shall have subsided, before any further steps are taken in the operation. Only two teeth should be separated in the front part of the mouth, in the same jaw, at the same time. The pressure is usually made by introducing, between the crowns of two teeth, a thin wedge of soft wood, a piece of India-rubber, tape, a little raw cotton or ligatures, replacing the first-named substances every day or two Avith thicker pieces. The writer prefers India-rubber to any other substance he has employed for the purpose; but the object may be readily attained with other substances. While many prefer gradual pressure in separating teeth, there are others, who, on account of economy of time, consider it better for the separation to be made at once, and not prolonged through several days. It is also urged that the patient suffers less, and that there is also less danger to the teeth, in rapid separation than where this process is gradual. The degree of pressure, and the method by Avhich the separation is to be accomplished, should, hoAvever, be determined by the susceptibility of the parts to inflammation. The operation of rapidly separating the teeth consists in the use of two wedges of fine grained wood, either orange or box AA7ood. The first wedge is forced betAA'een the necks of the teeth, care being taken not to lacerate the gum, while the second wedge, which tapers more than the first, is inserted between the points of the teeth, the Avedges being driven alternately by mallet for,ce, until sufficient space is obtained, when the second wedge is removed. Very great care FILLING TEETH. 313 should be exercised in driving the second wedge between the points of the teeth, on account of the force exerted by it. This description ap- plies to the front teeth, as it is not advisable to attempt the separation of the molar teeth in this manner. But Avhether the teeth be separated with a file or by pressure, the space should be sufficiently wide to enable the dentist to operate with ease, otherwise, it Avill be impossible to remove the caries and fill the teeth in a proper manner. Fig. 84. Protecting Cavities from Moisture.—The first step in this operation is to wipe the mucous membrane, covering the parts about the tooth to be filled, perfectly dry, as well as the mouth of the duct of the nearest salivary gland, from Avhich saliva may flow in such a manner as to interfere with the oper- ation of filling the cavity. Over the mouth of the duct, a roll of bibulous paper is placed, upon which rests one part of a napkin, which is so arranged about the tooth as to prevent the mucus se- cretions from reaching the cavity. The napkin is held in place by the thumb and fingers of the left hand. The remaining portion of the napkin can be used to prevent the breath from coming in contact with the material used for filling, as Avell as the cavity. When this is accomplished, the cavity is dried, as hereafter described, and is then ready for the filling. Much more 314 FILLING TEETH. difficulty is met with in protecting cavities in the inferior teeth from moisture than in the case of the superior, and various appliances have been devised to overcome it. The common saliva pump (Fig. 84) is used to remove the saliva as it accumulates in the lower part of the mouth, and consists of a glass tube with an elastic bulb. Fig. 85 represents a very superior saliva pump. A, bottle or reservoir. C, clamp, furnished at its upper and lower ends with eight steel pins, E, F, to secure it to the upholstery of a chair, so that it cannot be detached by any accidental force. When used, the hard rubber mouth-tube, I, is held in the mouth by one hand of the patient, and the bulb, K, in the other. Whenever saliva accumu- lates, the patient presses the bulb, and the saliva Aoavs into the reser- voir. The reservoir is emptied by un- screwing its cap, B. The bulb is covered Avith soft leather. Its valves are of hard rubber, and operate well in any position. As they operate in the air only, they never clog or become deranged by contact with the saliva. The mouth tube is of hard rub- ber, and the apparatus requires no care beyond occasional Avashing. Fig. 86 represents Dibble's saliva pump, with the attachment of Dr. B. F. Arrington, Avhich acts also as a speculum, or tongue-holder. The object of this instrument is to facilitate the operation of filling teeth of the loAver jaw by keeping the mouth free from saliva, and as a means of holding the tongue aAvay from the teeth ; also, a means of 9445 FILLING TEETH. 315 Fig. 87. supporting the upper jaw, and so assisting the muscles which keep the mouth open, the application of Avhich will be readily understood from the illustration. There are tAVO mouth-pieces, one for the right side, and one for the left side of the mouth. Various appliances are also in use for keeping the jaws apart, pressing away the cheek, and holding down the tongue. Fig. 87 represents an instrument of this kind, invented by C. C. Thomas, of Louisi- ana. It consists of two grooved plates to admit the molar teeth, which may be sepa- rated or brought to- gether by a screw Avorking in a cylinder. Around the cylinder are two collars, which can be tightened by set screws ; to the lower is soldered a rod on which moves a ring holding a hand-shaped tongue- holder ; to the upper is attached a highly polished oval concave plate, connected with the shaft by a ball and socket-joint; the shaft itself is capable of extension by a rachet movement. The instru- ment is ingeniously contrived, so that its several parts can be moved in any required direction and extent. Its application is obvious; it opens the mouth, keeps the tongue and cheek out of the way, and the oval mirror throws light on the cavity. Fig. 88 represents an excellent tongue and duct compressor — Hawes instrument modified by Dr. P. T. Smith. By its use, the tongue may be clamped doAvn in place and kept in position as long as desired. The sublingual and submaxillary ducts may be very effectually closed by placing upon them rolls or pads of bibulous or tissue paper before applying the compress; a pad of paper or a napkin should be placed on the tongue before adjusting the instrument. The use of it is a relief to patients rather than a discomfort, holding Fig. 88. 316 FILLING TEETH. the tongue entirely out of the Avay during an operation, without re- quiring a constant effort on their part. For one of the most simple, yet effective appliances for controlling the flow of saliva, and protecting cavities from moisture, Ave are in- debted to Dr. S. C. Barnum. It consists of nothing more than a thin sheet of India-rubber, of good quality, that it may possess sufficient strength and not tear easily, and of a thickness double that of letter paper. Some distance from the edge of the sheet, which is from four to eight inches square, one, two, or more holes are made, through which the crowns of the teeth are passed, when it is applied to the mouth. The holes made in the rubber should be about one-tenth smaller in diameter than the necks of the teeth they are to embrace. It is better in all cases to make several of these holes in the sheet in order to include within the coffer-dam, formed when the sheet is in position, the croAvns of the teeth adjoining the one in Avhich the cavity to be filled is situated. When the crowns of the teeth approximate closely, the holes should be made about one-eighth of an inch apart; if some space exists betAveen the crowns, the holes may be made at a greater distance from each other. These holes may be formed in the rubber by means of a small chisel-edged punch, or by burning with a heated instrument. The rubber, thus prepared, is carried between the teeth by either a thin, flat burnisher, or, Avhich is better, by waxed floss silk, and the margins of the holes pressed gently under the free edges of the gums in the direction of the roots of the teeth. In some cases it may be necessary to secure these margins to the necks of the teeth by means of Avaxed floss silk tied around them. Several other simple appliances are in use to protect cavities from moisture, such as Avooden wedges forced between the necks of the teeth, and Avaxed cord surrounding the tooth in Avhich the cavity is situated, and passing to an adjoining tooth ; also a band of rubber cut from tubing, which is placed high up on the neck of the tooth and then carried around an adjoining one. Two of these bands, acting in opposite directions, answer better than a single one, and in many cases effectually protect the cavity from moisture. Drying Cavities.— After every particle of decomposed dentine has been removed, the cavity should be thoroughly cleansed before the filling is introduced. This may be done by first injecting tepid Avater into it Avith a properly constructed syringe, and afterward Aviping it dry Avith a small lock of raw cotton fixed upon the point of a probe or excavator; or the cavity may, in the first place, be Aviped with a little raw cotton moistened Avith Avater, and afterward with drv cotton. FILLING TEETH. 317 The application of the cotton should be followed by that of bibulous paper, made expressly for the purpose, and having a very loose, ab- sorbent texture, and folded for convenience in the form of a rope, from which the moistened end can be torn after each insertion. Tissue or bibulous paper absorbs moisture more readily than cotton. The ab- sorbing qualities of cotton, however, may be increased by boiling it for fifteen or twenty minutes in a tolerably strong alkaline solution; this done, it should be thoroughly AA'ashed and dried before using; or by saturating it in sulphuric ether to remove the natural oil. Several materials have been of late years used in drying cavities, such as pre- pared flax, fine and Avhite, with a long absorbent fibre, and prepared spunk. It is desirable that the cavity should be perfectly dry before the filling is introduced. INSTRUMENTS FOR INTRODUCING GOLD. For introducing and consolidating non-adhesive gold foil, a number of instruments are required, which should be sufficiently strong to resist any amount of pressure the dentist can safely exert in the opera- tion. They should have round or octagonal handles, large enough to prevent the liability of being broken and to enable him to grasp them firmly. Their points should vary in size, though none should be very large. Several should be straight, but for the most part they require to be curved — some very slightly, others forming with the shaft of the instrument an angle of ninety degrees. Fig. 89 represents a set of small pointed hand pluggers. For other forms, the reader is referred to the chapter on " Filling Individual Cavities," Fig. 89. j | j j i fl i i I J » « Milium Plugging instruments as received from the instrument makers have usually a temper which will not permit them to be bent. It will add, we think, greatly to the value of the instrument, if the practice of Dr. 318 FILLING TEETH. Maynard Avere more generally adopted. He gives to the extreme point a hard temper (straw color) to prevent it from Avearing; for a little distance, say one to three-quarters of an inch, a spring temper is given (purple or blue color) to insure strength when the shape is delicate ; the rest of the instrument is left soft, so as to admit of being bent (Avith pliers) in the direction best suited for that particular point in any given operation. Most of them should have a slim wedge-shape; some, however, both of the straight and curved instruments, should have blunt serrated points, and a few should have highly polished oval points, for finishing the surface of fillings. Formerly, most dentists employed for intro- ducing and consolidating the gold simple blunt-pointed pluggers; but it is impossible with such instruments to make a filling as firm and solid as it should be for the perfect preservation of a tooth, especially if the cavity is large. From one-fourth to one-half more gold can be introduced into a tolerably large cavity Avith a Avedge-pointed than with a blunt-pointed instrument. Fig. 90. FILLING TEETH. 319 The sides of the wedge-pointed pluggers should be left a little rough, for the purpose of preventing them from cutting the gold; and there should be two or three small notches filed across their edges. Wlien thus prepared, the gold can be more perfectly controlled and more readily conveyed to the bottom of the cavity than Avith smoother- edged instruments. The blunt-pointed instruments, or those used for condensing the extruding extremities of the folds of gold, should, as before stated, have serrated points, that the surface of the metal may be thoroughly consolidated. This general description will serve to convey a tolerably correct idea of the kind of instruments required for the operation; but no two dentists have their filling instruments precisely alike ; each has them constructed in such a Avay as he thinks will enable him to apply them most easily and efficiently to the various parts of a tooth Avhich may require filling. Instruments having serrated points are required for filling teeth with crystal or sponge gold, and Avith adhesive gold foil. Fig. 90 represents a number of small points suitable for using the adhesive forms of gold. For other forms of points, the reader is re- ferred to the illustrations representing the points of mallet pluggers. Fig. 91. Fig. 91 represents a pair of introducing or plugging pliers for taking up pieces of gold and placing them in the cavity. This instrument is indispensable in using adhesive gold foil, and also the non-adhesive in the form of cylinders ; for carrying cylinders to their proper position in the cavity, the points are not serrated as in the cut. MANNER OF PREPARING, INTRODUCING, AND CONSOLIDATING GOLD AND FINISHING THE SURFACE OF THE FILLING. Non-Adhesive Gold Foil.—The operator, being provided with the necessary instruments, should cut this form of gold, Avith a pair of scissors, into strips from half an inch to an inch Avide. Each of these should be loosely rolled or folded together lengthwise, and after the cavity has been properly cleansed and dried, the end of one should be introduced and carried to the bottom of the cavity, with a straight or curved wedge-pointed instrument; the roll on the outside should then be folded on the part first inserted. The folding should'be com- 320 FILLING TEETH. menced on one side of the cavity, and the inner end of each fold taken to the bottom, the outer extending nearly a twelfth or an eighth of an inch on the outside of the orifice ; thus, fold after fold is introduced, until no more can, in this manner, be forced into the cavity. Having proceeded thus far in the operation, the instrument should be forced- through the centre of the filling, and the gold firmly pressed against the walls of the cavity. The opening thus made should be filled in the manner as first described, and this time it should be packed in as tightly as possible. This done, the operator should endeavor to force a small wedge-pointed instrument in the centre of the filling, until he has tried every part of the plug; filling, as he proceeds, every opening Avhich he makes, and exerting, in the packing of the gold, all the pressure Avhich he can apply, Avithout endangering the tooth. If one roll or fold of gold is not enough, he should take another and another, until the cavity is thoroughly filled. When the Avails of a cavity are frail, it is the practice of some operators to introduce the gold rather loosely, and to depend upon surface con- densing to obtain the necessary solidity. But it is better to well condense every fold immediately after it is carried to its proper place in the cavity ; such condensing will often render the use of the Avedge- shaped instrument unnecessary. The advantage to be derived from introducing the gold in this man- ner is obvious. By extending the folds from the orifice to the bottom of the cavity, the liability of the gold to crumble and come out is effectually prevented; Avhile by introducing it with a Avedge-pointed instrument, it may be carried into all the depressions of the Avails of the cavity, and rendered altogether more solid than it could otherwise be made. The pliancy and adhesiveness of the gold may be increased by slightly Avarming in the flame of a spirit lamp, after it has been made into rolls or folds. After the cavity has been completely filled, every portion of the pro- jecting part of the gold must be thoroughly consolidated, before it is alloAved to become Avet, either with a small blunt-pointed instrument, straight or curved as may be most convenient; or, if the filling is in the approximal side of a tooth, it may be compressed with the angle of the point of the plugger, making the adjoining organ to a slight extent a kind of fulcrum for the instrument. After the filling has been thus consolidated, as long as it can be made to yield in the least to the pressure of the instrument, the protruding parts may be scraped or filed off, doAvn to the tooth, so as to form a smooth, uniform, gently swelling or perfectly flat surface. Fig. 99 represents a number of finishing files. If in this part of the operation any portion of the gold should crumble or be dislodged, which it will not do if it has been FILLING TEETH. 321 properly introduced and consolidated, the injury may be repaired by making in the part of the plug, where it has occurred, an opening, and filling it, or by the removal of the whole of the filling and the intro- duction of another. If any portions of the gold have been forced over the edge of the orifice of the cavity, they should be carefully removed, either Avith a file or sharp-pointed cutting instrument suited to the pur- pose. This precaution should never be neglected, especially Avhen the filling is in the approximal surface of a tooth, where a portion of the gold is very liable to be forced up or doAvn upon the neck, and under the gum. Cylinder Filling.—The method of filling cavities with non-adhesive gold foil in the form of cylinders is a favorite one with many opera- tors, and is in some cases preferable to that of the fold or rope, inas- much as the gold in the cylinder form can be more rapidly introduced and condensed. A common method of preparing these cylinders is to fold lengthwise, in the form of a ribbon, either the third, half, or Avhole of a leaf of No. 4 or 6 gold foil; the width of the ribbon determines the length of the cylinders. One end of this ribbon is then held between the thumb and index finger of the left hand and wound upon a three- or four-sided broach until the cylinder thus formed is of the size desired, when the remaining portion of ribbon is torn off. The cylinders should be a little longer than the cavity is deep, in order to alloAV for surface condensing. The density of the cylinders depends upon the firmness with which the ribbon is Avound upon the broach; by Avinding it loosely upon the broach soft cylinders are formed, to be placed in contact Avith the Avails of the cavity, Avhile the hard cylinders made by firmer Avinding are introduced inside of the soft, and form the centre of the filling. Different forms as well as siz.a of cylinders are necessary in every case, cone-shaped as well as the true cylindrical. The cone-shaped cylinders are useful Avhere there is an under-cutting, and also for completing the introduction of the gold. These cone-shaped cylinders are formed by winding the ribbon back from the point of the broach, Avhich should taper slightly in order that the cylinder Avhen completed may be easily detached. For placing the cylinders into their proper places in the cavity, the introducing pliers are necessary, which have smooth points bent at such an angle as will permit of their being used, when closed, as a condensing point. The cavity being prepared for the gold and properly protected from moisture, one of the soft cylinders is carried into it with the pliers and placed in such a position that one end rests on the bottom and the other protrudes from the orifice. Pressure in the direction of the wall 21 322 FILLING TEETH. against which the cylinder rests is then made with the closed points of the pliers, and afterward with a condensing instrument having either a smooth wedge-shaped point or, Avith what is better, a serrated point, such as are represented in Fig. 93. When the first cylinder introduced has been well condensed against one of the Avails of the cavity, others are introduced and condensed in succession until these walls are covered by the soft cylinders. The hard cylinders are then disposed round the cavity in the same manner as the soft ones, until it diminishes so much as to render it necessary to form a cavity in the centre of the gold already introduced, by means of a smooth wedge- shaped instrument, such as is represented in Fig. 92. The cavity Fig. 92. formed by this instrument is then filled with a small dense cylinder, and successive openings are thus made and filled until no more gold can be introduced, when the protruding ends of the cylinders are con- densed by pressure applied in the direction of the bottom of the cavity. The surface of the filling is then finished in the manner to be described hereafter. When the cavity is of considerable depth and small in diameter, or the bottom is uneven, pellets of gold may be introduced and condensed upon the bottom until the cavity is about one-third filled. By this method the gold is better adapted to the bottom of the cavity than by placing the ends of the cylinders upon an uneven surface. The surface condensing of cylinder fillings should be made with small-pointed condensing instruments, and any opening it is possible to make with them be filled with small d n n r? llll " Preparation of the Cylinders. It is seldom necessary that a cylinder should contain more than one-third of a sheet of No. 3 gold foil. Any number of small cylinders prepared by this method may be placed side by side, and condensed by lateral pressure more readily than the same 324 FILLING TEETH. quantity of gold could be, if formed into but one cylinder. Small cylinders can also be adapted to the walls of the cavity much better than long ones. The gold from which they are formed should be as foft and tough as it can be manufactured, and does not require to be reannealed either in the leaf ribbon or cylinder. In preparing the ribbon, a leaf of gold is cut into three pieces, each of which is rolled diagonally on a steel rod, the diameter of which should be the same as the depth of the cavity to be filled. The rod is withdraAvn from the cylinder by passing the thumb and forefinger gradually to the free end, and reversing the movement of the rod in Avinding the gold about it. The long cylinder thus formed, and held between the thumb and fore- finger, is noAV rolled, without being flattened previously, on a rod of a size necessary to give a proper length to the small cylinder it is desired to make. As soon as the cylinder is AvithdraAvn from the rod, it is pressed slightly between the thumb and forefinger in order to give it an oval form, and also to prevent its unfolding. To form smaller cylinders, the ribbon is cut into such lengths as are necessary to make the size desired. Some of the cylinders should be dense enough to per- mit of their being forced into their places Avhen the introduction of the gold is nearly completed. Dense cylinders may be made from the oval form by bending the sides together Avith the introducing pliers, or by the common method of folding the ribbon and Avinding it tightly on a broach. "Preparation of Cavity. The walls should be as nearly per- pendicular as possible, and without much under-cutting; retaining points are unnecessary. Slight grooves in opposite walls are sufficient to retain the filling. "Introducing the Cylinders. The cylinders, in using this method, are carried with the pliers to a point in the cavity farthest from the operator, and placed in such a manner as will enable him to apply the pressure against the free ends ; the opposite ends of the cylinders being in contact Avith the posterior wall of the cavity." "The pressure appl'ed during the introduction of the gold should always, Avhen prac- ticable, be in a direction from the operator." "After introducing a sufficient quantity of gold to fill a third or half of the cavity, before making lateral pressure care should be taken to adapt the gold Avell to the bottom." "Lateral pressure is then made and more gold intro- duced until the cavity is filled; the last cylinder used being a dense one." " The gold should be so evenly and solidly introduced that there will be no necessity for using the Avedge-shaped instrument; should the use of this instrument, however, be necessary, the opening made by it may be filled with one of the dense cylinders or with the strip." " After all the gold necessary is introduced, the surface of the FILLING TEETH. con fillino- should be condensed with a large and deeply serrated instru- ment, and followed by one of smaller size and finer serrations." Pelkfs.—Another form in Avhich non-adhesive gold foil is used is that of pellets, Avhich are formed by lightly rolling a portion of a sheet between the thumb and fingers. They are made of different sizes, and when placed in a cavity are Avelded together by means of pointed or serrated instruments. It is necessary that the first pellets introduced should be securely anchored, in order that the successive ones may be built upon them ; these last should be small enough to alloAv the welding instrument to pass through them to the gold beneath. ADHESIVE GOLD FOIL. In manipulating Avith adhesive foil, a preliminary step in the opera- tion is to attend to the quality of the gold. It must possess sufficient adhesiveness to cohere under moderate pressure; and as this property deteriorates on the exposure of foil to the atmosphere, it is often neces- sary to restore it by the application of heat, as the welding principle, and not mechanical force, is relied upon. To accomplish this, the gold, either in the sheet, roll, or pellet form, is subjected to the flame of an alcohol lamp until it becomes a bright red. A wire-gauze frame is very convenient for reannealing the sheet, and.a mica plate or plati- num pan for the pellets. Many prefer to pass the roll and pellets directly through the flame at the moment they are being carried to the cavity with the introducing pliers. Another method is to boil the gold for a few minutes in a solution composed of forty drops of sulphuric acid and two gills of rain-water. This diluted acid removes all extraneous matter from the surface of the gold, which soon drie*, and is found to be very adhesive. There are a number of methods by Avhich this form of gold foil is pre- pared for introduction into the cavity. One consists in tearing frag- ments from a sheet which has previously been annealed on wire-gauze, and condensing a single thickness at a time with a fine serrated point. Another method consists in lightly rolling up the whole or part of a sheet in the form of a rope, and cutting this up into pellets of different sizes. In forming the pellets, the sheet should be very lightly rolled up between the thumb and fingers, or, what is better, lightly folded by means of a spatula and chamois skin. Some, instead of forming pellets, prefer to introduce this quality of gold in a long rope, Avhich is annealed by holding it in the centre with the pliers and rapidly passing it through the flame. When the gold is ready to introduce, and the cavity is carefully dried and protected against moisture —absolute dryness being very essential in the use of all the adhesive forms of gold —the first pellet, or the end of the rope, 326 FILLING TEETH. when this form is used, is carried from the flame to a retaining point in the cavity, where it is securely anchored by being thoroughly con- solidated by means of instruments having fine serrated points. As soon as the retaining points are solidly filled, the gold is built up from these over the bottom and sides of the cavity, care being taken to condense it well against the walls as it approaches the orifice. Every pellet must be consolidated as it is introduced, and the gold built up higher against the walls of the cavity than in the centre, until the orifice is reached, Avhen the depression left in the centre can be filled up. Very lightly rolled pellets should be applied to the walls of the cavity; for if the pellets be formed from a tightly-rolled rope, they have a tendency to clog, and cannot be consolidated to such a degree as is necessary to give solidity to the filling. Fig. 98 repre- sents the forms of instruments for introducing and consolidating adhe- sive gold foil. Heavy Foil.—A number of years ago, attention was directed by Dr. Robert Arthur to the use of the heavy numbars of gold' foil for filling teeth; and of late the interest in this form of gold has revived to such a degree that very many iioav aclvTocate its claims, among the number Dr. W. H. Atkinson, to Avhom the credit is due of again bringing it into notice. Nos. 15, 20, 30, 60,120, and even higher numbers, are in use. Nos. 15 and 20 can be consolidated by hand force, if such is desired, while the heavier numbers require mallet force. The method of manipu-' latingthis foil is to cut it—without allowing it to come in contact with the fingers — into pieces varying from one-fourth to three-fourths of an inch square, or into strips of a proper width and length to suit the cavity to be filled. The gold is then annealed by heating each piece or strip, held by the pliers in ths flame of an alcohol lamp, to a red beat. For filling the front teeth the strip is preferable, condensing each layer across the entire surface of the cavity, and folding the strip upon itself. Retaining points are solidly filled, and the gold built from one to the other, presenting as plane a surface as possible, and not alloAving the foil to become crumpled or folded irregularly upon Itself. For filling the posterior teeth the small pieces are preferable, introduced, like the strip, with the pliers, and each one thoroughly consolidated. The gold should be carefully condensed at and over the margins of the cavity layer by layer. The manufacture of these heavy foils by rolling instead of beating, is said to render them softer and more adhesive. Fig. 98 represents the instruments necessary in manipulating the heavy foils. Dr. W. H. Morgan, after considerable experience Avith this heavy foil, believes it to possess the following advantages over light foil: It FILLING TEETH. 327 is softer, and does not harden so readily under the instrument; there is less danger of breaking thin Avails in using it; it is more easily han- dled and controlled with the instrument; it is much more adhesive; it finishes up Avhen welded better than any other form of gold. CRYSTAL OR SPONGE GOLD. In the use of crystal or sponge gold, a different method of procedure is required from that employed with foil. The chief difference between the instruments employed for introduc- ing and consolidating crystal gold in the cavity of a tooth, and those used for gold foil, consists mainly in having the working extremity blunt, varying in diameter from a line to almost a mere point, with shallow serrations upon the surface. Fig. 94 represents a set of instruments well adapted for the manipu- lation of crystal gold. Fig. 94. In filling teeth with crystal gold, the cavity is prepared in the same manner as when leaf gold is employed. This done, the gold is cut, or, rather, torn from the block with the point of an instrument, into small pieces, varying in size according to the dimensions of the cavity and the particular stage of the operation in which it is to be used. It being important that the crystals or particles composing the mass should be as little separated or displaced as possible, before the piece is carried to its place in the tooth, it should be used in pellets as large as can be introduced into the cavity without crumbling. The gold being divided into pieces of the proper size, the cavity is washed, and then wiped dry with prepared cotton, or flax and bibu- lous paper; a piece of gold, as large as the orifice of the cavity will receive, is taken up with suitable pliers, or one of the sharp-pointed instruments, as may be most convenient. The spongy mass readily adheres to the serrated surface of the working extremity, when pressed gently upon it, and with this it may. °9ft FILLING TEETH. in most cases, be carried to the bottom of the cavity. Every part must now be thoroughly consolidated, first Avith a large, and next with a smaller, and lastly with a very delicately-pointed instrument, so bent that it may be readily applied to all the depressions and inequalities of the walls and floor of the cavity; for unless the gold is made abso- lutely solid in these places, as Avell as throughout all the parts of the filling, the success of the operation will be more or less uncertain. Thus, piece after piece is applied, consolidating each one as the opera- tion progresses, until the gold protrudes sufficiently from the orifice of the cavity to admit of a good finish, leaving the surface flush with that of the tooth. If, during any part of the operation, the smaller pointed instruments can be forced between the gold and the Avails of the cavity, such open- ing or openings should be filled with smaller masses of the material before another large piece is introduced. This precaution ought never to be neglected; for should any soft places exist after the completion of the operation, the filling will be likely to absorb moisture, and ulti* mately to crumble and come out. It is also indispensably necessary that the gold, during its introduction into the tooth, be kept absolutely free from moisture, as this destroys the adhesive or Avelding property of the crystals. The gold having been introduced and consolidated as directed, the exposed surface is scraped or filed down to a level with the orifice of the cavity, then made smooth by rubbing it Avith Arkansas stone or with finely-powdered pumice, and burnished or polished with .crocus, in the manner as described when gold foil is used. In finishing a filling made with these preparations of gold, the ope- rator should see that there are no thin overlapping portions upon the teeth outside of the orifice of the cavity. They are liable, in biting hard substances, or in ordinary mastication, to be broken off, leaving a depression for the lodgment of extraneous matter and clammy secre- tions. Sooner or later this will give rise to a softening of the dentine thus exposed, Avhich, if it does not cause the filling to loosen, will ulti- mately render its removal and replacement necessary. In short, the precautions necessary to be observed in making a filling with gold foil are equally necessary Avhen the operation is made with either of the preparations noAV under consideration. Mallet Force in Consolidating Gold. — Some ten years ago, Dr. W. H. Atkinson introduced a method of consolidating gold by means of mallet force, which has now become a favorite one with many of the best operators in the profession. He claims for this method the fol- lowing advantages over hand pressure: A more perfect condensation of the gold and a more thorough welding than can be made by hand FILLING TEETH. -29 pressure; that the gold will be anchored in its position Avith much more facility ; that the instrument always acts under the mallet upon the designed point, does not slip from its position, and, consequently, there is no liability of abrading or Avouuding the soft parts; that mal- let force is not more unpleasant to the patient than the ordinary method of condensing; and that it is far less fatiguing than hand pressure in protracted operations. That mallet force is an effective method of condensing the adhesive forms of gold,'there can be no question. Mallets of almost every description are used, such as Avood, lead, tin, copper, brass, steel, ivory, and vulcanized rubber. Heavy lead and tin mallets, weighing from four and a half to six and a half, and even eight ounces, are preferred by many of the advo- cates of this method. In using the hand mallet, which is represented in Fig. 95, the aid of an assistant is necessary, who taps the end of the plugger squarely with sharp, springing strokes, while the principal ope- rator directs its condensing point over the gold as it is introduced into the cavity. With instruments called automatic mallet pluggers — Fig. 96 represents Siioav and LeAvis's, and Fig. 97, Salmon's—the aid of an assistant is unnecessary. Both of these forms operate by the action of a spiral spring. Fig. 98 represents an excellent set of mallet pluggers designed by Dr. C. R. Butler. Finishing the Surface of the Filling.—After having thoroughly consolidated the surface of the filling, finishing files, such as are represented in Fig. 99, are used to remove the protruding portions of gold, and to form a smooth, uniform surface, free from the slightest indentations which -=^= ==: SCS P abw =^=^ jj^^i ^&£m Fig. 97. FILLING TEETH. may afford lodgment to extraneous matter. This is a point never to be lost sight of; for, however excellent the filling may be in other respects, if the surface is not smooth, uni- form, and flush with the orifice of the cavity, the object in- tended to be accomplished by it will be partially if not Avholly defeated. It is better, hoAvever, to file off but a portion of the pro- truding gold at first, and then to burnish, condense, and to file Fig. 98. a second time, with a fine file, all it is necessary to remove. After each filing, and before applying the burnisher, the sur- face should be cleansed of all loose pieces of gold. After a second burnishing, the Arkansas, Superior, or Scotch stone, or finely-poAvdered pumice may be applied to the surface to remove all the file scratches and other asperities. For a filling in the approximal surface of a tooth, the stone may be shaped like a pinion-file ; it should be frequently dipped in Avater, and when its pores become filled with gold, the surface may be ground off by rubbing it on a corundum slab. If the filling is finished Avith pumice, it may be applied Avith floss silk or tape moistened with Avater, by drawing it backward and for- ward across the surface of the filling. Fig. 100 represents an excellent file-carrier, contrived by Dr. Forbes, for files for finishing fillings on the approximal sur- faces of the front teeth, and Fig. 101, a tape-carrier. If the filling is in the grinding, buccal, or palatine surface of a molar or bicuspid, a long piece of the stone having a small, triangular, and slightly oval point may be used ; if FILLING TEETH. Fig. 99. 001 Oul Fig. 100. ��.C 966 32 FILLING TEETH. poAvdered pumice-stone be employed,, it may be used on the point of a similarly shaped piece of soft wood, "previously softened in Avater. After all the asperities have been cut doAvn, the surface should be washed until every particle of grit is removed. This done, it may be polished with a suitable burnisher, dipped from time to time in a solution of pure Castile soap, until the filling is rendered as brilliant as a mirror. Fig. 102 represents various forms of burnishers. Fig. 102. Having proceeded thus far, the surface may be again washed, and the operation completed by rubbing it from three to six minutes with dry floss silk. Rouge or rotten-stone applied to the surface on tape, or finely-powdered silex or pumice-stone on a piece of orange-wood, after it is prepared by the method just described, will remove the bright metallic lustre—when this is objectionable on account of the exposure of the filling — and leave a fine finish. Holly strips, in the form of thin shavings, ansAver admirably for applying levigated pumice, rouge, etc., in the polishing process. Non-Conductors.— When the caries has penetrated nearly to the pulp-cavity, the presence of a gold or any other metallic filling is sometimes productive of considerable pain and irritation, especially when hot or cold fluids are taken into the mouth, or during the inspi- ration of cold air. In some cases, inflammation and suppuration of the lining membrane and pulp supervenes. To prevent these dis- agreeable results, a variety of means have been proposed. Dr. Solyman Brown recommends placing asbestos, this being a non-con- ductor of caloric, on the bottom of the cavity previously to the intro- duction of the gold. The author prefers a thin layer of gutta-percha, Avhich may be used in the form of a thick solution prepared with chloroform, or a layer of thin gutta-percha cloth may be placed at once in the bottom of the cavity. When the solution is used, a drop FILLING TEETH. 333 may be placed in the cavity, and a sufficient time allowed for the chloroform to evaporate, before introducing the filling. A thin layer of "Hill's stopping," of Avhich gutta-percha forms the principal in- gredient, may be used with equal advantage. As a non-conductor, os-artificiel, or oxychloride of zinc, has no superior. The time required by an expert operator to fill a tooth Avell may be said to vary from thirty minutes to two hours and a half, according to the size, shape, and situation of the cavity, and in some cases a much longer time will be required. The author has found it necessary in filling some cavities, especially Avhen the restoration of a large portion of the croAvn was called for, to bestow as many as six hours' constant labor upon the operation. Less time and skill are usually required to fill a cavity in the grinding than in the approximal surface of a tooth; but the operation in either place, to be beneficial to the patient, must be performed in the most thorough manner. The dentist who does not feel the importance of making all his operations as perfect as possible, should never be intrusted with the management of these im- portant organs. Want of attention to two points in the consolidation of a filling often causes the ultimate failure of operations in all other respects well performed. First, by not making sufficient lateral com- pression whilst introducing the gold, the surface is apt to be more solid than the interior. Consequently the filling may drop out for want of a firm contact against the sides; or, if retained, it is apt on grinding surfaces to be pressed inAvard, leaving a space around the orifice for the penetration of fluids. Second, want of care in condens- ing around the edges of the filling will, by the crumbling away or scaling off of portions of the gold, expose the edges of the cavity to decay. In every part of the operation, the dentist should so guard his in- struments as to prevent them from slipping, which he will usually be better able to do by standing a little to the right and behind his patient than in any other position. In filling the lower teeth he should stand several inches higher than while filling the upper, and for this purpose he should have a stool or movable platform on Avhich to stand. When it can be done, he should grasp the tooth Avith the thumb and forefinger of his left hand, not only to prevent it from being moved by the pressure he applies, but also to catch the point of the instrument in case it should slip; if he is always careful to press in a direction toward the orifice of the cavity, this need not happen ; nevertheless, he should always take the precaution to guard against possible accident. When he cannot shield the mouth Avith the thumb and finger of his left hand, he should let the thumb or one of the 334 FILLING TEETH. fingers of his right rest either upon the tooth he is operating on or upon some other. For the special application and modification of these general direc- tions, the reader is referred to the filling of individual cavities in teeth. FILLING INDIVIDUAL CAVITIES IN TEETH. To describe the method of filling each individual cavity in every locality in which a tooth is liable to be attacked by caries would be unnecessarily tedious. But, as this is one of the most important, and, at the same time, one of the most difficult operations in dental surgery, it may be well to enter a little more into detail upon the subject than Ave have as yet done. In doing this, the writer will confine himself, for the most part, to the manner of filling a cavity in each of the fol- lowing localities, which are the parts of teeth most liable to caries. First. In the approximal and labial surfaces of the superior in- cisors and cuspids, and the palatine surfaces of the incisors; the ante- rior surfaces of the cuspids and the posterior surfaces of cuspids and incisors being rarely attacked by caries. Second. In the grinding, approximal, buccal, and palatine surfaces of the molars and bicuspids of the upper jaw. Third. In the approximal surfaces of the inferior incisors and cus- pids. Fourth. In the grinding, approximal, and buccal surfaces of the molars and bicuspids of the lower jaw. Other parts of the teeth sometimes become the seat of caries, but the foregoing are the localities most liable to be attacked by the disease. FILLING THE SUPERIOR INCISORS AND CUSPIDS. I. With. Non-Adhesive Gold Foil.—In describing the manner of intro- ducing a filling in one of the first-named teeth, we shall commence Avith the right approximal surface of the left central incisor. The direc- tions we propose giving for the performance of the operation here, will be applicable, with a feAv exceptions, to the same surface, on all the upper incisors. As a general rule, the gold should be introduced from behind the teeth forward and upward, and for the following reasons: 1. When the aperture between the teeth has been formed with a file, it should, when the circumstances of the case will permit, and for reasons stated in another place, be made wider behind than before; consequently, the diseased part can be most easily approached from this direction. 2. The gold, in the majority of cases, can be more conveniently introduced from the palatine side, and the force required for condensing it can be more advantageously applied. FILLING TEETH. 335 The exceptions to the above rule are, when the approximal side of the tooth is turned slightly forward toward the lip, and Avhen the caries is situated nearer the labial than the palatine angle ; also, when the teeth, instead of occupying a vertical position in the alveolar border, or projecting slightly, as they usually do, incline backward toAvard the roof of the mouth. It sometimes happens, too, when they are sepa- rated by pressure, that the diseased part can be most conveniently reached from before. The instrument Avhich the writer has found best adapted for the introduction of the gold into a cavity in the right approximal surface of an incisor or cuspid tooth is represented in Fig. 103. The width and length, as Avell as the curvature or angle of the point, should vary according to the size of the cavity and the width of the space between the teeth. Fig. 103. The stem of the instrument as well as the shank should be strong enough to sustain any amount of pressure which it may be necessary to apply in forcing the folds of gold tightly against each other. The point should be wedge-shape, and the extremity serrated. The ornamental beading and „ 1 • ! T Fl«- l04. collar are objected to by some operators as apt to wound the mouth. The shaft, ferule and handle may be made continu- ously tapering, as in Fig. 104. The decay having been removed, the cavity, properly shaped, cleansed, dried, and protected, is ready for the reception of the gold. The patient should be seated in a chair sufficiently high to bring the head on a level with the breast of the operator, and resting on the head-piece of the chair, with the face upward. The operator, standing upon the right side, should support the patient's head firmly with his left arm during the operation, while with the thumb and forefinger of the same hand the strip or roll of gold is held, and one end placed in a proper position to be introduced into the cavity. The middle finger of the same hand ought to rest on the end of a tooth to the left of the one on which the operation is being performed, while with the little finger the lower lip may be gently depressed. During the introduction of the gold, the instrument should be held (Fig. 105) in the right hand of the operator, and grasped with sufficient firmness to prevent it from slipping or rotating. 336 FILLING TEETH. In introducing the gold, the first fold should be applied against the upper Avail of the cavity, Fig. 105. that the pressure may always be exerted in a direction to- ward the extremity of the root, applying each additional fold as closely to the preced- ing one as possible. The folds should also, in their introduc- tion, be applied as closely to the labial and palatine walls of the cavity as possible, but always directing the pressure, when these are thin and brittle, in the direction of the axis of the root. When the lower part of the cavity is very narrow, as is often the case, especially where it extends nearly to the labial angle of the tooth, it is often necessary to change the instrument for one having a smaller point. To carry a fold of gold to the bottom of a cavity, upon the point of the instrument, Avithout breaking or cutting it, requires some tact. The point should never be carried directly toward the bottom : on entering the orifice, it should be inclined toward the wall of the cavity opposite the one against which the folds are first laid. Equally as much tact is required to prevent displacing the gold before a sufficient quantity has been introduced to procure support for it from the surrounding Avails: which is an accident particularly apt to occur witli young practitioners, when the cavity is superficial and has a large orifice. To prevent this, the folds of gold should be long enough to project some distance from the orifice, that they may receive support from the adjoining tooth, and from the thumb and forefinger of the left hand of the operator, until the operation has reached that stage Avhen sufficient stability shall have been obtained from the walls of the cavity. There are cases in which an instrument like the one represented in Fig. 106 can be very advantageously em- ployed in the introduction of the gold ; but in the majority of cases the instrument represented in Fig. 103 will be found more convenient. After having filled the cavity so thoroughly that a small wedge- pointed instrument cannot be made to penetrate the gold at any point, the extruding portion of the filling should be consolidated; beginning Avith the portions overlapping the loAver part of the tooth and the edge of the posterior wall. These should be carefully and firmly pressed Fig. 106. FILLING TEETH. 3o7 toward the cavity, with an instrument like the one represented in Fig, 107. This done, it may be firmly applied to every part of the surface of the filling, continuing the pressure as long as the point of the instru- ment can be made to indent the gold. When the space between the teeth is very narrow, an instrument shaped as in Fig. 108 may be used. The operator should be provided with tAvo or three instruments like each of the tAvo last, varying in the size, length, and curvature of their points. Fig. 107. Fig. 108. Fig. 109. During the process of consolidating the gold, the tooth should be firmly grasped between the thumb and forefinger of the left hand ; this prevents it from being pressed too forcibly against the opposite side of the socket, Avhile, at the same time, the end of the forefinger, by being placed above the instrument, assists in directing its point, and serves to keep it from slipping. When the labial and palatine Avails of the cavity are very thin, great care is necessary to prevent fracturing them, in introducing and consolidating the gold. The consolidation should be commenced around the edges, and the pressure applied to- ward the centre of the cavity. It sometimes happens that the caries extends forward to the labial angle of the tooth, and upAvard, at the same time, under the edge of the gum. Great difficulty is often felt in thoroughly filling this por- tion of the cavity, and it cannot always be done from behind the tooth. In this case, after having filled the cavity in the manner as already described, the operator may, standing on the left side of the patient, and with an instrument having a wedge-shaped point (Fig. 109), make as large an opening as pos- sible in the gold. This done, he may grasp the left late- ral incisor, or cus- pid tooth, with the thumb and middle finger of his left hand, elevating the upper lip with the forefinger of the same; then,with the instrument held as 22 Fig. 110. 338 FILLING TEETH. in Fig. 110, he may proceed to introduce the gold, filling the upper part of the opening first. After introducing fold after fold, until it is completely and compactly filled, the extruding portion should be con- solidated Avith a similarly shaped instrument, having a round serrated point, or the one represented in Fig. 108. The size of the roll of gold must be varied to suit the size of the cavity, though it should seldom have in it more than a fourth of a leaf of No. 4. If more than this be employed at one time, it will bo difficult to apply the folds sufficiently near each other. When the teeth have been separated by pressure, or when the aperture is as Avide anteriorly as posteriorly, the gold may be introduced from either side as is most convenient; but, Avhen introduced from before, it may be done in the manner as just described, the operator standing on the left side of his patient, and using such instruments as he finds best adapted (Fig, 103 or 109). The gold having been introduced and con- densed, the surface of the filling is to be finished in the manner already described. The method of filling the right central incisor in the left approximal surface is so very similar to that of filling the left in the right side, that it Avill not be necessary to enter so minutely into detail. In this as in the other case, the gold, as a general rule, should be introduced from behind the tooth, forward and upward ; but if introduced from the front, the operator should still stand on the right side of the patient. The head should have the same elevation, and inclination backward ; but the face should be turned more toAvard the operator to give him a better view of the cavity in the tooth, and to enable him to reach it more readily Avith the instrument. The cavity being formed, cleansed and dried, the operator may pro- ceed to introduce the gold as already directed, Avith an instrument like the one represented in Fig. 103. In many cases, however, he will require one having a ""*- somewhat longer point, and curved at nearly a right angle with the stem. The instrument should be held some- what differently in the hand (Fig. Ill a, and grasped firmly with the thumb and fore and middle finger, so as to prevent it from rotating. The head should be securely confined Avith the left arm, the upper Jin Fig. 111. FILLING TEETH. 339 raised Avith the left thumb, pressing it at the same time firmly against the anterior surface of the tooth. The middle or fore finger of the same hand may be placed against the gum just inside the tooth, to direct the application of the point of the instrument, prevent the liability of its slipping, and control the free end of the roll of foil. The lower lip may be depressed either with the middle joint of this, or with one of the other fingers. After having placed one end of the gold in the cavity, fold after fold should be introduced until it is compactly filled ; except in those cases where the lower part is very small, when a smaller-pointed in- strument should be employed for the completion of the operation; and indeed for the introduction of all the gold, if the cavity is no; large or the aperture between the teeth very narroAV. For consolidating the extruding gold, the instrument represented in Fig. 107 will, in many cases, be all that is required. But the one repre- sented in Fig. 112 can sometimes be used very advantageously; and Fig. 112. Fig. 113. the one in Fig. 113 Avill be found a useful condenser for the right as Avell as the left approximal surface of an incisor, or cuspid tooth ; and both the last-mentioned instruments may often be used to great advantage on the approximal surfaces of other teeth. Some of the instruments employed in filling teeth with adhesive and crystal or sponge gold may also be advantageously employed in consolidating the ordinary gold in the approximal surfaces of the incisors and other teeth. In completing the operation, it is important that every particle of gold overlapping the orifice, and frequently extending under the free edge of the gum, should be removed before finishing the surface of the filling ; but the operator ought, at the same time, to avoid as much as possible Avounding the gum and dental periosteum. As the cavity frequently extends a little above the gum, great care is necessary to prevent wounding it; indeed, there are many cases in which it cannot be avoided, unless the point of the gum is pressed up between the teeth, by the introduction of a piece of raw cotton, band of rubber, or wedge of wood, a day or two before the operation of filling is performed. In filling an incisor, or cuspid tooth, on the labial surface, the ope- ration is often very simple and easv; but there are many cases in which it is both difficult and tedious. Th > head of the patient should rest with the face upward, as already described, and sustained in the same 340 FILLING TEETH. Fig. 114. way with the left arm of the operator; while, Avith the thumb of the left hand placed on the gum above the tooth, the upper lip should be elevated. The forefinger should be pressed firmly against the palatine surface of the tooth, and the left side of the chin gently grasped with the other three fingers. Then, Avith an instru- ment (Fig. 114) having a wedge-shaped point, grasped Avith the right hand, as in Fig. Ill or 115, the operator should proceed to intro- duce the gold, standing at the right side of the patient, with the thumb of the right hand resting on a tooth to the left of the one he is about to fill, or against the cheek. He should com- mence by laying the first folds against the walls of the cavity nearest to him, and thus introduce fold after fold, until it is compactly filled. The Fig. 115. Fig. 116. S' extruding portion may be consolidated with a round or square-pointed instrument, or with a straight-pointed one as represented in Fig. 116. Great care is necessary to prevent the instrument from slipping and wounding the gums. After having partially consolidated the gold, the overlapping portion must be firmly pressed toward the centre of the cavity, and the point of the instrument repeatedly applied to every part of the sur- face of the filling, until it can no longer be made to yield to pressure. This done, the gold may be filed doAvn to the level of the tooth, smoothed with Ar- kansas stone, and burnished or polished. When the cavity is shallow and the orifice broad, the gold as it is introduced must be held in its place with the thumb of the left hand, until a sufficient quantity has been placed in the cavity to obtain for it the necessary support from the surrounding Avails. But in over- coming difficulties of this sort, the peculiar circumstances of the case can alone suggest the proper means to be employed by the operator. FILLING TEETH. 341 The decay sometimes extends entirely across the labial surface of the tooth, leaving, after its removal, a horizontal groove open at both ends. In this case the walls should be made rough, Avider at the bottom than at the opening, and the operation of filling commenced at one end, by applying the folds of foil alternately against the upper and lower wall, and consolidating them so thoroughly as to prevent the liability of their being displaced during any subsequent part of the operation. Successive folds are introduced in the same manner, each in close con- tact with the preceding series, until the groove is completely filled, applying the pressure during the whole of the operation against the two walls. In condensing the extruding gold, the operator should com- mence first at one end of the groove, then at the other, and afterward consolidate the whole surface of the filling. In finishing the operation, the same precaution, Avith regard to wounding the gum and dental periosteum, should be observed here as recommended for the approxi- mal surface of the tooth. Although it rarely happens that the palatine surfaces of the upper incisors are attacked by caries, yet the disease does sometimes develop itself there, in the indentations occasionally found a little below the free edge of the gum. The removal of the diseased part, the forma- tion of a cavity, and the introduction of a filling, can, in the majority of cases, be more easily accomplished in this than in any other part of an incisor tooth. Fig. 117. Fig. 118. The cavity being properly prepared for filling, the head should be placed as before directed, except that the chin may be a little more elevated, to enable the operator to obtain a more convenient view of the locality of his operation ; the thumb of the left hand may be placed on the labial surface of the tooth; and the forefinger on the gum immediately above the palatine surface. He should now, with a Avedge-pointed instrument, shaped as in Fig. 117, proceed to introduce the gold, applying the first fold against the palatine Avail or the palato- approximal angle of the cavity, as may be most convenient. Having filled the cavity, the extruding gold may be condensed with an instru- ment like the one represented in Fig. 118. Sometimes straight instruments, and at other times instruments curved at the points more than those represented in Figs. 117 and 118, can be more conveniently employed ; depending altogether upon the size of the mouth and the forward or backward deviation of the teeth 342 FILLING TEETH. from a vertical position. This is a matter, therefore, which the judg. ment of the operator must determine. II. With Adhesive Gold Foil. — For filling cavities in the approxi- mal surfaces cf the superior incisors and cuspidati, the most effectual means should be adopted to retain the filling. In some few cases it may not be possible to do more than form small under-cuttings at each approximal angle of the cavity, and another similar one at the cutting edge, which would be sufficient for the retention of a non-adhesive gold filling; but in the majority of cases, one of adhesive gold can be so securely anchored that the cervical Avail is perfectly protected, and a fracture at any point along the edges of the cavity will not dislodge the filling. To effect this, retaining points made by a small, square-edged drill, are necessary, Avhich can be formed in approximal surface cavities of the incisors and cuspidati, in that portion of the dentine near the labial surface where it unites with the cementum, and in the same posi- tion in the palatine surface. These retaining points can be made from the one-twentieth to the one-sixteenth of an inch in depth, and in addi- tion a small under-cutting on the Avail next to the cutting edge. In dri ling the retaining points in the cervical Avail near the labial and palatine surfaces, the drill should be directed in a line with the long axis of the root in order that the cavity made by it is sufficiently dis- tant from the pulp of the tooth. The cavity being properly formed, dried, and protected from all moisture, the gold foil, prepared in the manner before described, is carried into the cavity with the introducing pliers, or on the point of an instrument, and packed into the retaining points until these are solidly filled. The gold is then compactly built from one of these retaining points to the other, and over the floor of the cavity until a base is formed extending over the Avhole of the floor. From this base the gold is then built to the orifice; and during the entire process, it is packed a little higher about the Avails than in the centre, in order to obtain a more thorough contact. When the gold has reached the orifice, the centre is then built up, and the surface con- densed and finished as before described. Crystal gold is preferred by some for filling the retaining points and forming the base covering the floor of the cavity, on account of its retaining its position better than foil. This description of the method of introducing adhesive foil will apply to all cavities Avherever situated, and need not be repeated hereafter. For crystal gold the cavity may be formed in the same manner as for adhesive gold foil, although many depend upon under-cuttings instead of retaining points for its retention. FILLING TEETH. 343 As the method of introducing crystal gold into cavities has already been described, it is not necessary to say more concerning it. FILLING THE SUPERIOR MOLARS AND BICUSPIDS. I. With Non Adhesive Gold Foil. — In describing the manner of filling a cavity in each of the principal localities liable to be attacked by caries, in the above-mentioned teeth, the Avriter will begin with the grinding surface of the first molar on the right side. The directions given for filling a cavity here, will, with a few exceptions, be applicable to the introduction of a filling in the grinding surface of any of the upper molars or bicuspids. When the cavity is very deep, and its circumference not large, it is difficult, if not impossible, to make a filling sufficiently firm and solid in every part by the introduction of folds of gold long enough to extend from the bottom to the orifice. The operation, therefore, should be divided into two parts; two-thirds of the cavity should be first thoroughly filled with vertical folds, and afterward the remaining third in the same manner. In filling a molar or bicuspid on any of its surfaces, the head of the patient should, for the most part, occupy very nearly the same position, and have the same elevation as required for an operation on an incisor or cuspid. The cavity being prepared for the filling, and one end of the roll of foil placed in it, the tooth may be grasped with the thumb and forefinger of the left hand of the operator — the former placed on the buccal surface in such a manner as to press back the commissure of the lips, and the latter on the palatine surface; then fold after fold maybe introduced and forcibly pressed against the posterior wall until the cavity is filled. For this purpose an instrument may be used like the one represented in Fig. 114 or 117. If the former is used, it is to be held as shown in Fig. 111. The extruding portion should then be condensed with a straight instrument, as in Fig. 116, or curved plug- gers, Fig. 118 or 119, as may be most convenient. As a general rule, filling a cavity in the grinding surface of an upper molar or bicuspid is an exceedingly simple operation, requiring less skill than the introduction of a plug in any other locality in these teeth; but there are cases in which it is rendered very difficult; as, for example, when there are one or more fissures or carious depressions radiating from the main cavity. After the caries has been removed, Avhich is often a very tedious operation, it requires considerable time and skill to fill these thoroughly. When it is not properly done, as is too often the case, a recurrence of the disease will soon take place, and thus defeat the object for Avhich the operation Avas performed. The introduction of a filling in the grinding surface of the second 344 FILLING TEETH. Fig. 119. or third molar of a person having a very small mouth, is sometimes attended with great difficulty; in some cases it can only be done with an instrument having a point bent nearly at right angles Avith the stem, like the one repre- sented in Fig. 119; consequently the power re- quired for introducing and consolidating the gold is applied to great disadvantage. But the instrument represented in this cut is only in- tended for the first part of the operation of con- solidating the metal; for its completion, smaller points are required. In filling a cavity in the grinding surface of a first upper molar on the left side of the mouth, the thumb of the left hand may be placed against the left cuspid or first or second bicuspid, as may be most con- venient to the operator; while the forefinger is placed behind the point of the instrument, and at the same time made to push back the commissure of the lips. To obtain a good vieAV of the cavity in a second or third molar during the operation, the cheek should be pressed from the tooth with the forefinger of the left hand ; but this finger can seldom be carried far enough back on this side of the mouth to be placed behind the point of the instrument. During the intro- duction of gold, the ring finger and little finger of the right hand should be made to rest on the incisor teeth, while the instrument is grasped (Fig. Ill) with the thumb, middle and fore finger. In filling a cavity in the anterior approximal surface of a right superior molar or bicuspid, the operation may be commenced by placing the gold against the palatine Avail, and ending at the buccal. But before the process of condensing is commenced, every portion of the sur- face ought to be thoroughly tested with a wedge-pointed instrument, and Avherever the point can be forced into the gold, the cavity thus formed should be filled. The instrument employed for the introduction of the gold may be like the one represented in Fig. 114, but having a rather longer point, and grasped as in Fig. 111. For condens- ing the extruding portions, either or both of the instruments represented in Figs. 108 and 112 may be used, as also the one employed for the intro- duction of the gold ; and one shaped as Fig. 120. Fig. 121. FILLING TEETH. 345 in Fig. 120 may be sometimes used Avith great advantage. During this part of the operation, the instrument may be held as before, or as seen in Fig. 121, Avhich permits a much greater amount of force to be applied than Avhen held in any other manner. Nearly the same method and the same instruments are required for filling a corresponding cavity on the opposite side of the jaAV. When practicable, the forefinger of the left hand should be placed on the palatine surface of the tooth, and the thumb against the buccal sur- face, and in addition to the instruments recommended for the right side of the mouth, the one shown in Fig. 106 may be very conveniently employed to introduce the gold; also Fig. 108 or Fig. 122, in con- densing the surface of the filling. The writer finds this last particularly valuable in very FlG- 122, face of a superior bicuspid on either side of the mouth, can, in the majority of cases, be as easily filled as one in the anterior approximal surface. The position of the left hand is very nearly the same, and in the introduction of the gold, the first folds are placed against the palatine wall of the cavity. By commencing on this side, the operator is enabled to lay the folds more compactly than he could Avere he to commence at any other point. He also has a more perfect control over the instrument in this part of the opera- tion, and has a better view of the cavity during the introduction of the gold. For consolidating the filling, the instruments represented in Figs. 107, 108, and 113 are as well adapted to the purpose as any that can be employed. When the mouth of a patient is large, a filling can often be intro- duced with nearly as much ease in the posterior approximal surface of a first or even a second upper molar as in that of a bicuspid; but Avhen the mouth is small and the cheeks fleshy, it often becomes a difficult and perplexing operation, although the same method is used; yet, as it is absolutely necessary to the introduction of a good filling that the operator should see the cavity and witness every part of the operation, bis ingenuity is often taxed to the utmost in contriving the most suitable means to enable him'to do it. A number of instruments for drawing back the corner of the mouth have been invented; but the writer believes there are none so well suited to the purpose as the thumb or forefinger of the left hand of the operator. If the operator Avill accustom himself to the use of a small mouth-glass held in the left hand whilst operating, he will be spared many back-breaking efforts to keep in view fillings on posterior surfaces. It is necessary to become familiar with the apparently reverse motion of the instrument 346 FILLING TEETH. as seen in the glass; also to accustom the three fingers of the left hand to act independently of the thumb and forefinger. But one of the most careful and skilful operators of this or any other country, Dr. Maynard, assures us that he works from a reflected view in the glass with the same ease as where he has a direct view of the cavity, and obtains, in very many cases where he uses the glass, an accuracy of view which direct vision could not give him. Before dismissing this part of the subject, there is one point to which the attention of the young practitioner should be particularly directed. Many, in other respects tolerably good operators, are most likely to fail in not introducing a sufficient quantity of gold in the upper palatine portion of the cavity. The author frequently meets with cases in which the Avails of the cavity are perfectly sound, and every other part of the filling well consolidated ; but here, upon the application of a wedge-pointed instrument, the gold is easily perfo- rated. He Avould, therefore, advise the inexperienced operator to test this by severe pressure Avith a sharp wedge-pointed instrument, as well, indeed, as every part of the filling, before leaving the operation. There is also one other precaution applicable to fillings in the approx- imal surfaces of the incisors and cuspids, as Avell as of the molars and bicuspids; it relates to overlapping portions of gold under the free edge of the guin, which must be carefully and completely removed before the operation can be regarded as complete. In filling a cavity in the buccal surface of an upper bicuspid or molar, on cither side of the mouth, the gold may be introduced with the instruments represented in Figs. 104, 114. The latter is better adapted for the left side, but may also be used on the right. The straight Avedge-pointed instrument may also be advantageously em- ployed on this side. The first folds of gold should be placed against the posterior wall, proceeding from behind forward, and pressing the folds against each other as compactly as possible. When the cavity has a large orifice, and is rather shalloAV, or in other respects badly shaped for the retention of the gold, the operation is often tedious, dif- ficult, and perplexing. But under favorable circumstances a filling may be almost as readily introduced here as in any other part. The palatine surface of a bicuspid or of a molar is rarely attacked by caries ; on the latter, it is usually seated in a depression at the termi- nation of a fissure leading from the posterior depression in the grinding surface. It is usually situated near the posterior palato-approximal angle of the crown, about half-way between the gum and the coronal extremity of the tooth. It sometimes happens that the walls of these fissures are affected Avith caries throughout their Avhole extent, requiring to be filled from the depression in the grinding to its termination on FILLING TEETH. 317 the palatine surface. In this case, the portion of the cavity on the grinding surface may be first filled; then the operator may proceed to fill the palatine portion in the same manner as if it were a simplecavity, placing the first folds of foil, in the case of a right molar, against the upper and posterior side of the opening, with an instrument like the one represented in Fig. 114. Great care is necessarv to prevent the instrument from slipping. It often happens, too, that the orifice becomes choked with foil before the cavity is half filled. This, indeed, is liable to occur in filling any cavity in any tooth; and when it does happen, unless a sufficient amount of pressure is applied to make a free opening into it, the filling will be imperfect, and the object of the opera- tion wholly defeated. When the cavity is situated in a left molar, the gold may be introduced with the instruments represented in Figs. 104, 117, placing the first folds against the upper wall of the cavity, and proceeding downward. The curvatures of the points of condensing instruments may be simi- lar to those employed for the introduction of the gold. The process of condensing the extruding portion of a filling in the buccal or pala- tine surface of a molar, as well as in the approximal surface of almost any isolated tooth, may be greatly aided by properly constructed for- ceps. The following cuts of Prof. Flagg's patterns will convey a more correct idea of their construction than any description that can be given. They are provided with both straight and curved points. Fig. 123. Fig. 123 is astraight forcepsused forcondensing plugs betAveen teeth, upon the mesial or lateral faces above or below, the plugs being located near the cutting edges of the incisors, the cusp; of the cuspids or bi- cuspids, and the buccal edges of the approximating faces of the molars. Fig. 121. Fig. 124 is used for condensing such plugs or parts of plugs as are located bctAvten incisors, cuspids, and bicuspids of the upper jaw near 348 FILLING TEETH. their necks, and the lingual or palatine edges of the approximal plugs as they may pertain to superior or inferior teeth. Fig. 125. Fig. 125 is intended for condensing plugs upon the labial, palatine, and lingual faces of incisors and cuspids above and below, also upon the buccal, palatine, and lingual faces of bicuspids and molars above and below, right and left sides. It is only, however, in a small number of cases that these instiu- ments can be advantageously employed. The credit of the invention of plugging forceps belongs, Ave believe, to the late Dr. H. H. Hayden. A tubercle, of greater or less size, is sometimes found on the anterior palatine surface of a molar, near the crown. Between this and the body of the crown, a deep depression is often seen, which becomes the seat of caries; but the removal of the diseased part, and the introduc- tion of a filling is so simple, that a special description of the operation is not deemed necessary. II. With Adhesive Gold Foil. — In forming cavities in the approxi- mal surfaces of bicuspids and molars, it is essential, in the majority of cases, to separate the teeth either by means of pressure or by cutting away a portion of the croAvns. When they are very close together, it is often impossible to gain suffi- cient space by pressure, and it then becomes necessary to resort to the enamel chisel and file, cutting aAvay a portion from each tooth, when both are decayed, and from one only, if the other is in a sound condi- tion. The former practice in separating these teeth Avas to cut away so much of the entire approximal surface as to form a V-shaped space of sufficient extent to enable the operator to reach the cavity easily. But by this method the croAvn of the tooth Avas disfigured, and a space formed in which food readily collected, and became a source of con- siderable annoyance. To avoid this, the practice iioav is to cut through the grinding surface to the approximal cavity, mortising this opening, and thus preserve the palato- and bucco approximal angles, while at the same time the shape of the opening through the grinding surface ma- terially assists in the retention of the filling. In preparing these cavi- ties for adhesive gold foil,'at least two good retaining points should be made at the cervical wall and tAvo under-cuttings at the cusps, which have been preserved by the method of gaining space just described. FILLING TEETH. 349 But one of these retaining points, in connection with the two under- cuttings at the cusps, will often secure the filling, when the nature of the case will not allow of more being made. In preparing a cavity on the posterior approximal surface of a molar tooth, access is obtained by cutting through the grinding sur- face in the manner before referred to; then, by means of instruments more or less curved, the buccal and palatine Avails are made parallel with each other, under-cuttings formed at the cusps, and retaining points drilled in the cervical Avail at different angles. Advantage is also gained from having the cervical Avail slightly undercut. In introduc- ing the gold into a cavity of this nature, many prefer placing a pol- ished plate of metal back of the cavity in the space between the teeth, and condensing the gold firmly against it in building up this portion of the crown. By this method a good support is obtained, and, after all the gold necessary is introduced and consolidated, the metal plate is removed. In filling grinding surface cavities in the molar teeth, where the decay has extended along one or more of the crown fissures, Avith adhesive gold foil or crystal gold, the gold is first introduced into the bottoms of the crown fissures, and built up to their orifices, thus completing the filling of these fissures before the central cavity is filled. In preparing cavities extending in the form of grooves over the buccal and palatine surfaces of the bicuspids and molars, all projecting por- tions of enamel should be cut aAvay, so as to ;i11oav these cavities to be but little larger within than at their orifices; and the ends of the groove, which are usually shallow, should be made as deep as the cen- tre. One retaining point may then be made in each of the two walls forming the ends of the groove-like cavity, or one retaining point in the posterior Avail, in connection with an under-cutting in the anterior one, Avill answer for the retention of the filling. In introducing the gold into a cavity of this form, the retaining points are first filled and the gold built across the floor of the cavity from one to the other, and from the base thus formed to the orifice. When a cavity upon the buccal or palatine surface extends under the free margin of the gum, it is necessary to either force the gum away by pressure with pledgets of cotton, or to remove the portion overlapping the cavity. The hem- orrhage which folloAVS this latter method may be checked by any of the haemostatic agents in use, such as tannin, phenol sodique, creosote, ptwdered subsulphate of iron, etc., and a few layers of bibulous paper applied to the gum during the operation of filling the cavity. FILLING THE INFERIOR INCISORS AND CUSPIDS. The operation of filling a lower incisor or cuspid is far more difficult than filling an upper. It is fortunate, therefore, both for the dentist 350 FILLING TEETH. and the patient, that the lower incisors an.1 cuspids are less liable to caries than the upper. The constant tendency of the lower jaw to change its position is em- barrassing to the dentist in operating on any of the ts.:t'.i in it, and in case of the incisors and cuspids it is sometimes peculiarly perplexing. To prevent this, all the effort the operator can make with his left hand is frequently required. From the backward inclination, too, of these teeth, it rarely happens that the gold can be introduced from the lingual side of the arch ; consequently, it is necessary to make the spues as wide anteriorly as posteriorly. But as the teeth are comparatively small, the separation, when made with a file, should be no wider than is absolutely necessary for the removal of the diseased part and the introduction of the gold. When, however, it can be done with safety, the separation should be made with a piece of rubber or other sub- stance between the teeth, in the manner before described. While operating on the lower teeth, the head of the patient should occupy a more perpendicular position than while operating on the upper; this may be done either by lowering the seat or raising the head-piece of the chair. When by the latter, it will be occasionally necessary for the operator to stand upon a stool five or six inches in height. In filling a cavity in the right approximal surface of a lower incisor or cuspid with non-adhesive gold, foil, the following method is recom- mended. The cavity being prepared, and a sufficient quantity of gold foil made into a small roll, or folded lengthwise, as the operator may prefer, with the left arm over the patient's head, the chin is gently grasped with the left hand, Avhile the thumb is placed against the lingual surface of the tooth, the forefinger serving to direct the gold and point of the instrument, and also to depress the lower lip. The folds of gold in their introduction are pressed firmly against the lower wall of the cavity. The instrument employed for this purpose may be shaped like the one represented in Fig. 126, with a very small Fig. 127. fr—^m—-—-_^g wedge-shaped point, and held ns in Fig. 1*1. The consolidation of the gold may be effected partly with the same instrument, partly with a round-pointed one, shaped as shoAvn in Fig. 127, and partly with an instrument shaped as in Fig. 113. The tooth should be firmly held between the thumb and forefinger of the left hand to prevent it from being moved in its socket by the pressure of the instrument. When the incisors are very small, and the caric3 has spread over a Tig. 12G. FILLING TEETH. 351 large portion of the side of the tooth, it is often difficult to form a suitable cavity for the retention of a filling without penetrating to the pulp-cavity. In such cases, the patience and skill of the operator are frequently taxed severely in obtaining a sufficiently secure support for the gold. But this he can usually do, if he can make the bottom of the cavity as large as the orifice, even though it have but little depth. The manner of introducing a filling in the left approximal surface is very similar. The left arm and hand, as Avell as the thumb and forefinger, are all disposed of in the manner just described. The same instruments, too, may be employed for introducing and consolidating the gold, though in the first part of the operation the instrument (Fig. 109) may often be advantageously substituted for the one in Fig. 125. Nothing has been said with regard to fillings in the labial or lingual surface of loAver incisors and cuspids. Although caries rarely attacks either of these surfaces of a lower incisor, it does sometimes develop itself in the labial surface of a cuspid; but the operation of intro- ducing a filling here is so simple, that a separate description of the .manner of it is not deemed necessary. The operation of forming cavities in the inferior teeth and intro- ducing adhesive gold foil and crystal gold is the same as that de- scribed for the superior teeth, and a second description is therefore not considered necessary. As absolute dryness is essential in manipu- lating with the adhesive forms of gold, the reader is referred to the various methods and appliances before described for drying cavities, and protecting them from moisture. In filling the inferior teeth, the rubber coffer-dam Avill be found to be a valuable appliance for ex- cluding all moisture from both the gold and cavity, and the saliva- pump an efficient adjunct to this dam for relieving the mouth of the saliva as it accumulates in prolonged operations. For controlling the movements of the tongue, the tongue and duct compressor can be used in connection with pads of bibulous paper placed upon the mouths of the duets beneath the tongue. Prepared spunk is also used success- fully on the mouths of the sublingual and submaxillary ducts, for con- trolling the flow of saliva. FILLING THE INFERIOR MOLARS AND BICUSPIDS. In filling a cavity in the grinding surface of a right lower molar or bicuspid, the operator may stand on the same side of his patient, and a f'e.AV inches higher than Avhile operating on an incisor or cuspid. With his left arm placed over his patient's head, the tooth may be grasped with the thumb and forefinger of the left hand, while the middle finger is placed by the side of the chin; the other two should 352 FILLING TEETH. be placed beneath it. After preparing the cavity, non-adhesive gold foil may be introduced with an instrument like the one represented in Fig. 117, and held as shoAvn in Fig. Ill, pressing the folds against the posterior wall of the cavity. In condensing the gold after the cavity is filled, use the instrument represented in Fig. 118. Sometimes, however, the one shown in Fig. 120, which may be held as seen in Fig. 105, answers a better purpose; but a greater amount of force can be exerted Avhen held in the man- ner shown in Fig. 121, previously wrapping it with the corner of a napkin, to prevent the small part of the instrument from hurting the little finger. The kind of instrument, and the manner of holding it, will, after all, have to be determined by the operator. During the introduction and consolidation of the gold, the lower jaw should be firmly held Avith the left hand, to prevent it from moving, and from being too much depressed. This precaution is the more necessary, as the muscles of the lower jaw and the articular ligaments are seldom strong enough to resist the amount of force required in the operation. In filling a cavity in the grinding surface of a tooth on the left side, the dentist may sometimes operate to greater advantage by standing on the same side. In this case, the commissure of the lips should be pressed back with the thumb of the left hand, placing it on or against the tooth to be filled, Avhile the forefinger passes in front of •the chin, and the other three beneath it. As a general rule, hoAvever, he Avill be able to operate more conveniently by standing on the right side of his patient, and hold the tooth and the chin in the manner be- fore directed. In either case, the gold, in its introduction, should be pressed against the posterior Avail of the cavity. The foregoing general directions will be found, for the most part, applicable to the introduction of a filling in the approximal surfaces. When the croAvns of the teeth are long, and the cavity situated near the gum, the operation is sometimes very difficult and tedious, requir- ing all the patience and skill the dentist can exercise to accomplish it securely. This difficulty is increased when the shape of the cavity is unfavorable for the retention of the gold; or, in other Avords, when the cavity is shalloAV, and has a large orifice. There is also another very serious difficulty Avhich the operator encounters in the introduc- tion of a filling in the approximal, and also in the buccal, surface of a lower molar or bicuspid. The flow of salh'a is often so profuse that the Avhole of the loAver part of the mouth is completely filled, and the tooth inundated before it is possible to introduce a sufficient quantity of gold to fill the cavity. This not only retards the operation, but it also renders it more difficult and perplexing; for it is necessary to force out every particle of moisture from the cavity and from between FILLING TEETH. 353 the different layers of gold, before the necessary cohesive attraction between them can be secured. If this is not done, or, at any rate, if all the moisture is not forced from the cavity, and the gold sufficiently consolidated to render it impermeable to the fluids of the mouth, the operation will be unsuccessful. Ordinary foil, sometimes called non-adhesive, when introduced in folds lying parallel with the sides of the cavity, keeps its place by the close lateral contact of the folds against each other and the walls of the cavity. Hence such fillings may prove successful, although done " under water," provided the lateral pressure is sufficient to force out the saliva from between the layers of foil. But if the folds are laid in parallel with the bottom of the cavity, the operation will fail, in consequence of the scaling off of the successive layers Avhich have no adhesion. Crystal gold and adhesive foil fillings depend for their success upon the perfect adhesion of their component pieces; there- fore, the slightest moisture, or even dampness, while being introduced, is fatal to their durability. For the purpose of obviating this difficulty, a variety of means have been proposed, the most important of which have already been de- scribed, and need not be again referred to. In the introduction of non-adhesive gold on the right side, it may be pressed against the "buccal Avail of the cavity on the left side, or against the lingual wall. Either «f the instruments represented in Figs. 103- and 114 may be employed for the introduction of the gold, whether the cavity be situated in the anterior or posterior approximal surface of the tooth, and may be held in the hand in the manner shown in Fig. 111. In filling a cavity in the lingual and posterior approximal angle of a first or second bicuspid, and especially from the loss of the tooth behind it, when there is a backAvard inclination of the organ, great care is necessary to prevent the instrument from slipping and wound- ing the lower lip. The most convenient position for the operator in this case is on the left side, and partly in front of the patient. The tooth may then be firmly grasped between the thumb and forefinger of the left hand, or the thumb alone pressed against the outside of the tooth ; in either case it is to be used as a rest for the ring-finger of the right hand, during the introduction and consolidation of the gold. But the locality of the cavity is such, especially when the mouth of the patient is small, that it can only be seen with great difficulty. Hence the operator is constantly liable to place the point of the in- strument on one side of the orifice against an overlapping portion of given. The injection of the tooth from the vessels of the lining mem- brane and pulp is of frequent occurrence in teeth to Avhich arsenic is applied for the purpose of merely destroying the sensibility of the den- tine. At the first meeting of the American Society of Dental Surgeons, Dr. Hayden mentioned a case that had a short time before fallen under his observation, and several others were cited by the author at the same time. Since then he has met with numerous cases in which this had occurred. It is doubtless the result of increased vascular action, excited in the lining membrane and pulp by the action of the arsenic, and it proves that the vessels of teeth, under certain circumstances, are capable of conveying red blood. It occurs, however, much more frequently in the teeth of young than in those of old persons. Destruction of the Pulp. — With regard to the best means of destroy- ing the nerve, or rather the pulp of the tooth, there exists much diversity of opinion. There are two methods by which this may be accomplished—one by immediate extirpation Avith an instrument, and by actual cautery; the other by the application of some devitalizing agent, as arsenic. Each method has its advocates. For the removal of the pulp by extirpation, there are different forms of instruments employed, such as a three- or four-sided broach, barbed for some distance from the point, which is thrust as far up the pulp canal as is possible, then rotated and Avithdrawn, bringing the pulp Avith it. Fig. 131 represents a broach of this kind, Avhich may be used with or Avithout a holder. Another form of broach is used for this operation Avhich is not barbed, but thrust into the pulp for the purpose of so lacerating it that it may afterward be removed with nerve instruments Avithout much pain. A fine round steel wire, from which the temper has been drawn, and having a flat point bent on an angle of about forty degrees, is also used for extirpating the pulp. The edge of the point, in introducing this instrument, is pressed against one Avail of the canal and gradually forced up as far as it will enter, when it is suddenly turned so as to excise the pulp, and on with- drawing the instrument bring the severed organ with it. For extirpating the pulps of the molar teeth, a larger instrument is re- quired, Avhich is thrust into the pulp chamber and rotated so as to sever the body of the pulp from the branches filling the root canals. The small nerve instruments are then employed for removing these branches. The actual cautery consists in thrusting a Avire, heated to a Avhite heat, up the canal; but as this is considered a barbarous method, FILLING PULP-CAVITIES AND ROOTS OF TEETH. 371 it is not resorted to by practitioners in this country. Besides, periosteal inflammation is often a result of its use, and the pain following its application is sometimes very severe. Arsenious acid has long been used, in connection Avith FlG- 131- sulphate of morphia and creosote, to devitalize the pulp; ; the arsenic and morphia being mixed in equal parts, and \ taken up on a small pellet of cotton saturated with creosote, : which is introduced directly upon the exposed portion of the pulp, and the cavity filled Avith wax or cotton saturated with a solution of gum sandarach and alcohol. The morphia was formerly supposed to modify the irritating action of the arsenious acid ; but since this has been discovered not to be the case, its use has been dispensed with by many. Water, alcohol, and ether are employed as substitutes for the creo- sote, and in some cases are preferable. The arsenious acid is at times combined with an equal part by Aveight of pul- verized charcoal, on account of the antiseptic properties of this latter agent, and also on account of its mechanical action in preventing the dentine from absorbing what is intended for the pulp alone. A favorite mixture is knoAvn as 'nerve paste;" but when a definite quantity of the arse- nious acid is desired for application to a pulp, it is better to employ the dry form. Various formulas are in use for the preparation of devitalizing mixtures, such as equal parts by Aveight of arsenious acid, and either the sulphate or acetate of morphia; three parts by Aveight of arsenious acid to two parts of morphia; two parts of arsenious acid and one part of morphia. Creosote is generally employed to combine the ingredients, and by some is regarded as a solvent of the arsenic. The thirtieth part of a grain of arsenious acid is the average quantity employed to devitalize the pulp. The length of time the preparation should be allowed to remain \raries from six to twenty-four hours. Not unfrequently cases are met Avith Avhere repeated applications of the prepa- ration fail to destroy the vitality of the pulp, which is doubt- less owing, in cases where the organ is fairly exposed, to a peculiar condition at the time the application is made, which enables it to resist the absorbent action of the arsenic. In such cases a preparation composed of tannin and creosote lias proved serviceable. To the use of arsenic and all similar agents, Dr. Harwood, of Boston, is strongly opposed. He states in a letter to the author, written in 1850, that "they cause death and slough- r372 FILLING PULP-CAVITIES AND ROOTS OF TEETH. ing in the parts to which they are more immediately applied, and irri- tation and unmanageable trouble in the parts next beyond those they absolutely kill. In other words, they irritate the parts beyond the dental cavity, and from this cause (and perhaps from chemical injury to the teeth itself) the periosteum of the root and socket becomes the seat of great and frequently of uncontrollable difficulty." Entertain- ing these views, he regards the use of such means as opposed both to experience and sound philosophy, and adopts, without knowing that the same thing had been done by others, what he believes to be a more correct practice — immediate extirpation. He thus describes his method of accomplishing this object: "I first effect such an opening as will enable me to approach the exposed pulp in the line of its axis, or as nearly so as circumstances will permit. Then, having carefully but sufficiently exposed the sur- face of the pulp, I pass down to the apex of the root, through the pulp, a small untempered steel instrument, with a trocar-shaped point, and revolving it once or twice sever the vessels and nerve. This, as any one knoAvs, who is accustomed to inserting artificial teeth, produces but a slight and momentary pain. I then, by means of minute instruments, adapted to the purpose, endeavor to remove every portion of the severed pulp and lining membrane, and, as soon as the hemorrhage ceases, dry and fill the cavity. "I have sometimes only filled the canal at the first sitting—leaving the body of the tooth to be treated after a few days. This course has been adopted from a fear that the pressure necessary to complete the Avhole operation might enhance the danger of inflammation and suppuration." This is prudent, but experience does not convince me that it is necessary. " It should be borne in mind, that at the point Avhere the vessels and nerve in question enter the root, the passage is much smaller than it is immediately within. This strait will be easily recognized when reached, by the touch, the instrument appearing to be arrested by an obstacle, and not by being Avedged in a narrow passage. Care should be taken, I think, that the instrument is not allowed to pass through the strait, either by being too small, or by being revolved there till it cuts its way through. For, by Avounding the parts without the tooth, and forcing particles of bone out upon the parts external to the root, the danger of an unfavorable result would be greatly increased." Dr. Harwood adds, in conclusion, that he believes it is better to make the division of the parts a little within the strait, though he does not regard the matter as being yet fully settled by observation and experience. As to the success of the practice, he speaks very confi- dently ; not having had a case treated in this manner where the patient FILLING PULP-CAVITIES AND ROOTS OF TEETH. 373 and pulp Avere healthy, in which there has been a single symptom of alveolar abscess. In a paper read before the American Society of Dental Surgeons, at the meeting held in the city of New York, August, 1845, and published in the sixth volume of the American Journal of Dental Science, p. 15, Dr. E. J. Dunning maintains very similar views with regard to the means most proper to be employed for the destruction of the pulp of a tooth. He says: " The destruction of the nerve by mechanical means has been prac- tised to a small extent by dental surgeons for many years: but on account of the severe pain which in many cases attends it, as well as from the fact that, in the manner in Avhich it has generally been prac- tised, it has proved no more successful than other and less severe methods, it has been considered rather in the light of a dernier res- sort." This he believes to be owing to the fact that the nerve is often only punctured and lacerated, and afterward shut up in the tooth and left to decompose. To prevent Avhich, he says, the Avhole nerve should be removed, and its place filled with gold. Again, Dr. Dunning remarks: "The instrument which I have used to excavate the roots is a delicate probe of steel, perfectly annealed. The point should be converted into a very slight hook, and made sharp, so as to bring away the nerve or other matter with Avhich the cavity may be filled. For the removal of the nerve in the chamber of the cnnvn, in molar teeth, as Avell as for enlarging the cavity, so as to give free access to each of the roots, a burr-drill is very useful. As these teeth are generally very much decayed, it Avill be found ad- visable, when the cavity is on the side of the crown, to remove its' edges in such a manner as to admit the light directly upon the open- ings of the roots. This will facilitate the operation very much, and at the same time give strength to the Avails that are to contain the stopping." When the nerve has been destroyed in the manner above described, Dr. Dunning says that the operation, so far as he has been able to observe, has been successful in every case. On the different methods of destroying the nerve, Dr. J. H. Foster says: " It is a difficult matter, and I have generally found it utterly futile, to attempt to induce patients to submit to the removal of the pulp by extraction or excision Avith instruments, in those cases in Avhich it becomes necessary to destroy vitality before the teeth can be filled. To obtain the consent of the patient by a representation of the advan- tages, in its immediate effects, of this mode of treatment by extirpation as contrasted with the more slow and uncertain practice, by the aid of chemical agents, has been my earnest endeavor. I do not remember a single case of the removal of the dental pulp by an instrument — 374 FILLING PULP-CAVITIES AND ROOTS OF TEETH. the gold being inserted into the dental cavity immediately after the hemorrhage has been checked — which has resulted in alveolar abscess." Dr. Foster, hoAvever, generally employs arsenious acid, with sul- phate of morphia, one part of the former to four of the latter, applied on a small pellet moistened with creosote. After applying this di- rectly over the nerve, he covers it with a cap, to avoid pressure; then fills the external cavity with some soft material Avhich will exclude moisture. At the end of forty-eight hours he enlarges the dental cav- ity, removing its contents to the apex of the root: then, after Avaiting another forty-eight hours, he proceeds to fill the canal, leaving the cavity in the crown to be filled at a subsequent sitting. In performing this operation on molar teeth, Avhere there is a proba- ble chance of a favorable issue, and the preservation of these teeth is particularly called for, he thinks it important that the excavation should be done at intervals, so as to cause as little irritation at each sitting as possible, and that the filling of the different cavities in the tooth be also proceeded Avith in like manner. Dr. Maynard — Avho has been as successful in filling the pulp-cavity and roots of teeth as any other practitioner, and has probably had more experience, having been in the habit of performing the operation since 1838 — having thoroughly tested the method of destroying the nerve by immediate extirpation with an instrument, as Avell as that by the application of arsenious acid, gives the preference to the latter. His method, as described by Dr. Westcott, in vol vii., p. 286; of the American Journal of Dental Science, is as folloAVS : He takes white Avax, and Avorks it into cotton or lint until it is tho- roughly mixed together. With this he fills the cavities in the tooth. But, before doing this, he exposes the nerve as much as possible, ap- plies the arsenic, and caps the orifice Avith a cup-shaped plate of lead, the convex side outward. While this is carefully kept in place, he fills the cavity with the cotton and Avax, very carefully and perfectly, in such a Avay as not to shut in and compress any air Avhich might press upon the nerve. This packing, as introduced by Dr. Maynard, will keep the "medicine," as he terms it, perfectly dry for twenty-four hours, or longer. After removing this packing and the preparation, he proceeds to remove the nerve. Instead of attempting to do this at once, he begins by cutting on every side of the orifice, so much enlarging it as to be enabled to remove the nerve without pressing the contents of the cavity upward. His probes are Objects of peculiar interest, especially those for extir- pating the nerve. Some of them are made from the main-spring of a watch, by filing or grinding them sufficiently narrow to enter the FILLING PULP-CAVITIES AND ROOTS OF TEETH. 375 smallest space Avhich he Avished to probe. In this Avay he secures the most perfect spring temper, a point not easily attained in so frail an instrument as a probe adapted to this purpose. These probes are bearded by cutting them with a sharp knife—the beard pointing back- Avard. With different sizes of these and other probes, and by enlarg- ing the cavity from time to time, he removes the nerve to the extremity of the root. Dr. Arthur, in a series of ably written articles, published in the American Journal of Dental Science, on the treatment of caries of the teeth, complicated with disorders of the pulp and peridental mem- brane, recommends the use of cobalt for destroying the nerve as pre- ferable to any other agent or means that have been employed for the purpose. But as arsenic is the active principle of cobalt, it is to this agent it owes its efficacy. It has not, however, been found to be as effective as the arsenious acid. In the destruction of the pulp of a tooth, the author (Prof. Harris) has employed both mechanical and chemical agents. He has been in the habit, for more than tvventy years, of occasionally extirpating the pulp to the extremity of the root by introducing a very small untem- pered instrument, with a spear-shaped point; though not at first with the vieAV of aftenvard filling the pulp-cavity. He has also used the actual cautery and arsenious acid. To the last-named agent, as used by most dentists for destroying the vitality of teeth, he Avas at one time strongly opposed, and still believes a vast amount of injury is produced by it; but Avith proper care and judicious after-treatment, it may be used with safety, and, in most cases, with advantage. He now employs it for destroying the vitality of the lining membrane and pulps of the molar and bicuspid teeth, and occasionally applies it to the incisors and cuspids. As a general rule, hoAvever, when he Avishes to destroy the nerve of one of the last-named teeth, he extirpates it by thrusting a small instrument up the pulp-cavity to the extremity of the root. When he uses arsenic, he applies about the thirtieth or fortieth part of a grain, with an equal quantity of sulphate of morphia; placing it on a small piece of raw cotton, moistened with creosote or spirits of camphor, and sealing up the cavity with Avhite or yellow wax. At the expiration of seven or eight hours, he removes the Avax and arsenic, and afterward the pulp of the tooth. If the portion in the root is still sensitive, he applies it a second time; but he seldom finds it necessary to do so. Treatment Preparatory to Filling the Roots of Teeth.— The folloAving is the method of treatment, preparatory to filling the root, pursued by Prof. Gorgas, of the Baltimore College: "I remove carefully all dis- organized pulp and decomposed dentine; also all discolored dentine, 376 FILLING PULP-CAVITIES AND ROOTS OF TEETH. provided it does not weaken the walls of the cavity. Then, syringing out all loose particles of the debris with tepid water, I dry the canal to the apex of the root with floss silk; being careful to leave an end projecting so as to permit its easy removal. Several such pieces being used, a shorter piece is then saturated Avith creosote and passed to the end of the canal, leaving a slight projecting piece in the pulp-cavity, so that it may be seized with pliers when it is to be removed. "I then introduce into the pulp-cavity a temporary filling of Hill's stoppi ng, gu tta - perch a, or cotton mixed with Avax, or saturated with sandarach or shell-lac varnish. In tAventy-four hours the canal is ex- amined, and the creo- sote reneAved if neces- sary. When not the slightest odor of puru- lent secretion is percep- tible, I then apply on the floss silk chloroform mixed with white of egg, replace the filling, and Avait for several days. " If at the end of this time there is no trace of diseased action, I fill the canal with gold ; then wait a few days until all chance of irri- tation from the pressure used in the operation has passed away, and then complete the filling. But not unfrequently it is necessary to re- peat this course of treatment several times. In one case, tAvo months were required before the tooth was in a condition to warrant me in filling it. "In some cases I deem it prudent to insert a filling of 'Hill's stop- ping' for several months, especially when there is the slightest doubt of the arrest of the disease; for the gold once introduced into the canal, it is exceedingly tedious and difficult to remove it. Disease on the outside of the extremity of the root may be controlled by creosote and nitrate of silver, applied through the fistulous or an artificial opening in the alveolus. " Chloride of zinc may be used instead of creosote when the smell of the latter is particularly repulsive to the patient; and chlorinated lime or soda are excellent antiseptics. Any trace of the living nerve should be treated with arsenic, a minute portion of which may be in- troduced upon floss silk before commencing the creosote treatment." Fig. 132 represents a set of Dr. B. F. Arrington's nerve extractors, of drawn and spring temper. \ FILLING PULP-CAVITIES AND ROOTS OF TEETH. 377 Filling Pulp-Cavities and Roots of Teeth. — The method pursued by the author in filling the pulp cavities and canals is the same as that of Dr. Maynard, which is characterized by great neatness and dexterity. His instruments are of the most delicate kind, and are adapted to reach to the end of the canal, although it may not be entirely straight. In filling these roots, he uses very heavy gold, from No. 12 to 30. This is cut into strips corresponding to the diameter of the cavity, and is not doubled. The end of one of the strips is laid upon the end of one of his delicate pluggers, and carefully carried to the upper extremity of the root. This being effected, the instrument is withdrawn a distance, then returned, carrying with it another portion, till th is exhausted. In this Avay the Avhole root is filled; the cavity in the crown is then filled in the usual manner. Fig. 133 represents a set of instruments contrived by Dr. Palm- er, forming the ca- nals in the roots of the teeth. Fig. 134 represents Dr. Hunter's set of pulp canal pluggers, some of which are of drawn and others of temper. slight e strip spring 378 FILLING PULP-CAVITIES AND ROOTS OF TEETH. After the cavity of decay in the crown has been properly prepared, by means of the instruments represented in Fig. 133, the pulp chamber can be excavated and so shaped as to assist in the retention of the gold, as Avell as the canals leading from this chamber through the roots. Some operators drill out these canals, and thus give them the same diameter from their orifice at the pulp chamber to the apex of the root. Others are satisfied with cleansing them perfectly of all debris and decomposed dentine. Whichever method is pursued, care is necessary that the instrument is not passed beyond the foramen, which is more liable to occur in the case of young patients, Avhen the teeth are not fully developed, than afterward; for then there is generally such a decided contraction of the root canal near the apex as to arrest the progress of the instrument. When the cavity in the crown and the pulp chamber and canals are prepared, the gold is introduced by means of the instruments represented in Fig. 134. Besides the method of filling the roots, de- scribed as Dr. Maynard's, there are several others, one of which consists in rolling strips, or folds, of gold on a fine broach in such a manner as to form cone-shaped cylinders, somewhat longer than the canal is deep, of different sizes and density. The soft rolled are first introduced by means of the pliers, and carried up as near to the apex of the root as is safe, each one being condensed against the side of the canal. Suc- cessive cylinders are introduced in this manner and condensed until the canal is filled, the last ones which form the centre of the filling being dense. Pure gold Avire is sometimes employed for filling these canals, so shaped as to correspond in size and taper Avith the cavity. It sometimes happens that the canals in the buccal roots of the superior molars are so small as to preclude the introduction even of a small-sized bristle. In cases of this kind it is impossible to fill them, and fortunately, from their small size, they cannot serve as reservoirs for the accumulation of morbid matter. The canal in the palatine root is always much larger than in either of the buccal roots, and in a ma- jority of the cases is filled Avith comparative ease. After the canals are filled, some days should elapse before the operation of filling the croAvn cavity is performed. Although gold is the only metal suitable for filling root canals, yet some non-metallic substances have answered well Avhen employed for this purpose, principally on account of their non-conducting property, such as Hill's stopping and os-artificiel. For bleaching teeth which have become discolored from loss of vitality. the reader is referred to the chapter on " Necrosis." TOOTHACHE. 379 CHAPTER V. TOOTHACHE. PAIN in a tooth, toothache, or odontalgia, as it is technically termed, is a symptom of some functional or structural disturbance, either of the organ in which the pain is seated, or of some other part or parts of the body, but more frequently of the former than of the lat- ter. So variable is the character of the sensation, that any descrip- tion would fail to convey, to one A\ho has never experienced it, a cor- rect idea of its nature. The pain sometimes amounts only to slight uneasiness ; at other times the agony is almost insupportable. It may be dull, deep-seated, boring, throbbing, or lancinating. It may be slight at first, gradually increasing in severity until it amounts to the most excruciating torture, or it may come on Avithout any premonition Avhatever. It may be confined to a single tooth, or it may affect sev- eral at the same time. It may commence in one tooth, and pass from thence to another, and continue until every one in turn has been at- tacked. It may continue for hours and days with scarcely any cessa- tion ; or it may be intermittent, the paroxysms recurring at stated or irregular intervals, and each lasting from thirty minutes to one, tAvo, or more hours. CAUSES. The causes of toothache are almost as numerous as are the varieties of character which it exhibits. Irritation and inflammation of the pulp, and inflammation of the investing membrane,are among the most frequent; but it is sometimes referable to a morbid condition of the nerve or nerves going to a single tooth, or of the trunk from which several teeth are supplied ; also to derangement of the digestive organs, to increased nervous susceptibility of the uterus resulting from preg- nancy, amenorrhcea, etc., and to certain diatheses of the general system. Dr. Hullihen enumerates the folloAving as the causes of toothache: 1, exposure of the nerve; 2, fungus of the nen^e; 3, confinement of pus in the internal cavity; 4, a diseased state of the periosteum cov- ering the root; and, 5, sympathy. Dr. Heilden attributes it to conges- tion or inflammation, or to a lesion of the nerves of the lining mem- brane and pulp, or of the peridental membrane. Inflammation of the lining membrane and pulp may be produced by a blow upon a tooth, or by powerful impressions of heat and cold 380 TOOTHACHE. communicated through the enamel and dentine, or through a metallic filling; but it is more frequently occasioned by pressure, or by the direct contact of irritating agents, such as carious portion of the tooth, particles of food, acrid humors, and other irritating external substances. But inflammation is not always a necessary consequence of such im- pressions. Pain may be produced by them Avhen inflammation does not exist; in this case it usually subsides soon after the removal of the irritant. Indeed, the pulp of a tooth may be exposed for months, and subjected several times every day to the contact of foreign substances, without becoming the seat of inflammatory action ; and in the absence of this, the pain, though coming on with the suddenness of an electric flash, and often of the most excruciating kind, is seldom of long du- ration. But when inflammation exists, the pain, A\diich at first amounts only to a slight gnawing sensation, is more constant; after a while, it as- sumes a throbbing character, and if not promptly arrested, it increases in severity, and continues until suppuration of the lining membrane and pulp takes place. So long as it is confined to the parts within the pulp-cavity, the pain is not increased by pressure on the tooth, nor is the tooth started from the socket, as in periodontitis. The locality of the inflammation may also be distinguished by the fact that cold Avater or ice applied to the tooth generally gives relief. But the inflamma- tion rarely confines itself long to the interior of the tooth ; it usually soon extends to the periosteum of the root and its socket, when a somewhat different train of phenomena are developed. Suppuration, however, having taken place, an abscess soon forms at the extremity of the root. The severity of the pain attending odontitis (as inflammation of the pulp is technically termed, from the supposition that every part of the organ is involved in the diseased action), is, doubtless, owing to the fact that this exceedingly sensitive structure, as its vessels become injected, is prevented from expanding by the unyielding nature of the Avails of the cavity in Avhich it is situated. Its capillaries being thus dis- tended, must, as a necessary consequence, press upon the nerves Avhich are everywhere distributed through it, and the excruciatingly painful throbbing sensation, by which this variety of toothache is characterized, is produced by the pulsation of these vessels. Hence, increased action of the heart and arterjes, from whatever cause produced, augments the pain; it is also more severe at night, Avhile the body is in a recumbent posture, than during the day, because this position gives an increased fulness to the arteries of the head. The phenomena attending the inflammation, however, are influenced very much by the condition of the tooth and the habit of body of the patient. TOOTHACHE. 381 When the inflammation is acute, it extends to every part of the pulp and lining membrane. It also occurs more frequently before than after these tissues have become exposed, and generally terminates in suppu- ration. Chronic inflammation usually arises from partial exposure of the pulp, and may exist for months Avithout being attended with pain ; but the pulp, when thus affected, is more susceptible of injury by heat or cold, and by irritating substances; and the liability of the tooth to ache, especially at night, is greatly increased. Toothache caused by acute inflammation of the investing membrane is characterized by pain, at first dull, aftenvard acute and throbbing, soreness and elongation of the tooth, redness and tumefaction of the gums, and sometimes by swelling of the cheek; indicating the forma- tion of alveolar abscess. In this variety of odontalgia, the tooth is often so much raised in its socket as to interfere more or less with mas- tication. The pain attending the foregoing pathological conditions, when severe and protracted, is often accompanied by constipation, headache, dryness of the skin, flushed cheeks, fulness and increased rapidity of pulse, and other constitutional symptoms. The nervous susceptibility of the teeth is sometimes so much increased by organic and even functional disturbances of other and often remote parts, that the mere contact of the minute nerves of the pulp and the lining membrane against the Avail of dentine Avhich encases them, is attended with severe pain. This variety of odontalgia is termed sym- pathetic, and is supposed to be the result of the transfer of nervous irritation, or, more properly, of exalted sensibility of the dental nerves, arising from a morbid condition or functional disturbance of some other part. If this hypothesis be true, it is probable that with this height- ened nervous excitability there is a slight increase of vascular action in the pulp, with a corresponding increase of size in its capillaries; in consequence of which, it is fair to presume, the nervous filaments sup- plying these tissues Avould be apt to respond painfully to the undue pressure. Though pain, arising from this cause, may have its seat in sound as well as in decayed teeth, it occurs more frequently in the lat- ter than the former, owing to the fact that any structural alteration in the dentine adds to their already increased nervous excitability. Persons of highly excitable nervous temperaments, pregnant females, and individuals laboring under derangement of the digestive organs, are particularly subject to this variety of toothache. Odontalgia, arising from pathological conditions or functional disturbances of other parts, assumes a great variety of forms. The pain may be continued, but more frequently it is periodical; it may be confined to a single tooth, or it may attack half a dozen or more at the same time. It sometimes 382 TOOTHACHE. also alternates with the paroxysms of rheumatism or gout, the pain in such cases assuming the specific character of these diseases. Mr. W., aged forty, for fifteen years the victim of gout, came to me in 1830. The first right upper molar was carious, but the pulp not exposed. Ten or twelve days before each attack of gout, recurring every three or six months during the last five years, this tooth was the seat of a peculiar grinding, lancinating pain; becoming gradually more severe, but ceasing entirely as the gout symptoms came on; it returned as these subsided, and continued for two Aveeks. Filling the tooth gave temporary relief only, and it Avas found necessary to extract it. In what is termed neuralgic toothache, "the pain," says Dr. Wood, "is usually of the acute character ; sometimes mild in the beginning, gradually increasing in intensity, and as gradually declining, but usu- ally very irregular; at one time moderate, at another severe, and occa- sionally darting Avith excruciating violence through the dental arches. Not unfrequently it assumes a regular intermittent form. Instead of pain, strictly speaking, the sensation is sometimes of that kind Avhich is indicated Avhen Ave say that the teeth are on edge, and is apt to be excited by certain harsh sounds, such as that produced in the filing of a saw, or by mental inquietude, and by the contact of acids or other irritant substances. Neuralgic toothache sometimes persists, with intervals of exemption, for a great length of time. The diagnosis is occasionally difficult. When, hoAvever, it occurs in sound teeth, is par- oxysmal in its character, is attended with little or no swelling of the external parts, occupies a considerable portion of the jaAV, and especi- ally when it alternates or is associated Avith pain of the same character in other parts of the face, there can be little doubt as to its real nature." This variety of sympathetic toothache is perhaps induced by caries, or by the manner in which the teeth are arranged in the alveolar arch, or by some peculiar susceptibility of the parts; as is shown by the fact that the pain usually ceases on the removal of all such causes of irri- tation. But while, on the one hand, pain in the teeth may be caused by a morbid condition of other organs, these organs, on the other hand, frequently sympathize with the diseased condition of the teeth, and become, to quote the language of Mr. Bell, "the apparent'seat of pain. I have seen this occur not only in the face, over the scalp, in the ear, and underneath the lower jaAV, but down the neck, over the shoulder, and along the Avhole length of the arm." Cases of this sort are fre- quently met with. In treating of toothache, Dr. Good observes: "This is often an idio- pathic affection, dependent upon a peculiar irritability (from a cause we cannot easily trace) of the nerves subservient to the aching tooth, TOOTHACHE. 383 or of the tunics by which it is covered, or of the periosteum, or the fine membrane that lines the interior of the alveoli. But it is more frequently a disease of sympathy, produced by pregnancy, or chronic rheumatism, or acrimony in the stomach, in persons of an irritable habit. It is still less to be wondered at that the nerves of the teeth should often associate in the maddening pain of facial neuralgia, or tic douloureux, as the French writers sometimes term it; for here the connection is both direct and immediate. In consequence of this, the patient, in most instances, regards the teeth themselves as the salient points of pain (as they unquestionably may be in some cases), and rests his only hope of relief upon extraction; but Avhen he applies to the operator, he is at a loss to fix upon any particular tooth. Mr. Fox gives a striking example of this, in a person from whom he ex- tracted a tooth which afforded little or no relief; in consequence of which his patient applied to him only tAvo days aftenvard and requested the removal of several adjoining teeth, Avhich were perfectly sound. This he objected to, and suspecting the real nature of the disease, he immediately took him to Sir Astley Cooper, who, by dividing the affected nerve, produced a radical cure in a feAV days." The author is acquainted Avith a gentleman similarly affected. He has had all his teeth on the right side of both jaws extracted, Avithout obtaining any relief. There is still another cause of toothache, Avhich we should not omit to mention — exostosis; but from the obscurity of the diagnosis, the existence of the affection can seldom be determined Avith positive cer- tainty, except by the removal of the tooth. As we have already had occasion to treat of this disease, it is unnecessary in this place to dwell upon the subject. Finally, some teeth, from peculiar constitutional idiosyncrasy, are more liable to odontalgia than others. It sometimes happens that every tooth in the mouth is destroyed by caries Avithout being affected Avith pain, Avhile at other times teeth apparently sound become the seat of the most agonizing torture. TREATMENT. The first thing to be attended to in the treatment of toothache is the removal of the causes Avhich have given rise to it; this can only be done by carrying out the curative and remedial indications of the morbid conditions and functional disturbances with which it is con- nected. While these continue, it will be impossible to obtain perma- nent relief. The sensibility of the nerves supplying a tooth may often be obtunded, and the pain palliated by the application of stimulating and anodyne agents to the exposed pulp; but the relief thus procured 384 TOOTHACHE. is seldom of long duration. When their effects subside, the pain usu- ally returns with increased severity. When the pain arises from chronic inflammation and irritation, produced by external agents on an ex- posed portion of the lining membrane, such applications may often be employed with great advantage; and among those which have been used for this purpose are creosote, the oil of cloves, cinnamon, etc., laudanum, spirits of camphor, tannin, ether, and chloroform. But of all the remedies prescribed by the author, he has found none more use- ful in allaying the pain than the following: Sulphuric aether, • Si- Sulphuric aether, ■ Si- Powdered camphor, 3U- Creosote, gss. Powdered alum, • m- Ext. of nutgalls, . 3i. Sulphate of morphia, grs. ij Powdered cauiph., . ^ss. The alum should be very finely powdered, and all the ingredients well mixed before use. After removing all foreign matter and carefully drying the cavity of the tooth, a small bit of cotton or lint dipped in either of the above mixtures may be applied, and renewed several times a day, if necessary. The relief obtained is, in the majority of cases, almost instantaneous; but, as the effect is only temporary, the pain is apt to recur. The author has sometimes used a thick solution of gutta-percha in chloroform. The application of a drop or two of this to the ex- posed pulp is usually folloAved by the" immediate cessation of pain, and as the chloroform evaporates, a thin layer of gutta-percha re- mains, and serves for a time as a sort of protection to the pulp. But the only Avay in which permanent exemption from pain can be procured is by the extraction of the tooth or the destruction of the pulp; it often becomes necessary to have recourse to the latter, as there are many cases in which the patient cannot be prevailed upon to submit to the former, and as there are others in Avhich the retention of the organ is called for by some peculiar necessity. This may be effected either by immediate extirpation Avith a small, sharp-pointed elastic stilet or probe, by the actual cautery, arsenious acid,* cobalt, or chloride of zinc. Immediate extirpation, arsenic, or cobalt are the means usually employed for the purpose; but we have already de- scribed the manner in which the destruction of the pulp is effected by each of these. * The employment of arsenious acid for the destruction of an exposed dental piilp, and the relief of the pain arising therefrom, originated with the late Dr. Spooner, of Montreal; and in 1835 it was recommended to the profession by his brother, Dr. S. Spooner, of New York, in an excellent popular treatise upon the teeth. TOOTHACHE. 385 Pain in a tooth arising from acute inflammation of the pulp and lining membrane, can only be relieved by the extraction of the tooth, the destruction of the pulp, or by subduing the inflammatory action; the last can seldom be done except by the most energetic treatment in the very beginning in cases where the decay has not penetrated to the pulp-cavity. The propriety or impropriety of extraction will be de- termined by the amount of pain, the progress made by the inflamma- tion, the condition of the parts with which the tooth is immediately connected, the effect of the local disturbance upon the general system, the situation and importance of the tooth, and the extent of structural alteration which has taken place in the croAvn. If the retention of the tooth, on account of its location, or the loss of several other teeth, is of great importance to the patient, and the circumstances of the case justify a well-grounded belief that it can be preserved and ren- dered useful, without acting as a morbid irritant, the operation, if pos- sible, should be avoided. In this case, supposing the inflammation to have proceeded too far to be arrested, the pulp may be destroyed and the tooth treated in the manner described in another chapter. When the inflammation is produced by other causes than exposure of the pulp and the contact of external irritants, it may perhaps be successfully combated. The treatment is similar to that for local in- flammation in other parts of the body; the administration of saline cathartics, the application of leeches to the gum of the affected tooth, abstinence from animal food and from stimulating drinks. If the pulse is full and hard, blood may be taken from the arm with advan- tage. Should these means fail to arrest the inflammation, and suppu- ration take place, the formation of alveolar abscess may be prevented by promptly perforating the crown of the tooth for the escape of the matter; but such cases usually terminate in periodontitis, Avhich per- haps arises as frequently from this as from any other cause. As the treatment of periodontitis or inflammation of the investing membrane is described in another chapter, it is unnecessary to repeat it. But Avhen the formation of alveolar abscess is threatened, the removal of the tooth, in many cases, will be found necessary. If it be an incisor or cuspid, however, the operation should be performed as a last resort. Toothache assuming a rheumatic or gouty character calls for a some- what different plan of treatment. In addition to the local means already described, it may be necessary to adopt the constitutional treatment applicable to rheumatism and gout. When the pain arises from increased vascular action and nervous irritation of the pulp, oc- casioned by a disordered condition of the digestive organs, and assumes an intermittent form, an emetic or cathartic, folloAved by the use of 2o 386 EXTRACTION OF TEETH. quinine, will generally afford relief, provided caries has not penetrated to the pulp-cavity. If dependent on general nervous irritability of the system, tonics, exercise, change of air, or such other constitutional measures as the peculiarities of the case may indicate, should be re- commended. The extraction of the tooth is the only remedy that can be relied upon for relief of pain arising from exostosis of the root. Dr. Good, however, thinks it may be cured in the early stages by the use of leeches and mercurial ointment, and others recommend the internal use of iodide of potassium. CHAPTER VI. EXTRACTION OF TEETH. THERE are few operations in surgery that excite stronger feelings of dread, and to which most persons submit with more reluc- tance, than the extraction of a tooth. Many endure the tortures of toothache for weeks and even months rather than undergo the opera- tion ; and, indeed, when we take into consideration the frequent acci- dents occurring in its performance by awkward and unskilful individ- uals, it is not surprising that it should be approached Avith apprehen- sion. But when performed by a skilful hand and Avith a suitable instrument, the operation is always safe, and in a large majority of the cases may be effected with ease. Dr. Fitch relates a case which will serve to illustrate the above re- marks. The subject, a resident of Botetourt County, Va., in having the second right superior molar extracted by a blacksmith, had a large portion of the jaw and five other teeth removed at the same time. " The roots of his tooth," says Dr. Fitch, " were greatly bifurcated and dovetailed into the jaw, and would not pass perpendicularly out, though a slight lateral motion Avould have moved them instantly. The jaAV proved too weak to support the monstrous pull upon it, and gave way between the second and first molars, and Avith it came both the anterior and posterior plates of the antrum. The broken portion ex- tended to the spongy bones of the nose, and terminated at the lower edge of the socket of the left front incisor, containing six sound teeth, namely, the first molar, the bicuspids, cuspid, and incisors of the right side—six in all. The soft parts were cut away Avith a knife. A severe hemorrhage ensued, but the patient soon recovered, though with excess- ive deformity of his face and mouth." EXTRACTION OF TEETH. 387 Dr. Cross, of North Carolina, related to the author, in 1838, a case very similar to the one just quoted. The operator in this, as in the other instance, was a blacksmith ; in attempting to extract one of the superior molar teeth, he brought away a piece of the jaAV containing five other teeth, together with the floor of the antrum and its posterior and anterior walls. We have adverted to these cases to show the impropriety and dan- ger of intrusting the operation to individuals possessing neither knowl- edge of its principles nor skill in its performance. Injuries occasioned by the operations of such persons have frequently come under the immediate observation of the author, Avith Avhom it has always been a matter of surprise that an operation, to which such universal repug- nance is felt, should ever be confided to them. The removal of a wrong tooth, or of tAvo or three, instead of one, are such common occurrences, that it were well if the precautions given by the illustrious Ambrose Pare1 were more generally observed. So fearful was he of injuring the adjacent teeth, that he always isolated the tooth to be extracted Avith a file before he attempted its removal. He regarded it as of the greatest importance that a person who extracted teeth should be expert in the use of his " tooth mullets; for unless he knows readily and cunningly how to use them, he can scarcely so carry himself but that he will not force out three teeth at once." Although great improvements have been made since his time in the construction of extracting instruments, yet even now the accidents to which he alludes are of almost daily occurrence. It is surprising that an operation so frequently called for should receive so little attention from medical practitioners, by Avhom, though not strictly belonging to their province, it must frequently be per- formed. This neglect can only be accounted for by the too general prevalence of the idea that little or no surgical skill is necessary to its performance. But every physician residing in the country, or Avhere the services of a skilful dentist cannot ahvays be commanded, should provide himself with the proper instruments, and make himself acquainted with the manner of performing this operation. INDICATIONS FOR THE EXTRACTION OF TEETH. With regard to the indications that determine the propriety of ex- traction, the author does not deem it necessary to say much in this place, as they are fully pointed out in other parts of the work. It may be avcII, hoAvever, to briefly mention, in this connection, a few of the circumstances A\Thich call for the operation. Beginning Avith the teeth of first dentition, it will be sufficient to state, that when a tooth of replacement is about to emerge from the 388 EXTRACTION OF TEETH. gums, or has actually made its appearance, either before or behind the corresponding milk tooth, the latter should at once be removed; and when the aperture formed by the loss of this is so narrow as to pre- vent the former from acquiring its proper position, it may sometimes be necessary to extract an adjoining temporary tooth. For more ex- plicit directions upon this subject, the reader is referred to the chapter on the management of second dentition. Alveolar abscess, necrosis of the walls of the alveolus, and pain in a temporary tooth, which 'cannot be cured by any of the usual remedies, may be regarded as in- dications which call for the operation. The principal conditions which should determine the extraction of a permanent tooth may be enumerated in the following order: First, Avhen a molar, from the loss of its antagonizing tooth, or from other causes, has become partially displaced, or is a source of constant irri- tation to the surrounding parts. Second, a constant discharge of fetid matter from the nerve-cavity, through a carious opening in the crown. There may, hoAvever, be circumstances which Avould justify a practitioner in permitting or even advising the retention of such a tooth ; as, for example, when the discharge of fetid matter is not very considerable; also, where the tooth is situated in the anterior part of the mouth, and cannot be securely replaced with an artificial^substitute. The secretion of fetid matter may, in some cases, by judicious treatment be arrested, the tooth preserved for many years by plugging ; and so the morbid in- fluence it would otherwise exert upon the surrounding parts may be counteracted. A front tooth should not be sacrificed unless called for by some very urgent necessity ; neither should an upper incisor nor cuspid be permitted to remain in the mouth, if it exerts a manifestly morbid action upon the surrounding parts: for in this case the conse- quences resulting from its retention in the mouth may be worse than the loss of the tooth. Third, a tooth which is the cause of an incurable alveolar abscess, should not be permitted to remain; but if it be an incisor or cuspid, and the discharge of matter through the gum is small, occurring only at long intervals, and especially if the organ cannot be securely re- placed with an artificial substitute, it may be permitted to remain. An incurable abscess in the socket of a bicuspid or molar should always be considered as a sufficient indication for the removal of the tooth. Fourth, irregularity in the arrangement of the teeth, arising from. disproportion between the size of the teeth and the size of the alveo- lar arch, usually requires for its correction the extraction of some one or more teeth. But Avith regard to the teeth most proper to be re- EXTRACTION OF TEETH. 389 moved, the reader is referred to the chapter on irregularity, where he will find full directions for the management of such cases. Fifth, all dead teeth and roots of teeth Avhich act as irritants, and teeth which have become so much loosened from the destruction of their sockets as to be a constant source of disease to the adjacent parts; or teeth otherwise diseased, that are a cause of neuralgia of the face, dis- ease of the maxillary sinus, dyspepsia, or any other local or constitu- tional disturbance, such teeth should, as a general rule, be extracted. There are other indications Avhich call for the extraction of teeth, but the foregoing are among the most common ; they will be found sufficient, in most instances, to determine the propriety or impropriety of the operation. Cases are, hoAvever, continually presenting them- selves, to Avhich no fixed rules would be found applicable, and where an experienced judgment alone can determine the practice proper to be pursued. In conclusion, it is scarcely necessary to say, that whenever a tooth can be restored to health, it should always be done; but tampering with such as cannot be rendered healthy and useful, and which, by remaining in the mouth, exert a deleterious influence, not only upon the adjacent parts, but also upon the general health, cannot be too strongly deprecated. INSTRUMENTS EMPLOYED IN THE OPERATION. Different operators employ different instruments. For about fifty years, the key of Garengeot was almost the only instrument used in the performance of the operation ; but this has in a great measure been superseded by forceps, which, Avhen properly constructed, are far preferable; yet as the key is still used by some, and by them is con- sidered, in certain cases, a valuable instrument, a brief description of it is here given. KEY INSTRUMENT. "The common tooth-key," says Dr. Arnot, "may be regarded in the light of a wheel and axle; the hand of the operator acting on two spokes of the wheel to move it, while the tooth is fixed to the axle by the claAV, and is drawn out as the axle turns. The gum and alveolar process of the jaAV form the support on Avhich the axle rolls." Different dentists have their keys differently constructed, but the principle upon whichxthey all act is precisely the same. Some prefer the bent shaft (Fig. 135), others the straight. Some give a decided preference to the round fulcrum, others to the flat; and though the success of the operator depends greatly upon the perfection of the instrument, yet he may remove a tooth more expertly by means of a 390 EXTRACTION OF TEETH. key Avith which he is familiar, than one to which he is unaccustomed, though its construction be even better. Fig. 135 represents a key with bent shaft and two hooks, one for molars and the ether for bi- cuspids. The author has tried almost every variety of key instrument that has been used in this coun- try, and thinks the straight shank, with a small round fulcrum slightly flattened on each side, decidedly preferable to any other. The objection raised by some to the use of such a key, that it is liable to interfere with the front teeth, is without good foundation. It can be used with as much safety as a key of any construction, and in most cases can be as easily applied. The round is certainly preferable to the flat Tulcrum, because it is less liable to injure the gums and the alveolus. In size it should be a little larger than a half-ounce bullet. Every key instrument should be supplied with several hooks, differ- ing in size, to suit the teeth upon which they are to be applied. The hook described by Dr. Maynard * is preferable to any Avhich the author has seen. It very nearly resembles the eagle's claw, except that its curvature is rather greater. The edge of the hook is about the sixteenth of an inch in width, and divided into tAvo points by a shallow notch. A hook of this description is less liable to slip, and can be more readily applied to a tooth than those ordinarily used. With regard to the merits of the key instrument, or of any other instrument having the same principle of action, as compared Avith the forceps presently to be described, the author does not entertain a very high opinion. The following remarks, quoted from the late Avork of M. Desirabode, accord with the vieAVS which he has. held and promul- gated for many years: " One of the most common causes of fracture of the alveoli is a badly performed operation in the mouth ; although not a very flattering acknoAvledgment for our art, it is necessary to say it. If it be necessary to specify causes, we Avould not hesitate to name, in the first place, the use of the key of Garengeot; for we shall prove, in treating of the extraction of teeth, that this dangerous implement, which is only fit to mask the unskilfulness of the operator, is one of * See Am. Jour. Dent. Sci., No. 3, vol. iii. EXTRACTION OF TEETH. 391 the most defective of surgical instruments; and no practitioner of good sense, being convinced of its mode of action, would attempt to use it even to extract a nail from a board, if he did not desire to break the surrounding material." Perhaps this condemnation is too SAveeping. The principle of action of the key is in fact not unlike that of a nail drawer or tack puller, and is Avell adapted to a certain class of cases; namely, where one wall, either the inner or outer, is decayed below the alveolus, while the opposite one is still standing. The fulcrum, with a folded napkin or other soft substance interposed, is placed against the gum on the side of the tooth most decayed, and the hook adjusted to the neck of the tooth on the opposite side. MANNER OF USING THE KEY INSTRUMENT. The directions required for the use of the key are few and simple, but, as cases frequently occur to which no general rules can be applied, much will depend 6n the practical judgment and surgical tact of the operator. The first step to be taken in the operation is to separate the gum from the neck of the tooth,.down to the alveolus; this should be done, not on two sides only, but round the entire tooth. For this purpose suitable lancets should be provided. A straight, narrow- bladed knife, pointed at the end, and with one cutting edge, will be found most convenient for performing the operation on the approximal sides ; it may be most effectively used by passing the point of the knife between the neck of the tooth and gum, down to the alveolus, Avith its back dowmvard, then cutting in the direction of the croAvn. In this way the connection of the gum to the sides of the neck of the tooth may be thoroughly severed. The same kind of knife, or a com- mon gum-lancet, may be used for separating the gum from the remaining sides of the tooth. If the gum is not Avell separated, there will be danger of lacerating it in the removal of the tooth. After the tooth has been thus prepared, the key, with the proper hook attached, should be firmly fixed upon it; the fulcrum, on the inside, resting upon the edge of the alveolus, the extremity of the claw on the opposite side, pressed down upon the neck. The handle of the instrument is then grasped Avith the right hand, and the tooth raised from its socket by a firm, steady rotation of the wrist. The claw should be pressed down with the forefinger or thumb of the left hand of the operator, until, by the rotation of the instrument, it becomes securely fixed upon the tooth. This precaution is necessary to prevent it from slipping, an accident that frequently happens, and one that is always more or less embarrassing to the dentist. If the tooth is situated on the left side of the mouth, the position of the operator should be at the right side of the patient; but, if it be on 392 EXTRACTION OF TEETH. the right side, he should stand before him. For the removal of a tooth on the left side of the lower jaw, or the right side in the upper, the palm of the hand should be beneath the handle of the instrument; in the extraction of one on the right side of the lower jaw, or on the left side in the upper, it should be above. The manner of grasping the instrument is of more importance than many suppose. If impro- perly held, the operator loses, to a great extent, his control over it. The directions here given are, in some respects, different from those laid down by other writers; but Ave are convinced, from much experi- ence, that they will be found more conducive to the convenience of the operator and the success of the operation than those usually given for the use of this instrument. There is a diversity of opinion as to AAThether a tooth should be re- moved iiiAvardly or outAvardly. Some direct the fulcrum of the instru- ment to be placed to the outside of the tooth, others to the inside, while others again regard it as of little importance on which side it is placed. Experience has taught us that it should, in the majority of cases, be placed on the inside, especially of the lower teeth, as they almost ahvays incline toward the interior of the mouth. Moreover, the edge of the alveolus is usually a little higher on the exterior edge of the jaAV than on the interior; so that the first motion of the instrument, with its fulcrum on the outside, brings the side of the tooth against its socket; thus nearly double the amount of poAver is required to remove it, Avhile, at the same time, the pain and the chances of injury to the alveolar processes are very much increased. It is, hoAvever, frequently necessary to place the bolster of the key on the outside of the tooth; Avhen, for instance, it is decayed in such a way as not to afford a sufficiently firm support for the claAV of the instrument. But, whenever it is possible to remove a tooth inwardly, it should be done. The alveolar walls of the upper teeth are, gener- ally, thinner than those of the lower, and do not afford so strong a support to the fulcrum of the instrument. FORCEPS. Forceps were not very generally or extensively employed, except for the extraction of the front teeth, until about the year 1830; but the improvements made in their construction since that period are so great, that their use has now, among dentists, superseded that of the key. The forceps formerly used were so awkwardly shaped; and so badly adapted to the teeth, that the extraction of a large molar Avith an in- strument of this description was regarded as exceedingly difficult, and even dangerous; even its practicability was doubted by many of the EXTRACTION ,OF TEETH. 393 most experienced practitioners, and hence the key Avas almost the only instrument resorted to for the purpose. When we consider the strong prejudice that so recently existed against the use of forceps, it is not at all wonderful that their employ- ment should have been resorted to with caution. Nor is it surprising that a gentleman of Mr. Bell's intelligence and practical experience should, so late as the period of the publication of the first edition of this work, 1830, tell us that the key is the only instrument to be relied upon for the removal of teeth that are much decayed ; and that those Avho have heaped the most opprobrium upon it are glad to have a concealed recourse to its aid. This may have been true at the time Mr. B. Avrote, but not now. On the contrary, cases are daily occurring of the extraction of teeth with forceps, upon Avhich the key had been previously unsuccessfully employed. It is generally supposed that a greater amount of force is necessary to remove a tooth with forceps than Avith the key, but this is a mistake. It does not ordinarily require as much. The leverage gained by the action of the key is more than counterbalanced by the greater amount of resistance encountered in the lateral direction of the force exerted in the removal of the tooth by that instrument. But with forceps, the direction of the poAver being in the line of the axis of the tooth, an amount sufficient to break up the connection Avith the sockets and to overcome the resistance of the Avails of the alveolus is all that is required. The author has used forceps exclusively since 1834, and he does not hesitate to affirm that any tooth can be extracted with them that can'be removed Avith the key; and that, too, in the majority of cases, Avith greater ease to the operator and less pain to the patient. In order that forceps may be used Avith ease, it is necessary they should be properly constructed. Every operator should possess a number of pairs (nine at least), each Avith a differently shaped beak, adapted to the necks of the teeth to which they are respectively designed to be applied. The improvements made in the shape of the beaks of the upper and lower molar forceps, by Mr. Snell, are very valuable; to Avhich he is entitled to much more credit than the profession generally have ac- corded. For the upper molars two (Fig. 136) are required, one for each side, curved just beloAv the joint, so that the beak shall form an angle of twenty or twenty-five degrees Avith the handles, just enough to clear the lower teeth. The inner blade is grooved to fit the neck of the palatine root; the outer blade has tAvo grooves, Avith a point in the centre to fit the depressions just below the bifurcation of the two buccal roots. Another valuable improvement of his consists in having 391 EXTRACTION OF TEETH. one of the handles bent so as to form a hook. This passes round the operator's little finger, to prevent the hand from slipping. Fig. 136. Fig. 137 represents another form of superior molar forceps, right and left, with a greater curvature in the handles than the Harris pattern, which many consider an improvement. Fig. 137. The handles should be wide, and large enough to prevent them from springing under the grasp of the hand, to Avhich they should be accu- rately fitted. Every dentist, therefore, in having forceps manufac- tured, should give special directions with regard to their shape and size. The beak should be bent no more than is absolutely necessary to prevent the handles from coming in contact with the teeth of the lower jaw ; for in proportion to the degree of curvature will the mus- cular power of the operator be disadvantageously exerted. Each blade of the beak of the lower molar forceps has two grooves, with a point in the centre, so situated that in grasping the tooth it EXTRACTION OF TEETH. 395 comes between the two roots just at the bifurcation. Mr. Snell em- ployed two pairs for the extraction of the lower as well as for the upper molars, in order, as he said, to have a hook to turn round the little finger, which he supposed must be on opposite sides of the instrument. But this is rendered unnecessary by an improvement made by the author in 1833, which consists in having the handles of the instrument so bent that it may be as readily applied to one side of the mouth as the other, while the operator occupies a position to the right and a little behind the patient. By this improvement, the necessity for two pairs is wholly superseded; it, moreover, enables him to control the head of the patient with his left arm and the lower jaw with his left hand, rendering the aid of an assistant Avholly unnecessary. The shape of the instrument, as improved by the author, is shown in Fig. 138. It is now used by many hundreds of operators, Avho prefer it to any other instrument they have ever employed. When applied to a tooth, the handles turn tOAvard the operator, at an angle of about twenty-five or thirty degrees. Without this curvature in the handles, the arm of the operator would often be throAvn so far from his body as to prevent the proper control over the instrument. It is also important that the handles should be Avide and accurately fitted to the hand. Fig. 138. Fig. 139 represents Wolverton's inferior molar forcep for either side, Avith longer points in the centre of each blade of the beak. Fig 139. 396 EXTRACTION OF TEETH. Fig. 140 represents inferior molar forceps for the right and left sides of the mouth, which some prefer to the single forcep. Fig. 140. Fig. 141 represents a lower molar forcep with plain beaks, for use on either side. Fig. 141. For the extraction of the upper incisors and cuspids, one pair only is necessary. (Fig. 142.) These should be straight, Avith grooved or crescent-shaped jaAvs, accurately fitted to the necks of the teeth. The beaks should also be thin, so that they may be easily introduced under the gum, up to the edge of the alveolus. And, like the superior and inferior molar forceps, the handles should be large enough to prevent them from springing in the hand of the operator, with a hook formed at the end of one of them. Fig. 142. For the extraction of the lower incisors, a pair of very narrow- beaked forceps are necessary, to prevent interfering with the teeth ad- joining the one to be removed. The beak below the joint of the EXTRACTION OF TEETH. 397 instrument should be bent downward at an angle of about tAventy-five degrees with the handles. (Fig. 143.) This is also a very valuable instrument for the extraction of the roots of teeth. Fig. 143. An instrument similarly shaped, but with the beak much longer, makes one of the most universally applicable instruments that can be devised. (Fig. 144.) The beak should be made strong, but very narrow. Fig. 144. Fig. 145 represents an inferior incisor hawk-bill forcep, which is a very convenient instrument for the removal of these teeth. It is also used for the removal of the lower cuspids. Fig. 145. Forceps for the extraction of bicuspids should have their jaws so bent as to be easily adapted to these teeth ; they should be narrow, and have a deeper groove on the inside than those for the upper incisors and cuspids; like them, they should be thin, yet strong enough to sustain the pressure which it may be necessary to apply. One pair will ansA\rer for the right and left bicuspids of the upper jaw. (Fig. 146.) For the removal of the cuspids and bicuspids of the lower jaAV, the haAvk's-bill forcep (Fig. 145), with crescent-shaped beaks, is often employed; but the instrument represented in Fig. 147 is, Ave think, better suited to the extraction of these teeth, and can be more conve- 398 EXTRACTION OF TEETH. niently applied. No separate instrument, therefore, is required for the removal of the inferior cuspids. Fig. 14G. may be more conveniently employed for the removal of the upper wisdom teeth. The beak of these is bent above the joint, forming Fig. 148. nearly two right angles, as shoAvn in Fig. 148. These forceps were, we believe, invented by Dr. Edward P. Church,* about the year 1830, * Dr. Church was an ingenious and talented man, and during the four years of his brief professional career he acquired a reputation for skill which few, in so short a time, have been able to achieve; had his life been spared, he would soon have ranked among the very first practitioners in the country. Born in the western part of the State of New York, he chose the Mississippi Valley ns the field of his professional labors, intending ultimately to locate in Cincinnati; but while on a visit to his family, in 1832, he fella victim to the Asiatic cholera, in the twenty-sixth year of his age. EXTRACTION OF TEETH. 399 and in those cases where the superior dentes sapientise are consid- erably shorter than the second molars, they can be successfully and advantageously employed; and indeed, in many cases, they cannot be reached with any of the above described extracting instruments. The handles of these, as of all other forceps, should be no longer than is absolutely necessary for the accommodation of the hand of the operator. For the removal of the inferior dentes sapientise, the forcep repre- sented in Fig. 138, Harris's pattern, or the ones represented in Figs. 140 and 141, may be employed. Fig. 149 represents Physick's dentes sapiential for either side, which is used as an elevating forcep. Fig. 149. For the removal of the roots of teeth, the inferior incisor forceps, represented in Figs. 143 and 144, are very useful; also the forms repre- sented in Figs. 150 and 151. Fig. 150. Fig. 151. Figs. 152, 153, 154, 155, and 156 represent Parmley's patterns of alveola forceps for cutting through the alveolar process to the roots of the teeth. Fig. 157 represents a forcep for separating the diverging roots of molar teeth. There is scarcely any instrument used in dentistry that has called 400 EXTRACTION OF TEETH Fig. 152. Fig. 153. Fig. 154. Fig. 156. Fig. 157. EXTRACTION OF TEETH. 401 forth more ingenuity in devising various shapes than forceps. Almost every practitioner has some peculiar pattern of his o.vn, which will accomplish what no other can. Doubtless many of these instruments are very excellent; but it often happens that an inventor learns, by dint of practice, to do with some pet forceps pf his own contrivance what might as easily have been done with a simpler one already in use. We would not, however, be understood as saying that patterns in present use admit of no improvement. What we do assert is, that skill in the use of a few instruments is preferable to crowding one's case with an unnecessary number. MANNER OF USING THE FORCEPS. In describing the manner of using these instruments, Ave shall com- mence Avith the extraction of the incisors of the upper jaw. These are generally more easily removed than any of the other teeth. The use of the gum lancet should generally precede the application of either the forceps or the key. Many dentists object to the opera- tion as unnecessarily inflicting double pain. Some have their forceps made with thin sharp blades so as to sever the gum on two sides in the act of pressing up the instrument. This practice may be admis- sible, perhaps necessary, in certain exceptional cases ; as Avith chil- dren, or nervous persons, Avhom the act of lancing might deter from permitting the operation to be completed. But we are fully satisfied that as a rule it is very objectionable, either in the use of the key or of forceps. After separating the gum from the neck of the tooth, it should be grasped with a pair of straight forceps (Fig. 142), and pressed several times, in quick succession, outward and inward, giving it at the same time a slight rotary motion, Avhich should be continued until it begins to give way; then, by a slight downward pull, it is easily re- moved. If the tooth is much decayed, it should be grasped as high up under the gum as possible, and no more pressure applied to the handles of the instrument than may be necessary to prevent it from slipping. Teeth are often unnecessarily broken by not attending to this precaution. The same directions will, in most cases, be found applicable for the removal of a lower incisor. But the arrangement of these teeth is sometimes such as to render their extraction rather more difficult. The forceps best calculated for their removal are represented in Figs. 143 and 145. For the extraction of a cuspid, more force is usually required than for the removal of an incisor, because of the greater size and length of its root. The straight forceps (see Fig. 142) should be employed for the removal of the superior, and the curved-beaked forceps (Figs. 2G 402 EXTRACTION OF TEETH. 143 and 147) for the inferior cuspids. In the extraction of these teeth, less rotary motion should be given to the hand than in the removal of the incisors: in every other respect, the operation is per- formed in the same manner. The inferior cuspids usually have longer roots, and are more difficult to remove than the superior. Very little rotary motion can be given to a bicuspid, especially an upper one, in its extraction. After it has been pressed outward and inward several times, or until it begins to give way, it should be re- moved by pulling in the direct line of its axis. For the extraction of the upper, the forceps represented in Fig. 142, and for the lower, those represented in Fig. 147, are the proper instruments to be employed; unless the crown has become so much weakened by decay that it will not bear the requisite amount of pressure. In this case, the gum on each side should be separated from the alveolus about an eighth or three-sixteenths of an inch, and slitted so as to permit the application of the narrow-beaked forceps, Fig. 143. With these, the alveolar wall on each side may be easily cut through, and a sufficiently firm hold obtained upon the root of the tooth for its removal. These forceps will also be found better adapted for the removal of the molars, when in a similar condition, than any other instrument. The upper molars, having three roots, generally require a greater amount of force for their removal than any of the other teeth. They should be grasped as high upas possible, Avith one of the forceps repre- sented in Fig. 136 or 137, and then pressed outward and inward, until the tooth is well loosened, when it may be pulled from the socket. If the forceps used for the extraction of the upper molars are of the right description and properly applied, they will be found the safest and most efficient instruments that can be employed for their removal. The superior dentes sapientise are usually less firmly articulated to the jaw than are the first and second molars; they are therefore more easily removed. When their crowns are sufficiently long to admit of being grasped with the bicuspid forceps (Fig. 146), they should be removed with this instrument; but when this cannot be applied with- out interfering with the anterior teeth, the forceps represented in Fig. 148 may be substituted. The inferior molars, although they have but tAvo roots, are often very firmly articulated, and require considerable force for their re- moval ; and it sometimes happens that, when the approximal side of one has been destroyed by caries, the adjoining tooth has impinged upon it in such a manner as to constitute a formidable obstacle to its extraction. Two teeth are often removed in attempting to extract one thus situated, unless the precaution is taken of filing off the side of the encroaching tooth. This should never be omitted in the extraction of a EXTRACTION OF TEETH. 403 lower molar or bicuspid locked in the manner just described. It sometimes, though less frequently, happens that the upper teeth im- pinge upon each other in the same manner; in this case, also, the adjoining tooth should be filed sufficiently to liberate the one that is to be extracted before attempting its removal. In applying forceps to an inferior molar, the points on the beak of the instrument should be forced doAvn betAveen the roots ; after having obtained a firm hold, the tooth should be forced outAvard and inward several times in quick suc- cession, until its connection with the jaw is partially broken up, and then raised from the socket. If the tooth has decayed down to the neck, the points of the beak may include the upper edge of the alve- olus, through which they will readily pass, on applying pressure to the handles, and in this manner a secure hold Avill be obtained upon the tooth. The same should also be done in the extraction of a superior molar in this condition. The dentes sapientise in the loAver jaw, when situated far back under the coronoid processes, are oftentimes exceedingly difficult to extract; but Avith forceps like those represented in Fig. 143 they may always be grasped by an expert operator, except in those cases where their crowns have been destroyed by caries, Avhen a portion of the alveolus should be cut away, either with forceps or a strong sharp-pointed instrument, previously to attempting their removal. It occasionally happens that the roots of these teeth are bent in such a manner as to constitute a considerable obstacle to their removal. But Avhen this is the case, the roots are almost always turned posteriorly toward the coronoid processes ; so that after starting the tooth, if the operator is unable to lift it perpendicularly from the socket, he will haA^e reason to suspect its retention to be OAving to an obstacle of this nature. To overcome this, as he raises his hand, he should push the crown of the tooth backAvard, making it describe the segment of a circle; for should he persist in his efforts to remove it directly upAvard, the root will be broken and left in the jaw. Fig. 149 represents an elevating forcep useful in removing the dentes sapientise when they are but partially erupted or badly decayed. It sometimes happens that the roots of the first and second molars of both jaws, and those of the superior dentes sapientise, are bent, or else diverge or converge so much as to render their extraction exceed- ingly difficult. The convergency of these roots is often so great that; in their removal, the intervening wall of the alveolus is brought aAA'ay; but neither from this, nor from the removal of a portion of the ex- terior wall, will any unpleasant results follow. Similar malformations are occasionally met with in the roots of the bicuspids, the cuspids, and even the incisors. 404 EXTRACTION OF TEETH. Other obstacles sometimes present themselves in the extraction of teeth, which the judgment and tact of the operator alone will enable him to overcome. The nature and peculiarity of each case Avill sug- gest the method of procedure most proper to be pursued. The dentist should never hesitate to embrace a portion of the alveolus betAveen the jaAvs of the forceps, when necessary to enable him to obtain a firm hold upon the tooth. The removal of the upper edge of the socket is never productive of injury, as it is always subsequently removed, more or less rapidly, by the process of absorption. When the crown of a tooth has become so much weakened by disease that it Avill not bear the pressure of the instrument, it may be removed in this manner without inflicting upon the patient half the pain that would be caused by the attempt to spare the thin, perishable alveolar Avails. MANNER OF EXTRACTING ROOTS OF TEETH. The extraction of roots of teeth is sometimes attended with con- siderable difficulty; but generally they are more easily removed than the whole teeth, especially the roots of the molars; for, after the de- struction of their crowns, an effort is usually made by the economy to expel them from the jaAvs. This is done by the gradual absorption of the. alveolus, together with the filling up of the socket by a depo- sition of ossific matter at the bottom; whereby the articulation of the root becomes weakened, and its removal rendered proportionably easier. The alveolar cavities are often wholly obliterated in the course of two or three years after the destruction of the crowns of the teeth, and the roots retained in the mouth, simply by their connection with the gums; so that for their removal little more is necessary than to sever this bond of union with a lancet or sharp-pointed knife. The instruments usually employed in the extraction of roots of teeth are the hook, punch, elevator, and screw, all of Avhich are rep- resented in Figs. 158 and 159. Although every dentist has them made to suit his own peculiar notions, the manner of using them, and the principle upon which they act, are the same. It will, therefore, be sufficient to say that they should be of a convenient size, made of eood steel, and so tempered as neither to bend nor break. Fig. 158. EXTRACTION OF TEETH. 405 The hook a, Fig. 158, is chiefly used for the extraction of the roots of molar and bicuspid teeth on the left side of the mouth ; the punch Fig. 159. b, Fig. 158, for the removal of those on the right side; the elevator c, Fig. 159, for the extraction of roots on either side, as occasion may require ; and the screw d, Fig. 159, for the removal of those of the upper front teeth. Considerable tact is necessary for the skilful use of these instru- ments, and this can only be obtained by practice. Great care is requi- site in using the punch and elevator to prevent them from slipping, and injuring the mouth of the patient. Whenever, therefore, either of these are used, the forefinger of the left hand of the operator should be wrapped Avith a napkin and placed on the side of the root opposite to that against which the instrument is applied, so as to catch the point in case it should slip. But for the removal of the roots of bicuspids and molars, and often for those of the cuspids and incisors, the narrow-beaked forceps, recom- mended for the extraction of the lower incisors (see Fig. 143), may be used more effectively than any other instrument. When the root is decayed down to the alveolus, the gum should be separated from it, and so much of it as may be necessary to obtain a secure hold upon the root included between the beaks of the forcep; for these, being very narroAV, readily pass through the alveolus, and a firm hold is at once obtained upon the root; then, after moving it a few times, out- ward and inward, it may easily be removed from its socket. There are some cases, however, in which the punch, hook, and ele- vator may be advantageously used. We have also occasionally met Avith cases Avhere we have succeeded in removing roots of teeth Avith great ease by means of an elevator shaped like the blade of a knife, first forcing it into the socket by the side of the root, and then turning it so as to make the back press against the former and the edge.against the latter. When this instrument, represented in Fig. 160, is used, the blade should not be more than an inch in length, and it should be straight, short at the point, and have a very thick back, that it may 408 EXTRACTION OF TEETH. not break in the operation. In using the common elevator, it is neces- sary that there should be an adjoining tooth or root to act as a fulcrum. Fig. 160. When this can be employed, a root, or even a wThole tooth, .may some- times be removed with it; but, as a general rule, forceps should be preferred to any of these instruments. For the extraction of the roots of the upper front teeth, after they have become so much funnelled out by decay as to render their walls incapableof sustaining the pressure of forceps, the conical screw is inval- uable. With this a sufficiently firm hold for the removal of the root can be obtained by screwing it into the cavity. But before it is intro- duced, the soft decomposed dentine should be removed from the inte- rior of the root with a triangular-pointed instrument like the one represented in Fig. 161. Fig. 161. Dr. S. P. Hullihen has invented a most valuable and useful instru- ment for the removal of the roots of the superior incisors and cuspids when in the condition just described. It combines the advantages both of the screw and forceps, as may be seen by the accompanying cut. It is thus described by the author: "Lengthwise, within, and between the blades of the beak is a steel tube, one end of which is open, the other solid and flat, and jointed in a mortice in the male part of the joint of the forceps. When the forceps are opened, this joint permits the tube to fall backward and forward from one blade of the beak to the other, without any lateral motion. Within this tube is a spiral spring, which forces a shaft up two-thirds of the tube, the other part is a well-tapered or conical screw. . . The shaft and tube are so fitted together, and to the beak of the forceps, that one- half of the rounded part of the shaft projects be- yond the end of the tube, so that the shaft may play up and doAvn upon the spring about half an inch, EXTRACTION OF TEETH. 407 and the screAV or shaft be embraced between the blades of the beak of the instrument." Dr. Hullihen's instrument is represented in Fig. 162. "The forceps," says Dr. H, "are used by first embracing the shaft between the blades.* Then screAving it as gently and deeply into the root as possible, the blades are opened, and pushed up on the root, Avhich is then seized and extracted. The screAV thus combined with the forceps, prevents the root from being crushed. It acts as a powerful lever when a lateral motion is given; it is likewise of advantage Avhen a rotary motion is made; it prevents the forceps from slipping or from losing their action should one side of the root give Avay in the act of extracting it; and is used with equal advantage where one side of the root is entirely gone." The opportunities which the author has had of testing the value of this instrument, have been sufficient to justify him in stating that its merits are not overrated by the inventor. Every practitioner Avould, therefore, do well to provide himself with one of them. Fig. 163. Fig. 163 represents Dubs' screw forceps: 1. Conical screw, with square ratchet shaft. 2. Beaks of forceps, grooved inside. 3. Socket, with square hole to receive shaft. 4. Spring trigger, by Avhich the sci-cav can be detached at pleasure at any given point. For the extraction of the roots of the upper molars, before they have become separated from each other by decay, the forceps (Fig. 164), invented by Dr. Maynard, will be found highly valuable. The outer beak of each instrument is brought to a sharp point, for per- forating the alveolus between the buccal roots, and for securing between them a firm hold, Avhile the inner beak is intended to rest upon the edge of the alveolus and embrace the palatine root. By this means a sufficiently firm hold is secured to enable the operator to remove the roots of an upper molar without difficulty. Two pairs, as represented * The author has a pair constructed so that the blades of the beak of the forceps grasp the upper extremity of the screw instead of the shaft. 408 EXTRACTION OF TEETH. Fig. 164. in the engraving, one for the right and one for the left side, are re- quired. The advantage to be derived from forceps of this description must be apparent to every dentist. EXTRACTION OF THE TEMPORARY TEETH. The temporary teeth should be extracted in the same manner as the permanent, and with the same instruments. If the power be properly directed, very little force is required for their removal ; because the roots of these teeth have generally suffered more or less loss of sub- stance before the operation is called for; and when they remain, the alveolar processes, at this early age, are so soft and yielding as to offer little resistance to the tooth. The operator should be careful not to injure the pulps of the perma- nent teeth, or the jaw-bone. Serious accidents sometimes occur from an improper or awkward removal of these teeth. But, as has been before remarked, their-extraction is seldom required. It should only be resorted to for the relief of toothache, the cure of alveolar abscess, to prevent irregularity in the permanent teeth, or in case of necrosis of the socket*. And even in such cases it is necessary to exercise much judgment in deciding how far pain and inconvenience should be en- dured rather than extract the offending tooth ; or how far the chance of injury to the permanent teeth demands the removal of the diseased milk teeth. Their premature extraction is so often followed by a croAvded state of the permanent teeth, that their indiscriminate removal, for trifling causes, cannot be too strongly condemned. HEMORRHAGE AFTER EXTRACTION. It rarely happens that excessive hemorrhage folloAvs the extraction of a tooth. Indeed, it is oftener more desirable to promote bleeding EXTRACTION OF TEETH. 409 by rinsing the mouth with Avarm Avater than to attempt its suppression. Nevertheless, cases do sometimes occur in which it becomes excessive and alarming. It has been knoAvn, in some instances, to terminate * fatally ; this, however, does not appear to be dependent upon the man- ner in Avhich the operation is performed, but rather upon a hemor- rhagic diathesis of body, attributable to a deficiency in the coagulating property of the blood. Hence, whenever a tendency to it exhibits it- self in one member of a family, it is usually found to exist in all. Of the many cases which have fallen under our own observation, we shall mention only the following : In the fall of 1834, Miss I., fifteen years of age, had the second molar on the left side of the upper jaw removed. The hemorrhage, immediately after the operation, was not greater than usually occurs, and in the course of half or three-quarters of an hour it ceased alto- gether. But at about twelve o'clock on the folloAving night it com- menced again, the blood floAving so profusely as to excite considerable alarm. A messenger was immediately sent to ask our advice, and we directed that the alveolar cavities should be filled with pledgets of lint, saturated with tincture of nutgalls. Two days after, at about six o'clock in the morning, Ave were hastily sent for by the young lady's mother, and when we arrived at her residence, we were informed that the bleeding had then been going on for about four hours. During this time more than two quarts of blood had been discharged. The blood Avas still oozing very fast. After we had removed the coagulum, Ave filled the socket with pieces of sponge, saturated, as the lint had been, with tincture of nutgalls. When firmly pressed in, and secured by a compress, the hemorrhage ceased. These Avere permitted to remain until they Avere expelled by the suppurative and granulating processes. We afterward had occasion to extract one tooth for a sister, and tAvo for the mother of the young lady, and a hemorrhage, similar to that just described, occurred in each case. We have had perhaps some thirty or forty cases of this description, but never found it necessary, except in one instance, to adopt any other course of treatment than that described in the case just narrated. More poAverful remedies, hoAvever, are sometimes employed. Some use a solution of the sulphate of copper, or of the nitrate of silver, while others employ the actual cautery. Tannic acid is an excellent styptic, and Avill ansAver well in combination with the compress of lint or cotton for most cases. For more obstinate cases the persul- phate of iron will be found to be the most potent styptic of the ma- teria medica. But if pressure be so applied as to act directly upon the mouths of the bleeding vessels, it will almost always arrest the * 410 USE OF ANESTHETIC AGENTS. hemorrhage. The author has, in two cases, found it necessary to have recourse to the actual cautery. The following case is quoted by Dr. Fitch, from " Le Dentiste Ob- servateur, par H. G. Courtois," Paris, 1775: " A person living in Paris called on me to extract a canine tooth for him. On examining his mouth, I thought that the man was attacked with scurvy ; but this did not seem sufficient to hinder the patient from having his tooth extracted; nor would he consent to its remaining, on account of the pain which it gave him. After the tooth was extracted, it did not appear to me that it bled more profusely than is customary after similar operations. The following night I was called upon to see the patient, who had continued to bleed ever since he left me. I employed, for stopping this hemorrhage, agaric from the oak bark, which I commonly used with success. The following day I was again sent for; the bleeding still continued. After having disbur- dened the mouth of all the lint-pledgets, which I used for making compression at the place Avhere the blood appeared to come from, I made the patient take some mouthfuls of water to clear his mouth of all the clots of blood with which it was filled; I perceived then that the blood came no longer from the place where I had extracted the tooth, but from the gums ; there was not a single place in the whole mouth from which the blood did not issue. I called in the physician, Avho ordered several bleedings in succession, besides astringents, taken internally, and gargles of the same nature ; but all these attempts to improve the coagulability of the blood were made to no purpose. It Avas not possible to stop the hemorrhage. The patient died the ninth or tenth day after the extraction of the tooth." Mr. Snell mentions a similar case, which also terminated fatally. CHAPTER VII. THE USE OF ANAESTHETIC AGENTS IN THE EXTRACTION OF TEETH. OF the various agents that have been employed for the prevention of pain during surgical operations, sulphuric ether and chloroform have proven more successful and been more generally used than any others. The practicability of producing ansesthesia with ether Avas first demonstrated by Dr. Horace Wells, of Hartford, Conn., in 1846, and soon afterward brought prominently before the medical and dental *» USE OF ANAESTHETIC AGENTS. 411 professions by Dr. W. G. S. Morton, of Boston, Mass., both practical dentists; and with chloroform, in 1847, by Prof. J. Y. Simpson, of Edinburgh, Scotland. The ausesthetic effect is obtained by inhalation of the vapor, and is supposed to be nothing more than a transient state of intoxication, which usually disappears almost immediately after the discontinuance of the administration, though in many cases it has proved fatal. For this reason, we do not think that agents capable of producing such powerful and dangerous effects as ether and chlo- roform should be used in so simple an operation as the extraction of a tooth. The first, however, is less dangerous than the second; but its anaesthetic effect is less certain and prompt, from seven to ten minutes being usually required, whereas, Avith the other, it is obtained in from thirty seconds to tAvo minutes. When ether is used, from six to ten or fifteen ounces are employed ; but with chloroform, it is rarely necessary to administer more than from thirty to one hundred and fifty drops. What we have said about sulphuric ether applies equally to chloric ether, a substance very extensively used, if not first proposed, by the late Prof. Warren, of Boston. A number of instruments have been gotten up for the inhalation of the vapor of these agents; but the simplest and, we think, the best method of administration is from a hollow sponge, a napkin, or a pocket-handkerchief. It may not always be possible for any one, in-the administration of either of the foregoing agents, even to a person supposed to be free from any special proclivity to disease from organic derangement, to pronounce, a priori, that no bad effect will result from it; but all agree that it is unsafe to give it to a patient laboring under disease of the heart, brain, or lungs. The practitioner, therefore, whether medical or dental, should be Avell assured, before giving ether or chlo- roform, and especially the latter, that these organs are not only free from disease, but also from any morbid tendency, as ignorance with regard to this matter might lead to fatal consequences. It should be given cautiously under any circumstances, and the pulse should never be permitted to fall, during the inhalation, below sixty, or, at most, fifty-five beats a minute ; but if from carelessness, or any other cause, the patient should sink and the pulsation cease, the agent should be immediately removed from the mouth, and if occupying a sitting posture, he should be placed in a reclining position, air freely admitted, cold water dashed in the face, the feet and hands rubbed with hot salt or mustard, and, if necessary, artificial respiration made and galvanism applied. In addition to these means the tongue should be depressed and drawn forward by a finger thrust deeply into the mouth, as recom- mended by Ricord; or Dr. Marshall's "ready method" may be faith- 412 USE OF ANESTHETIC AGENTS. fully and patiently practised. Ellis gives the following simplified formula of this method for cases of asphyxia from drowning: " In- stantly place the patient on the face and side, supporting the head. Unfasten the clothes about the neck and chest, braces, etc. Wipe and clean the mouth and nostrils. Raise and support the chest on a folded coat or bundle. Roll the patient constantly and gently from the face to the side, and back again, occasionally changing the side, supporting the head. On the completion of each turn to the face make a brisk pressure on the back, betAveen and below each shoulder- blade. Dry and rub the patient briskly, rubbing upward." It is thought by those who have had most experience in the use of ether and chloroform as ansesthetic agents that their administration is attended with less danger when the patient is in a reclining than when in a sitting posture. It would be well, therefore, Avhen either is used preparatory to the extraction of teeth, to place the patient as nearly as possible in such a position ; when the dentist is provided with an operating chair having a movable back this can be very readily done. The ansesthetic effect of nitrous oxide, or laughing gas, was first suggested by Sir Humphrey Davy, in 1776, and practically demon- strated by Dr. Horace Wells. This gas is manufactured from the salt nitrate of ammonia, either in a fused or granulated *form, by slowly melting and boiling it in a glass retort, over a sand bath, until nearly all of the nitrate is decomposed. The gas, on leaving the retort, passes through several wash bottles, one of which contains either a solution of the sulphate of iron or caustic potash, and the other two pure water, for the purpose of purifying it before it enters a holder and receiver, from Avhich it is administered to the patient by means of an inhaling tube. One pound of the granulated nitrate of ammonia will produce about thirty gallons of the gas, which should be administered to the patient in a pure state — unmixed with atmospheric air. Fig. 165 represents a nitrous oxide gas apparatus. In administering this gas for dental operations, the patient is seated in an operating chair with a movable back, a cork or piece of Avood to which a string is attached placed between the jaAvs, and the mouth- piece of the inhaler between the lips, which he is directed to close tightly around it. The operator, avIio occupies a position on the right side of the patient, supports the inhaler with his right hand, some of the fingers of which press the lower lip tightly about the mouth-piece. The thumb and index-finger of the left hand close the nostrils, Avhile the remaining fingers press the upper lip about the mouth-piece of the inhaler. The patient is then instructed to make long, but at the same USE OF ANESTHETIC AGENTS. 413 time natural, inspirations, one of the valves of the inhaler permitting the exhalations to pass off. Fig. 165. After thus inhaling the gas for a few minutes, its anaesthetic effects are shown by strong involuntary respirations attended by a snoring sound, owing to the relaxation of the muscles of the pharynx. Then folloAvs a livid appearance of the lips, from the discolored blood in the capillaries. A spasmodic twitching of the muscles is observed at this stage in many patients, Avhen complete narcosis follows. The narcotic effects of the gas continue from thirty seconds to one and a half minutes, 414 USE OF ANESTHETIC AGENTS. and the number of teeth which can be extracted varies from four to tAvelve. It is no unusual occurrence, however, for the extraction of one tooth to consume the entire time the patient is under the narcotic influence of the gas, Avhile, in other cases, more than the highest number just mentioned may be removed before the patient becomes conscious to pain. Nitrous oxide gas is considered to be the safest general anses- thetic now in use, and does not produce the nauseating and debilita- ting effects Avhich are often caused by ether and chloroform. Ex- treme caution, however, is necessary in administering this gas under circumstances Avhich prohibit the use of other general ansesthetic agents. The greatest objection to its use, aside from the question of safety, is the rapidity in operating AA-hich its transient effect necessitates; and it is much better to carefully extract a few teeth than to attempt the removal of many by an operation Avhich may be attended with severe laceration of the gums and fracture of the alveolus. Several years since, Dr. B. W. Richardson, of London, introduced an anaesthetic agent, knoAvn as the bichloride of methylene, Avhich is formed by the action of sulphuric acid on zinc in chloroform. It dif- fers, however, from chloroform in the circumstance that one atom of chlorine is replaced by one atom of hydrogen. Bichloride of methy- lene produces as great a degree of insensibility as chloroform, and its action is more rapid and the narcotism very prolonged. It also inter- feres less with muscular irritability than either ether or chloroform, and the recovery from its effects is sudden, but more of it is required. When it destroys life, as it has in several cases, the respiring and cir- culating functions are equally paralyzed. Considerable interest has of late been manifested in an ansesthetic compound knoAAm as the hydrate of chloral. Chloral is by no means a new ansesthetic, Liebig having discovered it in 1830; but, as Dr. B. W. Richardson states, the introduction of it into medicine is a fact of the present year, its introducer being Liebreich, of Berlin. The hydrate is made from the chloral by the simple addition of a little water, and on the application of heat solidifies into a white crys- talline substance. The manner in which hydrate of chloral is administered is in solu- tion Avith Avater, either by the mouth directly into the stomach, or by subcutaneous injection. The best solution is made by mixing one grain of the hydrate with tAvo of Avater. Dissolved in an excess of water, the taste is agreeable, with the odor of a ripe melon. It is administered to human subjects in doses varying from tAventy-five to thirty grains, causing unconsciousness to pain, and a profound sleep lasting over sev- eral hours. The sleep is gentle and quiet, induced Avithout distress, and leaving no other symptom behind except nausea, which is occa- USE OF ANESTHETIC AGENTS. 415 sionally experienced after recovery. In administering this agent, it appears to act more promptly Avhen subcutaneously injected than when administered directly by the mouth ; and as chloral dissolved in water is slightly caustic, it cannot be administered by the mouth when there are lesions of mucous membrane or ulcerated tracts of intestinal canal. In administering hydrate of chloral to the human subject, Dr. Richard- son states that allowance will have to be made not only in relation to size and weight, but to obesity or leanness, to natural habit and actual state of body in respect to sensibility. Fig. 166. Fig. 166 represents the full size of a hypodermic syringe Avith grad- uated rod and steel points. Suspension of nervous sensibility, induced by inhaling the vapor of the above-mentioned agents, is general, every part of the body being affected alike; but partial or local anaesthesia may be procured by other and less dangerous means. Congelation or freezing, first pro- posed and employed in the Charite Hospital, Paris, by an interne of M. Velpeau, and subsequently recommended by Dr. James Arnott, of London, has been resorted to for several years, both by surgeons and dentists, and practised to a limited extent, Avith some success. This may be effected by applying a mixture of pounded ice and com- mon salt, in the proportion of two or three parts of the former to one of the latter, to the part on Avhich the operation is to be performed. But in the use of this, care is necessary to prevent reducing the tem- perature too much, as in this case loss of vitality Avould be occasioned by it. We haAre heard of a few cases in Avhich this has occurred, but Ave believe it was OAving, in every instance, to carelessness or want of judgment on the part of the operator as to the length of time the application of the mixture should be continued. Several instruments have been invented for the application of the freezing mixture to teeth preparatory to extraction. The one which Ave consider best adapted for the purpose Avas designed by Dr. Branch, of Chicago, 111. It consists of a IioIIoav tube about an inch or a little more in diameter, Avith about five-eighths of an inch cut out at one end 416 USE OF ANESTHETIC AGENTS. on either side, that it may readily be placed over a tooth. To this is attached a sac of finely-prepared membrane large enough to hold a table-spoonful of the mixture. The hollow of the tube is occupied by a steel wire spiral spring. Just before using it, a sufficient quantity of the freezing mixture is put in the tube; the end of the latter is placed over the tooth, when the ice and salt are forced up gently around it by pressing on the spring at the other extremity of the instrument. Two tubes are employed, one straight for teeth in the anterior part of the mouth, the other bent near one end for the more convenient application of the mixture to a molar tooth. The sudden application of such intense cold to a sensitive tooth, or to one which has not lost its vitality, is often productive, at first, of severe pain; on this account many object to the use of it, preferring the momentary suffering consequent upon the operation of extraction than that occasioned by the freezing mixture. But this effect is rarely experienced in its use on dead teeth or the roots of teeth which have lost their vitality; hence, the application of it has to such proved more satisfactory than to living teeth. With the view of obviating the above objection to the use of cold as an ansesthetic agent, Messrs. Home- and Thornthwaite, opticians, at the suggestion of Mr. Blundell, dentist, of London, contrived and constructed an apparatus by which the temperature may be gradually diminished ; say from 98°, or blood heat, down to zero, or any required degree, thus preventing the pain consequent upon the sudden applica- tion of the freezing agent. The apparatus is thus described: "The required amount of water is cooled down, by means of ice and salt, to about zero, in a vessel called the refrigerator. To this vessel is attached another, called a graduator, containing Avarm water at about 100°, and so constructed as to allow the sIoav admixture of its contents with the chilled water in the refrigerator, and thus produce a gradually dimin- ishing temperature, for the purpose of preventing sudden shock and pain to the teeth, which a direct application of cold would inevitably cause. A tube conveys this graduating current into a terminal portion constructed of very fine membrane, which adapts itself to the form of the gums, and Avholly surrounds the tooth to be withdrawn. The fluid then passes away through an exit tube. In this manner a constant current of cold, at a decreasing temperature, is made to pass over the part, abstracting therefrom all heat, and Avith it the power of feeling." The gum and alveolar membrane being now in a frozen condition, and, consequently, devoid of sensibility, the extracting instrument is applied and the tooth removed. In the early part of the year 1858, Mr. J. B. Francis, dentist, of Philadelphia, announced the discovery of an original method of pro- USE OF ANESTHETIC AGENTS. 417 during local ansesthesia, said to be peculiarly applicable to the extrac- tion of teeth, which consists in passing an electro-galvanic current through the tooth at the moment of its removal. The discovery Avas submitted to the Franklin Institute, Philadelphia, and the committee to whom it was referred for examination, composed in part of dentists, reported favorably in regard to the claims of the inventor.* One of the members of this committee, W. S. Wilkinson, states that he had extracted between four and five hundred teeth, applying the electric current; and that in ninety-five per cent, of the cases it was done without pain to his patient. The method of applying it is very simple. One pole (the negative is preferable) of the electro-galvanic machine is attached to one of the handles of the forceps by means of a flexible conductor, while the metallic handle of the other is grasped by the patient; the power of the current being previously to the operation graduated by the piston of the coil, while the patient holds the forceps in the other hand. The current should only be sufficiently powerful to be distinctly felt. The circuit through the tooth is not made until at the instant the operation begins. The closing and breaking of the galvanic circuit is managed either by the foot of the operator or by an assistant. A small electro-galvanic battery, arranged for this purpose, having been placed in the office of the author, soon after the announcement of the discovery, he has had frequent opportunities of applying this new agent in the extraction of teeth. Thus far, about nine out of ten of those who were placed under its influence, while undergoing the opera- tion, assured him that they either experienced no pain at all, or only very little — not a tenth part of what they had experienced under the operation on former occasions. In almost every case in which the tooth was grasped, alloAving the instrument to come in contact with only the * The following is an extract from the report referred to above: "The com- mittee is satisfied, from the observation and experiment of its members, that in a large majority of cases of extraction with this apparatus, no pain whatever is felt by the patient. " To test the question whether the effect might not be simply mental, the cir- cuit was broken without the patient being aware of it, when the usual pain was experienced, although, in the same patient, and on the same occasion, teeth had been removed, while the current was flowing, without causing pain. "In the less successful cases, the teeth were broken and diseased below the level of the gum. and the pain, in adjusting the forceps previous to the comple- tion of the circuit and the extraction, was considerable. "The sensation produced by the passage of the current is not painful, it being so adjusted as to he just perceptible to the patient. The committee believes its use to be entirely without danger, and not likely to be followed by any unpleasant after effects." '11 418 USE OF ANESTHETIC AGENTS. edge of the gum, the operation appeared to be painless, or nearly so. But when pushed up a considerable distance betAveen it and the tooth, the suffering was not appreciably diminished, the electric current in such cases seeming to be too much diffused. It is stated by those who have made the experiment, that this diffusion of the electric current may be prevented by insulating the outer portion of the instrument with a coating of gutta-percha, or by japanning. The author has not tried this expedient. How it is that the passage of an electric current through a tooth should prevent pain may be explained by supposing the subtle fluid to exhaust the sensibility of the nerves of the parts comprised in the opera- tion ; and that it does, in a majority of cases, is attested by many Avho have been placed under its influence. It may be nothing more than a mere substitution of one sensation for another; but whether its appli- cation will become general, or its efficacy as an ansesthetic agent be fully established, remains for future experience to settle. The experience of the profession may be briefly summed up thus: In one-fourth the cases it relieves or neutralizes the peculiar pain of extraction, in one-half it has but little effect, and in the remaining fourth it very decidedly aggravates the pain. It has, however, the advantage over chloroform and the freezing process, of being without any serious sequelse. Several years since, Dr. B. W. Richardson, of London, introduced a much more speedy and effectual method of congelation than those before described, by taking advantage of the intense cold occasioned by the rapid evaporation of ether spray when forced through one of the instru- ments invented for the atomization of fluids. " The principle," Dr. Richardson remarks, " consists in directing on a part of the body a volatile liquid, having a boiling point at or below blood heat, in a state of fine subdivision or spray, such subdivision being produced by the action of air, or other gaseous substance, on the vola- tile liquid to be dispersed." " When the volatile fluid, dispersed in the form of spray, falls on the human body, it comes with force into the most minute contact with the surface upon which it strikes." "As a result there is rapid evaporation of the volatile fluid, and so great an evolution of heat force from the surface of the body struck, that the blood cannot supply the equivalent loss." " The part consequently dies for the moment, and is insensible as in death; but as the vis-a-tergo of the body is unaffected, the blood, as soon as the external reducing agency is withdrawn, quickly makes its way again through the dead parts, and restoration is immediate." " The extreme rapidity of the action of this deadening process is the cause of its safety." Fig. 167 represents the apparatus, which consists of a spray-tube, USE OF ANESTHETIC AGENTS. 419 bottle, and hand-belloAvs, for producing local ansesthesia by narcotic spray. Fig. 167. Either absolute ether or rhigolene may be employed, both of which are highly inflammable. Some prefer rhigolene on account of its action being more prompt than that of the ether, Avhile others consider the latter more agreeable and easily controlled. To produce the local ansesthetic effect with these agents in the form of spray requires from thirty to sixty seconds. Before the application of the spray, the croAvn of the tooth to be extracted and mucous membrane over the root should be carefully dried, otherwise a film of ice may be formed which will prevent the full influence of the agent, such as is shown by the blanch- ing of the gum. Local bloodletting, such as follows lancing of the gums, prior to the application of the spray, is said to prevent desquamation. As the use of anaesthetic agents of any kind in the extraction of teeth is attended with inconvenience, nearly ah\Tays delaying the operation, the author is of opinion that their employment, as a general thing, should be dispensed Avith. He never encourages their use, and rarely finds it necessary to employ them. In the case of females with a highly nervous organization, it may noAV and then be advisable to give a tem- porary courage to endure pain by the administration of a teaspoonful of brandy. But we have found less trouble Avith delicate females than with stalwart men ; and to the latter we certainly would never advise this use of stimulants. Indeed, the extraction of a tooth is so simple an operation, seldom requiring more than from two to five seconds for its performance, that most persons should rather submit to it at once, than have it protracted by the application of an agent for the preven- tion of the momentary pain which it occasions. 420 IRREGULARITY OF THE TEETH. CHAPTER VIII. IRREGULARITY OF THE TEETH. PECULIARITIES in the Formation and Growth of the Teeth.—In the development and growth of the various parts of the body, curious and interesting anomalies are sometimes obsen^ed; but in no portion of it are they more frequent in their occurrence or diversified in their character than in the teeth. But aberrations in the formation and groAvth of these organs are, for the most part, confined to the teeth of second dentition. Mr. Fox gives a drawing of a tooth very much resembling the letter S. The malformation was caused by an obstructing temporary tooth. The author has also met with several examples of teeth similarly deformed, and from like causes. The molars of the upper jaw sometimes have four and even five roots, and those of the lower, three, and occasionally four. The crowns of the teeth, also, frequently present deviations from the natural shape equally striking and remarkable. The next peculiarity to be noticed is that of size, and in this respect the teeth are very variable. Even in the same mouth, the Avant of relative proportion between the different classes of teeth is sometimes quite conspicuous. But examples of this kind are not very frequent; for where there is an increase or diminution in the size of the teeth of one class, there is generally a corresponding change in that of the other. Aberrations of this character are probably dependent upon some diathesis of the general system, whereby the teeth, during the earlier stages of their formation, are supplied Avith an excessive or diminished quantity of nutriment. Some very remarkable deviations have been known to take place in the growth of the teeth. The most singular case on record is that related by Albinus. " Two teeth," says he, " between the nose and the orbits of the eye, one on the right side and the other on the left, Avere inclosed in the roots of those processes that extend from the maxillary bones to the eminence of the nose. They Avere large, remarkably thick, and so very like the canines that they seemed to be these teeth, which had not before appeared; but the canines themselves were also present, more than usually small and short, and placed in their proper sockets. The former, therefore, appear to have been new canines, IRREGULARITY OF THE TEETH. 421 which had not penetrated their sockets, because they were situated where these same teeth are usually observed to be in children. But what is still more remarkable, their points Avere directed toward the eyes, as if they were the new eye teeth inverted, And they were also so formed that they Avere, contrary to what usually happens, convex on the posterior and concave on the anterior." A case of a somewhat similar character is mentioned by Mr. John Hunter. The folloAving case is in the words of Mr. G. Wait: " While I was prosecuting my anatomical studies. I was struck Avith the appearance of a cuspid of the upper jaw ; it Avas short, and appeared as if the body of the tooth was in the jaw, and that it was the tip of the root that presented itself. Upon further examination I found this verified, and after the cranium and lower jaw Avere properly macerated and cleansed, I found one of the lower bicuspids in the same position." The author can readily imagine that a cuspid of the upper jaAV might, Avhile in a rudimentary state, by some false or unnatural attach- ment of the dental sac, be so altered in its position as to pass up, in its groAvth, between the nose and orbit. But that the croAvn, after having been thus turned round in the socket, should remain stationary, Avhile the root passed doAvn and appeared outside of the gum, is a most extra- ordinary and remarkable anomalism. In the former instance, the tooth might still continue to derive the nutriment necessary for its vitality from the dental vessels; but in the latter case, it could not be so nourished Avithout difficulty, because the apex of the root, the place where the vessels and nerves enter, was entirely outside of the gum. The following is one of the several cases of deviation in the growth of the teeth, that have come under the author's observation : In 1840, he Avas requested to extract a tooth for a lady of Baltimore, under the following circumstances. She had, for a time, experienced a great deal of pain in her upper jaw, and supposed it to originate from the second molar of the right side, but which was perfectly sound. Meamvhile her general health became impaired, and her attending physician, thinking that the local irritation might have contributed to her debility, advised the extraction of the tooth. On removing it, the cause of the pain at once became apparent. The dens sapientise, which had not hitherto appeared, Avas discovered Avith its roots extending back to the utmost verge of the angle of the jaw, while its grinding surface had been in contact Avith the posterior surface of the crown and neck of the tooth just extracted. On the removal of the wisdom tooth, the pain ceased. About the middle of December, 1849, a youth aged sixteen applied to the author to extract a right superior bicuspid, which, he said, Avas ulcerated at the root. On examining his mouth, he discovered only one bicuspid, but above and betAveen the root of this and that of the 422 IRREGULARITY OF THE TEETH. first molar, he observed a small fistulous opening. On introducing a small probe, it immediately came in contact with the crown of a tooth looking toward the malar process of the superior maxillary, which, on extraction, proved to be the second bicuspid. The author has in his possession several molar and bicuspid teeth which have small nodes upon their necks, covered with enamel; and there is a jaw in the museum of the Baltimore Dental College which has five teeth presenting this anomaly. The author has two teeth in his possession of most singular shape, presented to him by his brother, the late Dr. John Harris. They were extracted in July, 1822, from the right side of the upper jaw of a young gentleman, nineteen years of age, by the name of Crawford. They occupied the place of the first and second bicuspids, and their crowns are almost wholly imbedded in lamellated dentine, that should have constituted their roots, but which are entirely wanting. Judging from their appearance, one would be inclined to suppose that their sacs failing to contract, they remained stationary in their sockets, and as the base of the pulps elongated, they came in contact with the bot- tom of the alveoli, and Avere caused to bulge out and to be reflected upon their crowns, to the enamel of which, nearly to their grinding surfaces, they are perfectly united. For some time previously to the extraction of these teeth, they had been productive of considerable irritation and pain in the gums and jaw, and it was for the relief of the suffering Avhich their presence induced that they were removed. Since the publication of the second edition of this Avork, the author has seen a still more remarkable deviation in the growth of a tooth. It is in the upper jaw of an adult skull in the Museum of the Baltimore Dental College. The natural teeth are all well formed, and regularly arranged in the alveolar border, but between the extremities of the roots of the superior central incisors, in the substance of the jaw, there is a supernumerary tooth, the crown of which looks upward toAA'ard the crest of the nasal plates of the two bones. The whole tooth is about one inch in length, and the apex of the crown is nearly on a level with the floor of the nasal cavities. There is also in the museum of this institution a central incisor of the upper jaw, with the root bent upon, and in contact with, the labial surface of the croAvn. Osseous Union of the Teeth. —- Inclosed as each tooth is in a distinct sac, and separated on either side by a bony partition, from the adjoin- ing teeth, until after the completion of the formation of the enamel, it is difficult to conceive how osseous union could take place betAveen two of these organs, and, we confess, that until we actually witnessed an example of it, which we did for the first time in 1836, Ave were inclined *.o doubt the possibility of such an occurrence. IRREGULARITY OF THE TEETH. 423 During a visit to the city of Richmond, Va., in April of the above mentioned year, we had an opportunity of seeing tAvo cases. One con- sisted in the union of the crowns of the central incisors of the upper jhav, the palatine surface of which presented the appearance of one broad tooth, while anteriorly they had the semblance of two teeth ; the other case consisted in the union of the right central and lateral incisors of the lower jaw. A professional friend in Virginia informed the author, in a conversa- tion some years since, that he had met with a case of osseous union between a second bicuspid and first molar of the lower jaw, which was so palpable that there could have been no doubt of its existence. Mr. Fox has given the drawings of four cases, the originals of Avhich, as Mr. Bell tells us, are still to be seen in the museum of Guy's Hospi- tal. Mr. B. also informs us that he has seen four other examples. Dr. Koecker is skeptical Avith regard to the existence of osseous union of the teeth, and attributes to those Avho assert that they have met Avith cases of it, " a weak credulity, a love of the marvellous, or a desire to impose upon the world." Cases of this sort, it is true, are of rare occurrence, and a connec- tion of the roots of two teeth, by an intervening portion of the alve- olus, is very easily mistaken for osseous union of the roots themselves. A few years since, in extracting a second molar of the upper jaw, the author brought the dens sapientise along with it. At first he thought there was osseous union of the roots, but upon close examination found a very thin portion of the alveolar Avail between, to Avhich their roots Avere firmly attached. Such a case as this would, in many instances, be set doAvn as an example of osseous union. It is easy to account for a lusus naturae of this kind, by supposing a previous union of the pulp of the two teeth. But from the order in Avhich the eruption of the teeth is effected, some classes appearing long before others, it Avould, on this supposition, seem that it could only occur betAveen the central incisors. It is not, however, thus lim- ited : the central and lateral incisors, the bicuspids, and the molars are sometimes united. An osseous union of the teeth is, fortunately, of rare occurrence; if it were otherwise, it Avould be productive of many accidents in the ex- traction of teeth. Apart from this consideration, it can be of but little importance either to the practitioner or to the physiologist. Since the publication of the first edition of this Avork, a number of cases of osseous union of the teeth have fallen under the observation of the author, and there are now many specimens in the anatomical collection of the Baltimore College of Dental Surgery. Among them are a number of examples of osseous union of the temporary teeth. 424 IRREGULARITY OF THE TEETH. Supernumerary Teeth. — The development of supernumerary teeth is usually confined to the anterior part of the mouth, and more frequently to the upper than to the lower jaw. They sometimes, however, appear as far back as the dentes sapientise, and Hudson says he has seen them behind these teeth. We have now in our anatomical collection, two supernumerary teeth that were extracted, one from behind and the other at the side of one of the upper wisdom teeth.* The crowns of supernumerary teeth which appear in the anterior part of the mouth are usually of a conical shape, and for the most part situated between the central incisors; they usually have short, knotty roots; sometimes, however, they bear so strong a resemblance to the other teeth that it is difficult to distinguish the one from the other. We once saw two lateral incisors in the lower jaw, both of which were so Avell arranged, and perfectly formed, that it was impossible to de- termine which of the two ought to be considered as the supernumerary. Mr. Bell mentions a case in which there were five lower incisors, all of which were well formed and regularly arranged. The author has met with several examples in which supernumerary teeth in the lower jaw so closely resembled the natural incisors that no difference could be discerned between them. He has also seen examples of three lateral incisors in the upper jaw where it was impossible to determine which was the supernumerary. Supernumerary cuspids rarely if ever occur, but supernumerary bicuspids are occasionally met with. Delabarre says he has seen them; and Ave have met Avith three examples of the sort; in each of these instances the teeth were very small, not being more than one-fourth as large as the natural bicuspids, with oval crowns, and placed partly on the outside of the circle, and partly between the bicuspids. We ex- tracted one of them, and have it still in our possession. Its root is short, round, and nearly as thick at its extremity as it is at the neck of the tooth. The supernumerary teeth that appear further back than the bicus- pids, though much smaller, bear a strong resemblance to the dentes sapientise. Supernumerary teeth, although generally imperfect in their forma- tion, are less liable than other teeth to decay. This may be attribut- able to the fact that they are harder, and, consequently, not so sus- ceptible to the action of the causes that produce the disease. Although the occurrence of supernumerary teeth rarely disturbs the arrangement of the others, their presence is sometimes productive of the worst kind of irregularity; and even when they do not have this * These teeth were removed by Dr. Chewning, dentist, of Fredericksburg, Va, IRREGULARITY OF THE TEETH. 425 effect, they impair the beauty of the mouth, and, for this reason, should be extracted as soon as their crowns have completely emerged from the gums. To the practitioner of dental surgery, the occurrence of supernu- merary teeth is interesting, only in so far as it affects the beauty of the mouth and the relationship which the teeth of the upper jaAV sustain to those of the lower; but to the physiologist it involves the question, Avhat determines their development? In propounding this interrogatory, however, it is not our intention to enter upon its dis- cussion in this place, as it forms no part of the design of the present treatise. Third Dentition.— That nature sometimes makes an effort to produce a third set of teeth is a fact which, hoAvever much it may be disputed, is now so Avell established, that no room is left for cavil or doubt. The following interesting particulars are taken from " Good's Study of Medicine:" " We sometimes, though rarely, meet with playful attempts on the part of nature to reproduce teeth at a very late period of life, and after the permanent teeth have been lost by accident or by natural decay. ' "This most commonly takes place between the sixty-third and eighty-first year, or the interval Avhich fills up the two grand climac- teric years of the Greek physiologist; at which period the constitution appears occasionally to make an effort to repair other defects than lost teeth. . . . " For the most part, the teeth, in this case, shoot forth irregularly, feAV in number, and without proper roots, and, even Avhere roots are produced, Avithout a renewal of sockets. Hence, they are often loose, and frequently more injurious than useful, by interfering with the uniform line of indurated and callous gums, Avhich, for many years perhaps, had been employed as a substitute for the teeth. A case of this kind is related by Dr. Bisset, of Knayton, in Avhich the patient, a female in her ninety-eighth year, cut twelve molar teeth, mostly in the loAver jaAV, four of which Avere thrown out soon afterward, while the rest, at the time of examination, were found more or less loose.. "In one instance, though not in more than one, Mr. Hunter wit- nessed the reproduction of a complete set in both jaws apparently Avith a reneAval of their sockets. 'From which circumstance,' says he, 'and another that sometimes happens to women of this age, it would appear that there is some effort in nature to renew the body at that time.' " The author of this work once attended a lady in the country, Avho cut several straggling teeth at the age of seventy-four; and, at the same time recovered such an acuteness of vision, as to throw away her 426 IRREGULARITY OF THE TEETH. spectacles, Avhich she had made use of for more than twenty years, and to be able to read with ease the smallest print of the newspapers. In another case, that occurred to him, a lady of seventy-six, mother to the late Henry Hughes Eryn, printer of the journals of the House of Commons, cut two molars, and at the same time completely recovered her hearing, after having for some years been so deaf as to be obliged to feel the clapper of a small hand-bell, Avhich was always kept by her, in order to determine whether it rung or not. "The German Ephemerides contain numerous examples of the same kind; in some of which teeth were produced at the advanced age of nine- ty, a hundred, and even a hundred and twenty years. One of the most singular instances on record is that given by Dr. Slade, which occurred to his father, Avho, at the age of seventy-five, reproduced an incisor, lost twenty-five years before, so that, at eighty, he had hereby a perfect row of teeth in both jaAvs. At eighty-two, they all dropped out suc- cessively ; two years afterward, they Avere all successively renewed, so that at eighty-five he had once more an entire set. His hair, at the same time, changed from a white to a dark hue; and his constitution seemed, in some degree, more healthy and vigorous. He died suddenly at the age of ninety or a hundred. " Sometimes these teeth are produced with wonderful rapidity; but in such cases with very great pain, from the callosity of the gums through which they have to force themselves. The Edinburgh Medical Com- mentaries supply us Avith an instance of this kind. The individual Avas in his sixty-first year, and altogether toothless. At this time, his gums and jaw-bones became painful, and the pain was at length excruciating. But within the space of twenty-one days from its commencement, both jaAvs were furnished with a new set of teeth, complete in number." A late physician of Baltimore informed the author, in 1838, that an example of third dentition had come under his OAvn observation. The subject, a female, at the age of sixty, he assured him, erupted an entire set in each jaw. The folioAving extract of a letter from a professional friend,* de- scribes another very interesting case : "I have just seen a case of third dentition. The subject of this 'playful freak of nature,' as Dr. Good styles it, is a gentleman residing in the neighborhood of Coleman's Mill, Caroline County, Virginia. He is now in his seventy-eighth year, and, as he playfully remarked, 'is just cutting his teeth.' There are eleven out, five in the upper and six in the lower jaw. Those in the upper jaw are tAvo central incisors, one lateral and two bicuspids, on the right side. Those in the lower are the four incisors, one cuspid and one molar. Their appearance is that * Dr. J. D. xMcCabe. IRREGULARITY OF THE TEETH. 427 of bone, extremely rough, Avithout any coating or enamel, and of a dingy brown color." Two cases somewhat like the foregoing have come under the author's observation. The subject of the first was a shoemaker, Mr. M., of Baltimore, who erupted a lateral incisor and cuspid at the age of thirty. Two years before this time, he had been badly salivated, and, in consequence, lost four upper incisors and one cuspid. The alveoli of these teeth exfoliated, and, at the time he first saw him, Avere entirely detached from the jaw, and barely retained in the mouth by their adhesion to the gums. On removing them, he found two Avhite bony protuberances, which, on examination, proved to be the crowns of an incisor and cuspid. They were perfectly formed, and though much shorter than the other teeth, yet up to 1845, they remained quite firm in the jaw. The subject of the other case was a lady, residing near Fredericks- burg, Virginia, who erupted four right central incisors of the upper jaAV successively. One of her temporary teeth, in the first instance, had been permitted to remain too long in the mouth, and a permanent central incisor, in consequence, came out in front of the dental arch. To remedy this deformity, the deciduous incisor Avas, after some delay, removed ; and, about tAvo years after, the permanent tooth, not having fallen back into its proper place, Avas also extracted. Another two years having elapsed, another tooth came out in the same place and in the same manner, and, for similar reasons, was also removed. To the astonishment of the lady and her friends, a fourth incisor made its appearance in the same place two years and a half after the extrac- tion of the first permanent tooth. When it had been out about eigh- teen months, the author Avas called in by the lady, who wished him, if possible, to adjust it. Finding that it could not be brought within the dental circle, he advised her to have it extracted, and an artificial tooth placed in the proper place in the arch. In the second number of the eighth volume of the American Jour- nal of Dental Science, the history of a case of four successive denti- tions of the upper central incisors is given.* It is said that the efforts made by nature for the production of a third complete set of teeth are so great that they exhaust the remain- ing energies of the system, and, as a consequence, that occurrences of this kind are generally soon followed by death. The author is not aware that any attempt has ever been made to explain the manner of the origin and formation of the teeth of third dentition. The rudiments of the teeth of first and second dentition * Dr. W. H. Dwinelle. 428 IRREGULARITY OF THE TEETH. originate from mucous membrane, Avhile those of third dentition would seem to> be the product of periosteal tissue or bone. In obedience to what laAV of developmental anatomy are the teeth of third dentition formed? Certainly not to any one primitively impressed upon the animal economy, as they have never been known to appear Avhile the teeth of second dentition remain in the jaws. If the establishment of the laAV which governs the development of a part depends upon a certain condition of other contiguous parts, it is possi- ble that the following may be a correct explanation of the phenomenon of third dentition. Certain parts, in certain states or conditions, and in particular locations, perform functions peculiar to themselves. In other Avords, the condition and location of a part determines the func- tion or functions it performs. For example, Avhen the mucous mem- brane along the course of the alveolar border begins to assume a dupli- cated or grooved condition, which it does at about the sixth week of. intra-uterine existence, dental papillse shoot up from it; and when, by a similar duplication of this same tissue, behind the sacs of the tem- porary teeth, forming what Mr. Goodsir styles " cavities of reserve," the papillse of the permanent teeth, one from the bottom or distal extremity of each duplication, begin to be developed. Hence, it Avould seem that this particular state or condition of this tissue, and in these particular locations, is necessary to determine the development of teeth germs. This arrangement or condition of mucous membrane, in these particular locations, Avhich always results from the develop- ment of the foetus, may be sometimes produced by accidental causes, after all the organs of the body have attained their full size, or at any time during life; and Avhen it does occur, it is not unreasonable to suppose that a neAv tooth papilla should be formed. Proceeding still farther, the development of a dental papilla is the signal for the pro- duction of a dental follicle, Avhich ultimately becomes a sac, and then an organ to supply the tooth now considerably advanced in the process of formation, with a covering of enamel. But as the maxillary bone has previously attained its full size, it rarely, if ever, happens that alveoli are formed for these accidental productions, and, consequently, they seldom have roots, or if they do, they are very short and blunt. They are usually connected with the periosteum of the alveolar bor- der, and this union is sometimes so close and intimate that very con- siderable force is necessary for their removal, or, at least, so far as our own observations go upon the subject, and we have had occasion to extract several in the course of our practice. As a general rule, how- ever, they become loose in the course of a few years and drop out. But it may be asked, how are such accidental duplications of the mucous membrane formed ? This is a question, we admit, which it IRREGULARITY OF THE TEETH. 429 may not be easy to answer satisfactorily; but we do not think it at all improbable that they sometimes occur during the curative process that follows the removal of one or more teeth. The granulated Avails of the gums surrounding an alveolus from which a tooth has been ex- tracted, may become covered with this tissue before the socket is filled with a deposit of new bone, or it may cover the surfaces of the dupli- cated membrane near the bone; and Avhenever such arrangement or condition of this tissue takes place upon the alveolar border, (and that it may, occasionally, we think there can be no question,) it is probable that a new tooth papilla is produced, which, in the progress of its devel- opment, induces the formation of the various appendages necessary to the production of a perfect tooth. This, in the opinion of the author, is the only way that these fortu- itous productions can be accounted for in accordance with true physio- logical principles. It seems impossible to explain the manner of their formation in any other way. All must admit that the presence of mucous membrane is necessary, and Ave cannot conceive of any other Avay by which its presence beneath the general surface of the gums can be accounted for; but if Ave admit this explanation to be correct, the question is at once solved. We believe it is also owing to the accidental occurrence of a certain arrangement or condition of the mucous membrane concerned in the production of the permanent teeth, consisting, most likely, in the formation of "cavities of reserve" more than are called for by the teeth of this dentition, that the de- velopment of supernumerary teeth takes place. The operations of nature, it is true, are so secretly carried on, that we cannot see the precise modus operandi by which they are effected; yet in the development of the various organs and structures of the body, we may see them at the various stages of their growth, and note what precedes their arrival at these various stages in the progress of their formation, and upon which their accretion would seem to be dependent. The periods for the arrival of these stages of develop- ment, though somewhat irregular, occur for the most part in normal conditions of the body, at certain fixed epochs. Thus, the papilla of the first temporary molar may usually be seen between the sixth and seventh weeks of intra-uterine existence, but previously to this time a slight groove or depression is observable in the mucous membrane of the part from whence it has its origin. The same is true with regard to the papillae of all the other teeth, though the time for the commencement of their formation occurs at later periods. The pecu- liar change Avhich takes place in the arrangement of the mucous tissue here, as Avell as the periods at Avhich they occur, are doubtless de- termined by certain stages in the development of other parts, and 430 IRREGULARITY OF THE TEETH. these, very likely, may determine the established number of teeth in both dentitions. If the foregoing views which we have advanced be correct, these fortuitous productions are not the result of a mere freak of nature, as they are sometimes facetiously styled. They are the result of the operation of an established law of the economy, and although, after the completion of the teeth of second dentition, its course is suspended, the occurrence of a similar arrangement or condition of the mucous tissue in the parts in question will again put it in operation. Method of Directing Second Dentition.—There is nothing more de- structive to the beauty, health, and durability of the teeth, and no disturbance more easily prevented, than irregularity of their arrange- ment. Also, in proportion to the deviation of these organs from their proper position in the alveolar arch, are the features of the face and the expression of the countenance injured. It also increases the sus- ceptibility of the gums and alveolo-dental membrane to morbid im- pressions. It is important, therefore, that the mouth, during second dentition, should be properly cared for; and so thoroughly convinced is the author of this, that he does not hesitate to say, that if timely pre- cautions were used, there would not be one decayed tooth where there are now a dozen. Much harm, it is true, may be done by improper meddling with the teeth during this period, but this, so far from inducing a total neglect, should only make those having the care of children more solicitous in securing the services of scientific, accomplished practitioners. For the judicious management of second dentition, much judgment and a correct knowledge of the normal periods of the eruption of the several classes of teeth are required. All unnecessary interference with these organs, at this early period of life, should certainly be avoided, as it Avill only tend to mar the perfection at Avhich nature ever aims. The legitimate duty of the physician being, as Mr. Bell correctly observes, "the regulation of the natural functions when deranged," he should never anticipate the removal by nature of the temporary teeth, unless their extraction, is called for by some pressing emergency, such as a deviation of the permanent ones from their proper place, alveolar abscess, or exfoliation of the alveolar processes. The mouth should be frequently examined from the time the shed- ding of the deciduous teeth commences until the completion of second dentition; and when the growth of the permanent teeth so far outstrips the destruction of the roots of the temporary, that the former are caused to take an improper direction, such of the latter as have occa- sioned the obstruction should be immediately removed. In the denti- IRREGULARITY OF THE TEETH. 431 tion of the upper front teeth, this should never be neglected; for, Avhen they come out behind the temporaries, as they most frequently do, and are permitted to advance so far as to fall on the inside of the lower incisors, a permanent obstacle is offered to their subsequent proper adjustment. When a wrong direction has been given to- the growth of the loAver front teeth, they are rarely prevented from acquiring their proper ar- rangement by an obstruction of this sort. They should not, hoAvever, on this account be permitted to occupy an erroneous position too long; for the evil will be found easier of correction Avhile recent than after it has continued for a considerable length of time. The irregularity should be immediately removed. The permanent central incisors of the upper jaw being larger than the temporaries of the same class, it might, therefore, be supposed that the aperture formed by the removal of the one would not be sufficient for the admission of the other, without an increase in the size of this part of the maxillary arch. It should be recollected, however, that by the time these teeth usually emerge from the gums, the crowns of the temporary lateral incisors are so much loosened by the partial destruction of their roots, as to yield sufficiently to the pressure of the former, to permit them to take their proper position Avithin the dental circle. When this does not happen, the temporary laterals should be extracted. Under similar circumstances, the same course should be pursued Avith the permanent lateral incisors and the temporary cuspids, and also Avith the permanent cuspids and the first bicuspids. But from the fact that the bicuspids are erupted before the perma- nent cuspidati, the premature extraction of the temporary cuspidati is often the cause of the projection of one or more of the front teeth ; some- times to such a degree as to produce considerable deformity. The removal of the temporary cuspidati should therefore be avoided Avhen there is reason to believe that the growth of the jaw will provide sufficient space for a deviating permanent lateral incisor to take a proper position Avithin the dental arch. The bicuspids being situated between the roots of the temporary molars are seldom caused to take an improper direction in their groAvth. Nor are they often prevented from coming out in their proper place for want of room. In the management of second dentition much Avill depend on the experience and judgment of the practitioner. If he be properly informed upon the subject, and gives to it the necessary care and atten- tion, the mouth will, in most instances, be furnished with a healthful, well arranged, and beautiful set of teeth. At this time, "an opportu- 432 IRREGULARITY OF THE TEETH. nity," says Mr. Fox, " presents itself for effecting this desirable object," (the'prevention of irregularity,) "but everything depends upon a cor- rect knowledge of the time when a tooth requires to be extracted, and also of the particular tooth, for often more injury is occasioned by the removal of a tooth too early than if it be left a little too long ; because a new tooth, which has too much room long before it is required, will sometimes take a direction more difficult to alter than a slight irregu- larity occasioned by an obstruction of short duration." Mr. Bell objects to the extraction of the temporary teeth, especially in the loAver jaw, to make room for the permanent, on the ground that the practice is harsh and unnatural — that it often gives rise to a con- traction of the maxillary arch. This objection, if it Avas well founded, should deter every dentist from adopting the practice; except as a dernier ressort, as the lesser of two evils. But when the temporary teeth, by remaining too long, are likely to affect the arrangement, and consequently, the health of the perma- nent teeth, they should be extracted; because, in that case, their pres- ence is a greater evil than any that would be occasioned by their removal. As a general rule, they should be suffered to remain until their presence is likely to injure the permanent teeth and their contigu- ous parts. When the permanent teeth are crowded, the lateral pressure is fre- quently so great as to fracture the enamel. If this cannot be prevented in any other way, one on each side should be extracted. It is better to sacrifice two than permanently to endanger the health of the whole. The file should never be used with a view to remedy irregularity; the extraction of tAvo teeth, one on each side of the jaw, however small the space required to be gained may be, is far preferable. The second bicuspids, cozteris paribus, should always be removed rather than the first, but sometimes, the extraction of the first becomes necessary. By the removal of the teeth, ample room will be gained for the arrangement of all the remaining ones, and the injury resulting from a crowded condition of the organs prevented. The author does not, however, wish to be understood as conveying the idea that filing the teeth necessarily causes them to decay, for, Avhen the file is used for any other purpose than to gain room, the apertures may be made large enough to prevent the approximation of the organs, and thus the bad effects resulting from the operation will be prevented. The extraction of the root of a superior front tooth, a central incisor, for example, when the crown has been greatly disfigured or Avholly de- stroyed by mechanical violence, occasions a contraction of the arch which may cause the superior front teeth to fall behind the inferior teeth. Should the contraction, however, occur without such a deform- IRREGULARITY OF THE TEETH. 433 ity resulting, it frequently happens that an unsightly space is left, too small for the insertion of an artificial tooth to correspond in size with the adjoining natural ones. To avoid such results, the root should be allowed to remain, and the proper treatment instituted to subdue the inflammation, the pulp re- moved when exposed, and the root filled to the apex with gold or other suitable material. By pursuing such a course, the root is retained until such a time as its removal will not affect the adjoining teeth. In some cases the portion of the crown destroyed may be restored with gold, or an artificial crown inserted on a pivot. On filing teeth, to prevent irregularity, Dr. Fitch judiciously re- marks : " I consider the expediency of filing or not filing the teeth ought to be a subject of serious deliberation on the part of the dental practitioner, never, especially in young persons, performing the opera- tion, unless obliged to do so, to cure actual disease. I Avas greatly surprised, therefore, in the late work of Mr. Bell, to see directions to file slightly irregular and crooked teeth so as to gain the room of about half a tooth. Nature, when permitted to proceed Avith her work without interrup- tion, is able to perform her operations in a perfect and harmonious manner. But the functional operations of all the parts of the body are liable to be disturbed from an almost innumerable number and variety of causes, and impairment of one organ often gives rise to derangement of the whole organism. For the relief of which the interposition of art not unfrequently becomes necessary, and it is fortunate for the well- being of man that it can in so many instances be applied with success. In sound and healthy constitutions, the services of the dentist are seldom required to assist or direct second dentition. In remarking upon this subject, Dr. Koecker observes, "that the children, for whom the assistance of the dentist is most frequently sought, are those who are in a delicate, or at least in imperfect, constitutional health; in whom the state not only of the temporary teeth, but of the permanent also, is to be considered; and, where both are found diseased, the future health and regularity of the latter require the greatest consider- ation of the surgeon. " Irregularity of the teeth is one of their chief predisposing causes of disease, and never fails, even in the most healthy constitutions, to destroy, sooner or later, the strongest and best set of teeth, unless pro- perly attended to. It is thus not only a most powerful cause of destruc- tion to the health and beauty of the teeth, but also to the regularity and pleasing symmetry of the features of the face; always producing, though slowly and gradually, some irregularity, and not unfrequently the most surprising and disgusting appearance." 28 434 IRREGULARITY OF THE TEETH. Though nature is generally able to accomplish the task assigned her, yet there are times when she requires aid, and it is then, and then only, that the services of the dentist are needed. Therefore, whilst, on the one hand, we should guard against any uncalled for interference, we should, on the other, always be ready to give such assistance as the nature of the disturbance presented to our notice may require. Irregularity of Arrangement of the Teeth. — The temporary teeth seldom deviate from their proper place in the alveolar arch; but irreg- ularity of arrangement is of frequent occurrence in the permanent teeth, especially the cuspids and incisors. The first and second molars are seldom irregular; for, like the teeth of first dentition, they rarely encounter obstruction in their growth and eruption. The first molars being the first of the permanent set to appear, the ten anterior teeth are limited to that part of the arch occupied by the ten milk teeth: if this space is too small, irregularity must of necessity ensue. The dentes sapientise are sometimes irregularly erupted in conse- quence of a want of correspondence between the development of the tooth and the growth of the maxilla. The tooth in such cases takes usually the direction of least resistance, the croAvn presenting more or less obliquely forward, backward, outward, or inward. Of these four positions, the first and fourth are found usually in the lower jaw; the second and third are most common in the upper jaw. When a bicuspid is forced from its proper place, it turns inward to- ward the tongue, or outward toward the cheek, accordingly as it is in the upper or lower jaw. The cuspids, AA'hen prevented from coming out in their proper place, make their appearance either before or be- hind the other teeth. When they come out anteriorly, which they do more frequently than posteriorly, they often become a source of annoy- ance to the upper lip, excoriating and sometimes ulcerating the mucous membrane. The incisors of the upper jaw present a greater variety of abnormal arrangement than any of the other teeth. The centrals come out sometimes before and sometimes behind the arch ; at other times, their median sides are turned either directly or obliquely forward toward the lip. The laterals sometimes appear half an inch behind the arch, looking toward the roof of the mouth; at other times, they come out in front of the arch, and at other times, again, they are turned obliquely or transversely across it. When any of the upper incisors are very much inclined toward the interior of the mouth, the loAver teeth, at each occlusion of the jaws, shut before them, and become an obstacle to their adjustment. This is a difficult kind of irregularity to remedy, and often interferes with the lateral motion of the jaw. IRREGULARITY OF THE TEETH. 435 The lower incisors sometimes shut in this manner even when there is no inward deviation of the upper teeth. In this case the irregularity is OAving to preternatural elongation of the lower jaAV, Avhich arises more frequentty from some fault of dentition than from any congenital defect in the jaw itself. Sometimes t]ie superior maxillary arch is so much contracted, and the front teeth in consequence so prominent, that the upper lip is pre- vented from covering them. Cases of this kind, hoAvever, are rarely met Avith ; but when they do occur, it occasions much deformity of the face, and forms a species of irregularity very difficult to correct. From the same cause the lateral incisors are sometimes forced from the arch, and appear behind the centrals and cuspids, the dental circle being filled with the other teeth. There are many other deviations in the arrangement of the incisors. Mr. Fox mentions one that was caused by the presence of two super- numerary teeth of a conical form, situated partly behind and partly betAveen the central incisors, which, in consequence, Avere thrown for- Avard, while the laterals Avere placed in a line Avith the supernumeraries. The central incisors, though half an inch apart, formed one toav, and the laterals and supernumeraries another. Mr. Fox says he has seen three cases of this kind. This description of irregularity is rarely met Avith. M. Delabarre says that cases of a transposition of the germs of the teeth occasionally occur, so that a lateral incisor takes the place of a central, and a central the place of the lateral. A similar transposition of a cuspid and lateral incisor is, also, sometimes seen. Two cases of this sort have fallen under the observation of the author. The incisors of the lower jaw being smaller than those of the upper, and in other respects less conspicuous, do not so plainly sIioav an irreg- ularity in their arrangement, nor is the appearance of an individual so much affected by it. Still it should be guarded against; for such deviation, Avhether in the upper or lower jaAV, may prove injurious to the health of the teeth and to the beauty of the mouth. The growth of the inferior permanent incisors is sometimes more rapid than the destruction of the roots of the corresponding temporaries. In this case the former emerge from the gums behind the latter, and some- times so far back as greatly to annoy the tongue and interfere Avith enunciation. At other times the permanent centrals are prevented from assuming their proper place, because the space left for them by the temporaries is not sufficient. The irregularity in the former of these two cases is greater than in the latter. The same causes, in like manner, affect the laterals. M. Delabarre mentions a defect in the natural conformation of the 436 IRREGULARITY OF THE TEETH. jaAvs, by which the upper temporary incisors on one side of the median line are thrown on the outside of the loAver teeth, while the corres- ponding teeth, on the other side of the same line, fall Avithin. The same arrangement, he says, may be expected, unless previously reme- died, in the permanent teeth. The author has met Avith but two cases of this sort, and the subjects of these he did not see until after they had reached maturity. Treatment of Irregularity. — Orthodontia, or the treatment of irreg- ularity, should accord with the indications of nature. When the irregularity is neither great nor complicated, and its causes are re- moved before the nineteenth or twentieth year, the teeth, without the aid of art, will, in most cases, assume their proper position. When, hoAvever, the efforts of the economy are unavailing, recourse should be had to the dentist, who can, in most instances, bring the deviating organs to their proper position in the arch. Teeth incline to return to their place on the removal of the cause of irregularity. They may be also made to change position under the influence of pressure. The pressure must be constant; it must be sufficient to cause motion, yet not so great as to set up destructive inflammation ; lastly, it must be continued until the teeth can be kept in place by antagonism with the opposing teeth; or in case there is no such antagonism, the regulating appliance must be worn more or less constantly for a year, or even longer. The regulating appliance should be as simple in its construc- tion as is possible to accomplish the purpose, so that both time and labor may be saved, and the patient be able to attend to its removal and adjustment when it becomes necessary to cleanse it; this should frequently be done. Teeth artificially regulated change position chiefly, if not entirely, by the double process of absorption from one side of the socket, fol- lowed by the slower process of ossific deposit on the opposite side. It- is therefore essential to success that the tooth be retained in its new position, either by the other teeth or by mechanical appliance, until such deposit is formed. Many cases fail from a want of persistence on the part of patient or dentist. How far, and in Avhat direction a tooth may be moved, will depend partly upon the position of the apex of the root; partly upon the antagonism of the opposing teeth. Cuspids growing out far up on the alveolar arch will usually be found to have short and curved roots. The attempt to move them might cause the curved apex to pierce the alveolus. Even Avhen not curved, the root is short, and the regulated tooth will not possess that durability which is characteristic of the cuspids. It should ahvays be borne in mind that in regulating teeth the crown is the movable IRREGULARITY OF THE TEETH. 437 point, whilst the apex of the root is the fixed point, and must deter- mine in great degree the extent and direction of motion Again, the natural or artificial movement of bicuspids backward to make room for front teeth may be aided or hindered by the opposing teeth. An upper bicuspid, for instance, once carried back, so that the posterior slope of the lower bicuspid strikes it, will retain its position or may be thrown even farther back. Upper incisors striking inside the lower, or lower incisors unnatu- rally prominent, may be regulated, and the opposing teeth will tend to keep them in their corrected position. But it will require long and patient use of the regulating apparatus to keep in place upper incisors which project outward, or lower incisors inclining inward. In deciding upon the removal or extraction of an irregular tooth, it should not be forgotten that a tooth moved by mechanical appliance, especially if the change in position is considerable, will not prove as durable as if no movement had been necessary. Hence it may some- times be advisable to extract irregular cuspids in cases Avhere their correction requires much change in their position and that of the bicuspids. In a case very recently presented to Prof. Austen, the superior arch was perfectly regular and closely filled ; but both cuspids had come out above the arch. The cuspid roots Avere normal, and it seemed practicable to bring these teeth doAvn into the places of the first bi- cuspids. But the four bicuspids were sound, and the first bicuspids gave very much the appearance of the natural arrangement. Hence, as in point of expression, there would be no great gain, and in point of durability, a probable loss, it was not thought advisable to subject the patient to the tedious annoyance of regulation. The practicability of altering the position of a tooth, after the com- pletion of its groAvth, was Avell known to many of the early practi- tioners. But before the commencement of the present century, the principal object of the dentist was the insertion of artificial teeth; orthodontia, therefore, met with little attention. Fauchard and Bourdet were among the first to study this branch of dentistry. They invented a variety of fixtures for adjusting irregular teeth ; but most of these were so aAvkward in their construction, and occasioned so much incon- venience to the patient, that they were seldom employed. Mr. Fox was among the first to give explicit directions for remedy- ing irregularity of the teeth, and his method of treatment has formed the basis of the established practice for more than fifty years. This long trial has proved it to be founded upon correct physiological prim ciples and much practical experience. In describing the treatment of irregularity, we shall notice the 438 IRREGULARITY OF THE TEETH. means by which some of its principal varieties may be remedied; otherwise, the application of the principles of treatment Avould not be well understood, since it must be varied to suit each individual case. As a general rule, the sooner irregularity in the arrangement of the teeth is remedied the better; for the longer a tooth is allowed to occupy a wrong position, the more difficult will be its adjustment. The position of a tooth may sometimes be altered after the eighteenth, twentieth, or even the thirtieth year; but it is better not to delay the application of the proper means until so late a period. A change of this kind may be much more easily effected before the several parts of the osseous system have reached their full development, and Avhile the formative process is in vigorous operation, than at a later period of life. The age of the subject, therefore, should ahvays govern the practitioner in forming an opinion as to the practicability of cor- recting irregularity. Previously to the tAventieth year, the Avorst varie- ties of irregularity may, in most cases, be successfully treated. The first thing claiming attention in the treatment is the removal of its causes. Whenever, therefore, the presence of any of the tem- porary teeth has given a false direction to one or more of the perma- nent, they should be extracted, and the deviating teeth pressed several times a day with the finger, in the direction they are to be moved. This, if the irregularity has been occasioned by the presence of a deciduous tooth, Avill, generally, be all that is required. But when it is the result of narrowness of the jaAV, either natural or acquired, a permanent tooth on either side should be removed, to make room for such as are improperly situated. All the teeth being sound and well formed, the second bicuspids are the teeth which should be extracted; but if, as is often the case, the first permanent molars are so much decayed as to render their preservation impracticable, or, at least, doubtful, these teeth should be removed in their stead. After the removal of the second bicuspids, the first, usually, very soon fall back into the places which they occupied, and furnish ample room for the cuspids and incisors. But if they fail to do this, they may be gradually forced back by inserting wedges of wood or rubber between them and the cuspids, or by means of a ligature of silk, or gum elastic, securely fastened to the first molar on each side. These should be re- newed every day, until the desired result is produced. The most frequent kind of irregularity, resulting from narroAvness of the jaw, is the prominence of the cuspids. These teeth, Avith the exception of the second and third molars, are the last of the teeth of second dentition to be erupted ; consequently they are more liable to be forced out of the arch than any others, especially Avhen it is so much contracted as to be almost entirely filled before they make their IRREGULARITY OF THE TEETH. 439 appearance. The common practice in such cases was to remove the projecting teeth. But as the cuspids contribute more than any of the other teeth, except the incisors, to the beauty of the mouth, and can, in almost every case, be brought to their proper place, the practice is injudicious. Instead of removing these, a bicuspid should be extracted from each side. When the space between the lateral incisor and the bicuspid is equal to one-half the width of the crown of the cuspid, the second bicuspid should be removed, but Avhen it is less, the first should be taken out; because, although the croAvn of the latter may be carried far enough back after the removal of the former to admit the croAvn of the cuspid betAveen it and the lateral incisor, the root of this tooth will remain in front and partly across the root of the first bicuspid; leaving a more or less prominent vertical ridge on the anterior part of the alveolar border, which, to some extent at least, acts as an irritant to the gums and periosteum. As the incisors of the upper jaAV are more conspicuous than those of the loAver, and when well arranged contribute more to the beauty of the mouth, their preservation and regularity are of greater relative importance. Hence, the removal of a lateral incisor, Avhen it is situ- ated behind the dental arch, as is often done Avith a view to remedy the deformity produced by false position, is a practice Avhich cannot be too strongly deprecated, provided sufficient space can be made for it between the cuspid and central incisor, by the removal of a bicuspid from each side of the jaw. In describing the treatment of irregularity, we shall commence with an incisor occupying an oblique or transverse position across the alveolar ridge; so that the cutting edge of the tooth, instead of being in a line with the arch, forms an angle Avith it of from forty to ninety degrees. This variety of deviation is rarely met with in both centrals, but often occurs with one. Some dentists have recommended in cases of this sort, Avhen the space betAveen the adjoining central and lateral incisor is equal to the Avidth of the deviating tooth, to turn the latter in its socket Avith a pair of forceps, or to extract and immediately re- place it in its proper position. It is scarcely necessary to say that if a tooth is extracted or turned in its socket, the vessels and nerves from Avhich it derives nourishment and vitality are severed; hence, though its connection Avith the alveolus may be partially re-established, it Avill be liable to act as a morbid irritant, and be subject to inflammation from comparatively slight causes. The tooth, hoAvever, may be brought to its proper position, Avithout incurring the risk of injury, by accurately fitting a gold ring or band, with knobs on the labial and palatine sides; to each of these a ligature should be attached. Thus fastened to the ring, each end should be 410 IRREGULARITY OF THE TEETH. carried back, one on either side, in front and behind the arch, and secured to the bicuspids as represented in Fig. 168, so as to act con- stantly upon the irregular tooth. The ligatures should be reneAved from day to day, until the tooth assumes its proper position. Should the space not be sufficient to permit the use of the band, the method Fig. 168. Fig. 169. practised by Mr. Tomes, as shown in Fig. 169, will be found very effective. A plate is fitted to the inside of the arch, and a band car- ried in front and soldered to projections .from the plate, which pass between the bicuspids. On each side of the irregular tooth a metallic dovetail is fastened, and pieces of compressed wood inserted into them. The SAvelling of the wood gradually turns the tooth. In a few days the metal sockets will require to be changed in position, and in a few weeks the tooth may be thus brought nearly or quite to its natural place. If the space permits, these two methods may be advantageously com- bined. Use the plate as in Fig. 169 with the inner dovetail ; but for the long outside band substitute the band (Fig. 168) around the tooth, with a loop on the median side ; from this pass an elastic liga- ture to a hook soldered on the plate. The tooth is turned on its axis by the combined pull of the ligature and thrust of the wood. Before attempting to turn the deviating organ, it should be ascer- tained if the aperture between the adjoining teeth is sufficient to admit of the operation. If not, it should be increased by the extraction of a bicuspid from each side of the jaw, and moving the teeth in front of them backward until sufficient room is obtained. The time required to do this Avill vary from three to eight or ten weeks, depending upon the number of teeth to be acted on, and the age of the patient. A sufficient space may sometimes be gained by pressing outward the adjoining teeth in cases where they fall within the normal curve of the arch. This may be done by the expansion of wood or rubber, con- tained in metal sockets attached to the plate, behind each tooth to be moved. IRREGULARITY OF THE TEETH. 441 Narrowness of the alveolar border is a frequent cause of irregularity of the incisors. In this case, the centrals usually project, though it sometimes happens that some are in front and some behind the arch, producing great deformity. To remedy Avhich, the second bicuspids should be removed, unless the first molars are so much affected by caries as to render their preservation doubtful. In this case, they should be extracted, in place of the second bicuspids. If bicuspids and first molars are sound, and the decision turns upon the probable relative durability of the teeth, statistics decide very positively in favor of the bicuspids, especially under the age of fifteen. But the position of the first molar is too far back to permit, in all cases, the full benefit of the space gained by its extraction. The following case will serve to illus- trate the means employed for remedying this description of deformity. The sub- ject was a young lady fifteen years of age. Her teeth presented the arrange- ment as seen in Fig. 170. The second molars of the upper jaAV occupied their proper position in the alveolar arch, or, in other Avords, they were a little more than an inch and a quarter apart; the first molars Avere hardly an inch apart, and the first bicuspids AA'ere still nearer to each other. The cuspids, except that they were pushed a little too far fonvard, occupied, very nearly, their proper position. The right central and left lateral incisors pro- jected fully a quarter of an inch, lifting and otherwise annoying and disfiguring the upper lip; the left central was thrown behind and partly between the right central and left lateral, while the right lateral occupied a position in a line with it. Without going into a minute detail of the method adopted for pre- paring the appliance used, it will be suffi- cient to refer the reader to Fig. 171. This represents a plaster model of the teeth, alveolar border, palatine arch, and the ap- paratus for remedying the deformity. The second bicuspids were first extracted, then, by means of ligatures applied to the sec- ond molars and first bicuspids, and made fast to a band of gold passing on the out- side of the arch, Avhich were reneAved every day, these teeth were brought out to their proper position in eleven weeks ; this done, Fig. 170. 442 IRREGULARITY OF THE TEETH. there was a space of nearly an eighth of an inch betAveen the cuspids and first bicuspids; this Avas filled up by bringing back the cuspids Avith ligatures. A ligature Avas next applied to the right lateral, passed through a hole in the gold band in front, and made fast. In ten days this tooth was brought to its proper place. A ligature was now attached to a knob soldered on the gold plate which had been fitted to the inside of the teeth and palatine arch for this purpose, and tied tightly in front of the projecting right central incisor. In about three Aveeks this was brought to a position alongside the lateral incisor of the same side. The left central Avas then, in like manner, brought forward, and the left lateral carried backAvard to its proper place. After the deformity was corrected, the teeth presented the arrange- ment represented in Fig. 172, taken from a plaster model made from an impression of the regulated teeth. To correct the irregularity in this case, it re- quired, in all, twenty-one weeks. If all the teeth could have been acted upon at the same time, the operation might have been accomplished in a shorter period. It was found necessary, too, in consequence of the diseased action of the gums, occasioned by the apparatus, to remove it every eight or ten days, and let it remain off each time twenty-four hours. It may be proper also to observe that every time the ligatures were removed, it was taken from the mouth, and the teeth thoroughly cleansed. For moving a projecting incisor or cuspid backward, a gold spiral spring was formerly employed. It was found to be more efficient than a ligature of silk, inasmuch as it kept up a constant traction upon the deviating tooth. But it is objectionable on account of the annoyance it causes the patient. A ligature of rubber is far preferable, and this material is noAV very generally employed in the treatment of every description of irregularity in which agencies of this sort are required. The difficulty of tying India-rubber ligatures is obviated by the use of several sizes of delicate elastic tubing (French manufacture), from which sections may be cut, more or less thick, according to the required length and power of the ligature. Each strip becomes thus an endless band which may be readily passed from one tooth to another or to a hook on the plate. There are other kinds of irregularity of the upper incisors; but we shall only notice one, which, from its peculiar character, is sometimes exceedingly difficult to remedy. It is when one or more of these teeth IRREGULARITY OF THE TEETH. 443 are placed so far back in the jaAV that the under teeth come before it or them at each occlusion of the mouth. Of this kind, Mr. Fox enumerates four varieties: The first is, Avhen one of the central incisors is situated so far back that the lower teeth shut over it, while the other central remains in its proper place, as represented in Fig. 173, which is copied from his work, as are also those Avhich follow. Fig. 173. Fig. 174. The second is, when both of the centrals have come out behind the circle of the other teeth, and the laterals occupy their oAvn proper position, as represented in Fig. 174. The third is, when the lateral incisors are thrown so far back that the under teeth shut before them, Avhile the centrals are well arranged, as exhibited in Fig. 175. Fig. 175. Fig. 176. The fourth is, Avhen all the incisors are placed so far behind the arch that the lower teeth shut before them, as in Fig. 176. He might also have added to these a fifth variety; for it sometimes happens that the cuspids of the upper jaw are thrown so far back as to fall on the inside of the loAver teeth. The author has met with several such cases. Two things are necessary in the treatment of the kind of irregularity just described : first, to prevent the upper and lower teeth from coming entirely together, by placing betAveen them some hard substance, so that the overlapping incisors may not interfere with the necessary out- ward movement. The second is, the application of some fixture that will exert a constant and steady pressure upon the deviating teeth, until they pass those of the lower jaAV. 444 IRREGULARITY OF THE TEETH. For the accomplishment of this, various plans have been proposed. Duval recommended the application of a grooved or guttered plate, and Catalan invented an instrument, based, we believe, upon the same principle, but much better adapted to the purpose. We doubted the utility of the inclined plane of Catalan until we had employed it, and found it an effectual and speedy method of moving deviating front teeth in the upper jaw from behind the dental circle to their proper places. It acts Avith great force, and in the proper manner for the ac- complishment of the object. But this very force, and the difficulty of controlling it, make it necessary to be careful in its use, especially upon partially erupted teeth. The roots of such teeth are in process of formation, and of course highly vitalized, and are very susceptible to injury from the shock of repeatedly striking upon the inclined plane. In the application of this principle for the correction of irregularity, the author has been in the habit of constructing the apparatus some- what differently. With a metallic die and counter-dies, he has a plate of gold struck up over all the teeth, Avhen practicable, as far back as the first or second molar, completely encasing them and the alveolar Fig. 177. Fig. 178. IRREGULARITY OF THE TEETH. 445 resentation of an inclined plane for bringing forward a central incisor Avhich had come out about a quarter of an inch behind the circle of the other teeth. The manner of the action of this instrument upon the deviating tooth is shoAvn in Fig. 178. The plan proposed by Delabarre, as shown in Fig. 179, taken from his treatise on second dentition, is to pass silk ligatures (a) around the teeth, in such a way that a properly directed and steady pressure will be exerted on such of the teeth as are situated behind the arch. To keep the jaws from coming in contact, he recommends the application of a metallic grate (b) fitted to two of the inferior molars. A cap of vulcanized rubber is preferable to the metallic grate. This plan possesses the merit of simplicity, and occasions little or no inconvenience to the patient. It will, however, sometimes be found not only inefficient, but also injurious in its action upon the teeth adjacent to those to be brought forward. The force on the irregular teeth, and those against which the ligatures act, being equal, and in opposite directions, the latter will be drawn back, while the former are brought forward; thus the means used for the correction of one evil will some- times occasion another. The author has tried it, hoAvever, in some cases Avith the most satisfactory results. Mr. Fox recommended a gold bar about the sixteenth part of an inch in width, and of proportionate thickness, bent to suit the curvature of the mouth, and fastened with liga- tures to the temporary molars of each side. It is pierced opposite each ir- regular tooth Avith two holes. The teeth of the upper and lower jaw are prevented from coming entirely to- gether by means of thin blocks of ivory, attached to each end of the bar by small pieces of gold, and resting upon the grinding surfaces of the temporary molars. (Fig. 180.) After the instrument has been thus fastened to the teeth, silk liga- tures are passed round such as are within the arch, and through the holes opposite them, and then tied in a firm knot on the outside of the bar. The ligatures must be reneAved every three or four days, until the teeth shall have come fonvard far enough to strike in front of those that formerly shut before them, and until they shall have acquired a sufficient degree of firmness to prevent them from returning to their former position. As soon as the teeth shut perpendicularly upon each other, the blocks may be removed, and the bar alone retained. Since 1830, many practitioners, both in England and the United 416 IRREGULARITY OF THE TEETH. States, have substituted caps of gold, or, Avhat is better, of vulcanized rubber, for the blocks of ivory recommended by Mr. Fox, and in- stead of simply bending the bar, they noAV swage it betAveen metallic casts, so that all its parts, except those immediately opposite the irreg- ular teeth, may be perfectly adapted to the dental circle. The appa- ratus, with these modifications, is more comfortable, and less liable to move upon the teeth. Mr. Fox directs that the blocks of ivory be placed upon the tem- porary molars ; but the caps of gold or rubber noAV substituted are entirely disconnected from the bar, and are often used after the moult- ing of these teeth ; they are then placed upon the first permanent molars. As the caps prevent the teeth from coming together, masti- cation, during the time they are Avorn, is, necessarily, performed on them. They should, therefore, be placed upon the largest and strongest teeth; and for this reason they should be applied to the molars. The curved bar should be washed, and the teeth cleansed every time the ligatures are reneAved. If this be neglected, the particles of food that collect between it and the teeth will soon become putrid and offen- sive, constituting a source of disease both to the gums and teeth. Be- fore the bar is applied, it should be ascertained Avhether there is suffi- cient space for the deviating teeth, and if there is not, room should be made in the manner before described. Some diversity of opinion exists as to the most suitable age for the correction of this description of irregularity. Mr. Fox, it Avould seem, preferred the period immediately previous to the shedding of the tem- porary molars — probably the tenth or eleventh year after birth. Others think that the anterior part of the dental arch continues to ex- pand until the second denture is completed, and that the bicuspids afford a better support for the ends of the bar than any other teeth, and are content to Avait until the fifteenth or even sixteenth year. But, though the arch does sometimes expand a little, yet even when the expansion occurs, it is generally so inconsiderable, that little advantage can be derived from it. Moreover, the arch, instead of expanding, is much more liable to contract whenever a vacancy occurs in the dental circle, either by the extraction, or from the improper groAVth of one or more of the teeth ; hence, the difficulty is apt to be increased by delay. The evil, it is true, may be remedied at the fifteenth, seventeenth, or even eighteenth year; but it is rarely advisable to defer it to so late a period. The most that is required in the treatment of irregularity of the lower incisors is to remove a tooth, and to apply frequent pressure to the deviating organs. The loAver incisors are less conspicuous than those of the upper jaw, and the loss of one, if the others are well arranged, is scarcely perceptible. IRREGULARITY OF THE TEETH. 447 The use of vulcanite or hardened India-rubber promises to be of great value in the correction of irregularities. The peculiar manipula- tions it requires will be found in another portion of this work; it is only necessary, therefore, in concluding this chapter, to briefly mention the properties Avhich fit it for this important branch of dental practice. It admits of absolutely perfect adaptation to the teeth. If only a part of the crowns of the teeth require fitting, a wax impression will be suffi- ciently accurate. But if the gum and undercut surfaces of the teeth are to be fitted, a plaster impression is necessary. Prof. Austen's method of taking plaster impressions in gutta-percha cups AArill enable a skilful operator to take an accurate impression of any mouth, how- ever irregularly the teeth may be arranged. A closely fitting vulcanite plate can be worn with comfort; hence the patient is not tempted to remove it. It has no motion ; hence does not wear the teeth or irritate the gums. Its firmness of adaptation makes it an excellent " fixed point," from which to make pressure or traction in any required direction upon the irregular teeth: the coun- ter pressure, being distributed over all the regular teeth, is not felt. When it is necessary to cap the molars, a layer of varying thickness should be carried over them all, to prevent the soreness caused by mas- tication upon any one tooth. Any variety of appliance may be used in connection Avith the plate, that the judgment of the operator suggests, as best adapted to bring about the required change. The plastic nature of the crude material permits enlargement or extension in any direction, without the neces- sity of soldering, as in metallic plates, and with an exactness which cannot be had in carving ivory blocks. Thus, prominences may be left behind teeth which are to be moved outward ; in Avhich may be made dovetails for the insertion of com- pressed Avood ; slits or holes for India-rubber, Avhich makes more rapid pressure than the Avood ; or holes for the insertion of small screAvs. These screws may bear directly against the tooth, and be turned slightly each day or tAvo. Or the portion of the plate next the tooth or teeth to be moved may be separated with a delicate saw from the plate ; the ends of the screw or screws playing into this move the tooth or teeth by a broad bearing, which will, in certain cases, be better than the point of the screAV. Or a small piece of vulcanized rubber may be taken ; one end fitting against a molar or bicuspid, and into the other end a screAV thread cut to receive a delicate screAV ; on the head of this screAV a second piece of rubber may be fitted against the tooth, to be moved so as to allow the screAV to be turned without changing its position on the tooth. This combination forms a miniature jack-screw, similar to those recom- 448 IRREGULARITY OF THE TEETH. mended some years since by Dr. Dwindle, and will often be found use- ful. It may be used in combination with the rubber plate by attaching one end to the plate instead of resting it against a tooth. If it is desired to move a tooth by the elasticity of a spring, this can be made of vulcanite; one end of it fitting tightly into a groove cut in the plate, so that the free end shall bear with the requisite force against the tooth. The elastic slip or spring can readily be bent by means of a Avarm burnisher, so as to press with greater or less force, as the case may demand. Fig. 181, taken from Mr. Tomes' work, will illustrate one variety of the application of springs; in this case pressing outward and later- ally the left central and right lateral incisors. This mode of making press- ure will be found very useful. It acts steadily, is under control, and does not need renewal so often as the Avedges of wood or rubber. Where ligatures are required, the vulcanite plate affords an easy means of attaching them in any desired posi- tion ; passing them through holes and tying; looping them over projecting knobs of vulcanite, or over small metal hooks set in the plate; or stretching them through slits sawn in the plate. If a band is to be carried for any purpose in front of the arch, it may be connected with the plate on the inside 'of the arch, through any spaces occurring between the bicuspids or molars ; if there are no such spaces, or if they are to be closed up in the process of regulation, the cap which is often required to pass over the molars will connect the tAvo. But the outside band is not often necessary. The inside plate is less aAvkward to the patient; it is out of sight; and almost, if not quite, every required movement can be obtained from it, even to the exclusion of the inclined plane of Catalan. The case described on page 439, Fig. 170, could have been advan- tageously treated by the use of a vulcanite plate; the various stages progressing nearly at the same time. The impression in this case to be taken in plaster; the plate capping the second molars ; first molars and first bicuspids carried outward by wooden or elastic wedges, or by a double spring of vulcanite fastened to the plate opposite each space of the extracted second bicuspids ; the left central and right lateral car- ried out by Avedges or screAvs ; the right central and left lateral brought in by ligatures looped over hooks in the plate. At the completion of IRREGULARITY OF THE TEETH. 449 the Avork a neAv impression to be taken, and the plate worn until the teetn" become firmly set, passing a ligature around the tAvo outstanding teeth, to prevent their tendency to return to their old positions; the plate itself would keep the others in place. A text-book can only give general principles and illustrate them by a feAV examples; for the varieties of irregularity are almost endless. Their successful treatment demands a correct knoAvledge of physiologi- cal and pathological action to know when and where to act; a skilful hand and an inventive wit to know just what to do and how to do it. In conclusion, to sum up briefly, do not interfere where by simple extraction the case will correct itself: when teeth must be moved, do it decidedly, to avoid tedious delay ; but take care not to be so rapid as to excite inflammation : do not move teeth Avith deformed or defec- tive roots; do not sacrifice sound and regular bicuspids to bring into the arch teeth which will require to be moved through a great space, for this movement materially impairs their durability; lastly, do not attempt to bring teeth to a position where you cannot keep them until firm ossific deposit makes them permanent in their new positions. Where the superior central incisors project beyond the inferior so much as to give a pointed appearance to the lip, Dr. Kingsley recom- mends the following regulating appliance: A rubber plate fitting the roof of the mouth is constructed on a plaster model, taken from a plas- ter impression, in the same manner as any other vulcanized rubber plate Avould be made. This plate, Avhich is made as delicate as strength and durability Avill permit, is cut away opposite the irregular incisors, so that there may be room for these to be pressed in. The pressure, which is brought to bear in such a manner as not only to move these incisors, but to act more or less upon the whole arch, is made by means of a very simple contrivance, such as a piece of gold, formed in the shape of a T, about a quarter of an inch in length, and with a staple or ring at the bottom of the upright portion of the T, through which a ligature may be passed. This ligature is a rubber ring, cut from a piece of small rubber tubing, and is passed through the eyelet in the T and then attached to the plate, reaching directly to the second molars on either side. The plate being introduced into the mouth, the T is brought forward and passed between the central incisors, so that the cross-bar of the T is brought to bear upon their labial surfaces. If the incisors are in close contact, space is made for the gold bar forming the part of the T which projects into the mouth, by wedging. The effect of this appli- ance will be to draw the central incisors inward, and at the same time to force the side teeth outAvard. To prevent the incisors from return- ing to their abnormal position, delicate rubber rings may be used,, being 2«J 450 IRREGULARITY OF THE TEETH. Fig. 182. slipped over the incisors and attached to a close-fitting retaining plate of rubber covering the roof of the mouth. An appliance for correcting irregularity, invented by Dr. Redman, consists of a vulcanized rubber plate fitting the roof of the mouth, and covering the exterior surfaces of the teeth which give it support. This plate is cut aAvay in the direction in which any tooth is to be moved, and Avedges of Avood inserted in holes made in the plate, bear- ing upon the deviating teeth, either from the outside or inside, as the case may require. The wedges of Avood are changed from time to time as the moving of the teeth may require. The appliance is easily removed by the patient for the purpose of cleansing it. Deformity from Excessive Development of the Teeth and Alveolar Ridge of Lower Jaw. — When the teeth of the loAver jaAV form a larger arch than those of the upper, the incisors and cuspids of the former shut in front of those of the latter, causing the chin to project, and otherwise impairing the symmetry of the face. Figs. 182 and 183 present a front and a side view of this deformity. It may result from a want of correspondence in the devel- opment of the teeth and alveoli of the two maxilla, the upper jaw being defec- tive in size, while the lower jaw is natural ; or the former being natu- ral, the latter may be in excess. It may also arise from a simple eversion of the lower teeth or inversion of the upper. Treatment. — The remedial indications of the deformity in question consist in dimin- ishing the size of the dental arch, Avhich is always a te- dious and difficult operation, requiring great patience and perseverance on the part of the patient, and much me- chanical ingenuity and skill on the part of the dentist. The appliances to be em- ployed have, of necessity, to be more or less complicated, requiring the most perfect accuracy of adaptation and neatness of execution; they must also be worn for a long time, and, as a natural consequence, are a source of considerable annoyance. The first thing to be done Fig. 183. IRREGULARITY OF THE TEETH. 451 is to extract the first inferior bicuspids. Sufficient room will thus be obtained for the contraction which it will be necessary to effect in the dental arch for the accomplishment of the object. An accurate im- pression of the teeth and alveolar ridge should be taken with wax, softened in warm water, and from this impression a plaster model is procured, and afterward a metallic die and counter-die, in the manner to be described in a subsequent chapter. This done, a gold plate of the ordinary thickness should be swaged to fit the first and second molars, (if the second has made its appear- ance, and if not, the second bicus- pid and first molar on each side,) so as completely to encase these teeth. If these caps are not thick enough to prevent the front teeth from coming together, a piece of gold plate may be soldered on that part of each which coArers the grinding surfaces of the teeth. Having proceeded thus far, a small gold knob is soldered to the inner and outer front corners of both caps, and to each of these a ligature of silk or rubber is attached. These ligatures are to be brought forward and tied tightly around the cuspids. When thus adjusted, the lower arch will present the appearance exhibited in Fig. 184. By this means the cuspids may, in fifteen or tAventy days, be taken back to the bicuspids. If in their progress they are not carried toward the inner part of the alveo- lar ridge, the outer ligatures may be left off after a few days, and the inner ones alone employed to complete the remainder of the operation. After the positions of the cuspids have been thus changed, a circular bar of gold should be made, extending from one cap to the other, so as to pass about a quarter of an inch behind the incisors, and be sol- dered to the inner side of each cap. A hole is to be made through this band behind each of the incisors, through which a ligature of silk may be passed and brought forward and tied tightly in front of each tooth. These ligatures should be reneAved every day until the teeth are carried far enough back to strike on the inside of the correspond- ing teeth in the upper jaAV. Fig. 185 represents the appearance which the loAver jaw presents with the last-named apparatus upon it, and will better convey an idea of its construction, the manner of its application, and its mode of action, than any description Avhich can be gi\Ten. An appliance of this sort may be made to act with great efficiency Fir.. 184. 452 IRREGULARITY OF THE TEETH. in remedying the deformity in question; but, in its application, it is necessary that the caps be fitted with the greatest accuracy to the teeth, and they should be re: moved every day and thoroughly cleansed, as well as the teeth they cover. If this precaution is neg- lected, the secretions of the mouth, which collect between the gold caps and teeth, will soon become acid, and corrode the latter. The remarks made in the pre- vious chapter upon the use of the vulcanite are applicable here. Such a plate, for this class of cases, is readily made, and inflicts no injury upon teeth or gums-. Elastic, instead of silk, ligatures might be used, and the retraction of the incisors carried on simultaneously Avith that of the cuspids. The use of vulcanized rubber instead of gold is of great value in correcting irregularities of this nature, the form of the appliances being the same. Protrusion of the Lower Jaw.—This deformity, although produced by a different cause from the one last described, is similar to it, and gives to the lower part of the face an unnatural and sometimes disa- greeable appearance. It also interferes with mastication, and often with prehension and distinct utterance. It wholly changes the rela- tionship which the teeth should sustain to each other when the mouth is closed. The cusps or protuberances of the bicuspids and molars of one jaAV, instead of fitting into the depressions of the corresponding teeth of the other, often strike their most prominent points; at other times, the outer protuberances of the lower molars and bicuspids, instead of fitting into the depressions of the same class of teeth in the upper jaw, shut on the outside of these teeth. The trituration of aliments i& consequently rendered more or less imperfect. This protrusion of the lower jaw is supposed by some to be the result of a "natural partial luxation." In fact, its causes are by no means clearly understood. It is often hereditary, and would seem to be caused by that mysterious agency which impresses peculiarities of groAVth and shape not only upon the lower maxilla, but upon every bone in the body. This agency is so constant and over-ruling, that we must be prepared to find the jaw returning to its position after the discontinu- ance of treatment; unless, by the interlocking of the cusps of the upper teeth and the overlapping of the upper incisors, we can restrain the tendency. It is of more frequent occurrence than the one which results from excessive development of the teeth and alveolar ridge, and requires, IRREGULARITY OF THE TEETH. 453 as before stated, an entirely different plan of treatment It rarely occurs previously to second dentition. Treatment.—The plan of treatment usually adopted consists in fast- ening on each side a small block of ivory or a cap of vulcanite on one of the'lower molars, thick enough to keep the front teeth about a quarter of an inch apart Avhen the jaAA's are closed. Fox's bandage must now be applied. This is buckled as tightly as the patient can bear Avith convenience, pressing the chin upward and backward. A piece of tough Avood, slightly hollowed so as to fit the arch of theloAver teeth, made narrow at the upper end, is introduced between the teeth several times a day, the concave portion resting upon the duced, they would be of a different and less aggravated character. Any disposition or vice of body Avhich Aveakens the vital energies of the system, increases the susceptibility, or rather excitability, of all its parts — those of this cavity equally Avith the rest. There are various kinds which have this effect; as, for example, the scorbutic, scrofulous, ven- ereal, mercurial, &c, each of which may influence the character of the morbid action in a manner peculiar to itself; or it may be similar to that which might be exercised by another, only causing it to assume a greater or less degree of malignancy, accordingly as the functional operations of the body generally are more or less enervated by it. This seems to be the way in Avhich a bad habit of body is capable of affecting the maxillary sinus. It is a predisposing, but not an exciting cause of disease; and it is important that this distinction should be borne in mind. The one should never be confounded with the other, because an error of this sort might, in many instances, lead to the adop- tion of incorrect vieAVs concerning the therapeutical indications of the disease. This part of the subject we shall have occasion to advert to hereafter. Inflammation and ulceration of the nasal pituitary membrane some- times extend themselves to the maxillary sinus; but disease is not so frequently propagated from the nasal fossae to this cavity as the inti- mate relationship between the two might lead one to suppose. It is seldom that both are affected at the same time. Hence we infer, that, although lined by one common membrane, the propagation of disease from one to the other is a rare occurrence. The obliteration of the nasal opening of this cavity is sometimes caused by disease in the nose, and is followed by mucous engorgement of the sinus, inflammation of the lining membrane, distention of the DISEASES OF THE MAXILLARY SINUS. 465 osseous Avails, and not unfrequently by other and more complicated forms of disease. But the closing of this opening is oftener an effect than a cause of disease in this cavity, and it generally re-establishes itself without any assistance of art after the cure of the affection Avhich caused it. If all the circumstances connected with the history of the diseases under consideration could be ascertained, Ave think it Avould be found that these affections are more frequently induced by a morbid condi- tion of the teeth, gums, and alveolar processes than any other cause. There are, in fact, no sources of irritation to which this cavity is so much and so often exposed as those arising from the dental organism. It is separated from the apices of the roots of the superior molars and bicuspids by only a very thin plate of bone, and is sometimes even penetrated by them ; so that it could scarcely be otherwise than that aggravated and protracted disease in the teeth and alveoli should exert an unhealthy influence upon it. The pain occasioned by diseased teeth is often very severe, sometimes almost excruciating, and inflam- mation in the alveoli-dental periosteum and gums frequently extends itself to the whole of one side of the face. It could hardly be possi- ble, therefore, for this cavity to escape. Alveolar abscess, and some- times necrosis and exfoliation of the socket of the affected tooth, arise from the inflammation thus lighted up. It often happens that the gums and alveolar periosteum are affected for years with chronic inflammation and other morbid affections. If, in addition to these facts, other proofs be necessary to establish the agency of dental and alveolar irritation in the production of dis- ease in the maxillary sinus, they may be found. Many of the affec- tions here met with are often cured by the removal of diseased teeth after other remedies have been employed in vain, and that Avithout eAren perforating the antrum. This would not be the case if the irri- tation did not arise as a consequence of the dental malady. Most writers on diseases of the sinus agree in ascribing them to a morbid condition of the teeth and alveoli. There are some, however, who, though they admit that dental irritation may, perhaps, occasion- ally give rise to them, seem, nevertheless, to attribute their occurrence, in the majority of instances, to other causes, such as irregular exposure to cold, blows upon the face, and certain constitutional diseases. We shall iioav proceed to the consideration of some of the more common affections of this cavity, under their respective and appropriate heads. Inflammation of the Lining Membrane of the Maxillary Sinus. — Inflammation, Avhen not complicated Avith any other morbid affection, is the most simple form of disease to Avhich the pituitary membrane of the antrum is subject. As it precedes and accompanies all others, 30 466 DISEASES OF THE MAXILLARY SINUS. it will be proper to offer a few remarks upon it before entering upon the consideration of those of a more aggravated nature. Inaccessible as it is here to most of the acrid and irritating agents to Avhich it is exposed in the nasal fossae and some other cavities of the body, it would rarely become the seat of inflammation were it not for its proximity to the teeth and alveolar border; and simple inflamma- tion rarely gives rise to any other form of diseased action, unless favored by some general morbid tendency, but usually'subsides spon- taneously on the removal of the exciting cause. In good constitutions it is less subject to inflammation, and, consequently, to any other description of morbid action, than those in whom there exists some vice of body or constitutional predisposition. Febrile and gastric affections; eruptive diseases, such as measles, small-pox, etc.; syphilis, and excessive and protracted use of mercurial medicines; a scorbutic or scrofulous diathesis of the general system — in short, everything that has a tendency to enervate the vital powers of the body increases its irritability. When in a healthy condition, it secretes a slightly viscid, transpa- rent and inodorous fluid, by which it is constantly lubricated; but inflammation changes the character of the secretion. It causes it to become vitiated; at first less abundant, it is afterward secreted in larger quantities than usual, becomes more serous, and so acrid as sometimes to irritate the membrane of the nose, over Avhich it passes after having escaped from the antrum. It also exhales an odor more or less offensive, accordingly as the inflammation is mild or severe. It moreover gives rise to a thickening of the membrane, and sometimes to obliteration of the nasal opening. This last rarely occurs; but when it does happen, an accumulation of the secretion and other mor- bid phenomena, of which we shall hereafter treat, result as a necessary consequence. If at any time during the continuance of the inflammation, the pa- tient is attacked with severe constitutional disease, the local affection will be aggravated, and sometimes assume a different character. The inflammation, when long continued, degenerates into a chronic form, and is sometimes kept up for several years, Avithout giving rise to any other unpleasant symptoms than occasional paroxysms of dull and seemingly deep-seated pain in the face, and a vitiated condition of the fluids of this cavity. The slightly fetid odor which they exhale ceases to be annoying or even perceptible to the patient, when he be- comes accustomed to it. Symptoms. — The symptoms of inflammation here, though not always precisely the same as elsewhere, are, for the most part, very similar. They are severe, fixed, and deep-seated pain under the DISEASES OF THE MAXILLARY SINUS. 467 cheek, extending from the alveolar border to the lower part of the orbit; local heat, pulsation, and sometimes fever. Boyer says these symptoms are not ahvays present, and that inflammation may exist when it is not suspected. Other affections of the face and superior maxilla may be mistaken for this, and this for others; but that inflam- mation should exist, Avithout being attended Avith pain or any other signs indicative of its presence, is scarcely probable. Deschamps"distinguishes the symptoms of this from those of other affections of this cavity by a dull, heavy pain in the region of the sinus, Avhich, he snys, becomes sharp and lancinating, and extends from the alveolar arch to the frontal sinus. The disease goes on without interruption, increasing until the superior maxilla of the affected side is more or less involved. This malady, he says, cannot be confounded with any other, even Avhere there is no external visible cause; differing from a simple retention of mucus, by being painful at the commencement, and not by being accompanied with swelling of the bones ; from polypus, by the continuance of pain; and from cancer, by the character of the pain. "Suppuration and ulcers have peculiar signs AA'hieh cannot be confounded Avith those of inflammation." Pain in the molar and bicuspid teeth, accompanied by a sense of fluctuation in the parts, he seems to regard as a very certain indication of inflam- mation, and especially when joined to the other symptoms. "If an external cause is discovered, it Avill furnish a certain diagnosis:" he also mentions fever and headache as almost invariable accompani- ments. The inflammation, if not subdued by appropriate remedies, after having continued for a length of time, gradually assumes a chronic form; the pain then begins to diminish, and is less constant; it becomes duller, and is principally confined to the region of the antrum. The teeth of the affected side cease to ache, or ache only at times, but still remain sensitive to the touch. The mucous membrane of the nostril next the diseased sinus is often tender and slightly inflamed ; and if in the morning, or after tAvo or three hours' sleep, the other nostril be closed by pressing upon it with the thumb or one of the fingers, and a violent expiration be made, a thin watery fluid, of a slightly fetid odor, will be discharged, and pain will be experienced in the region of this cavity. Causes. —All morbid conditions of the teeth and gums, causing irri- tation in the alveolar periosteal tissue, may be regarded as among the most frequent of its exciting causes, especially caries, necrosis, and exostosis; also, loose teeth, and the roots of such as have been either frac- tured in an attempt at extraction, or by a bloAV or fall, and left in their sockets, or that have remained after the destruction of their crowns by 468 DISEASES OF THE MAXILLARY SIN decay. It sometimes happens, too, that inflammation is excited in this membrane by fractured alveoli; but when an accident of this sort occurs, the detached portions of bone are generally soon thrown off by the economy, and the cause being removed, the inflammation immediately subsides. Not so with the roots of the teeth. They often remain con- cealed in their sockets for years, unless removed by art. Nature, it is true, makes an effort to expel them from the jaw, but this is accom- plished only by a slow and very tedious process, and not, in many in- stances, until they have given rise to some serious affection. But of the deleterious effects that result from necrosed roots of teeth in the alveoli, it is not necessary now to speak; as extraneous bodies, they are always productive of more or less irritation. We might also men- tion exposure to sudden transitions of temperature, and certain con- stitutional diseases, as among the causes which occasionally give rise to inflammation of this membrane. Treatment. — The curative indications of inflammation of the lining membrane of the antrum are simple, and, for the most part, similar to those of inflammation in other parts of the body. In many cases, great benefit will be derived from the application of leeches to the cheek, as recommended by Mr. Thomas Bell. When the disease is dependent, as in most cases it is, upon an unhealthy condition of the alveolar processes, the first thing to be done is to remove all such teeth, or roots of teeth, as are productive of the least irritation ; for Avhile any local sources of irritation are permitted to remain, neither topical nor general bleeding, or indeed any other treatment, will be of perma- nent advantage. Simple inflammation of the lining membrane of the antrum would be of little consequence, Avere it not that it is liable to give rise to other and more dangerous forms of disease, such, for instance, as engorgement or a purulent condition of its secretions. It should never, therefore, be permitted to continue, but be as speedily arrested as possible; and for the accomplishment of this, the means here pointed out will, if timely and properly applied, be found fully adequate. Purulent Condition of the Secretions and Engorgement of the Maxillary Sinus.—A purulent condition of the secretions of the maxillary sinus and mucous engorgement are, indiscriminately, though very improperly, denominated by many writers on the affections of this cavity, abscess. To this, neither bears the slightest resemblance. Deschamps treats of the former under the name of suppuration, and the latter, dropsy. Of the first, he says, " If, by the time the inflammation has passed, the surrounding parts cease to be painful, Avhile the affection still continues to cause pain in the antrum, and the fever, though diminished, occurs at irregular intervals, and if the inflammation is folloAved by pulsating DISEASES OF THE MAXILLARY SINUS. 469 pain, we have reason to suppose that an abscess has formed in the sinus; and all doubt Avill be removed, if, on the patient's inclining his head i,o the opposite side, matter is discharged into the nostrils, or if some tubercles are formed near the outer angle of the eye, or alveolar border, which last happens more frequently; and, finally, if the purulent matter, not finding any opening through which to discharge itself, distends the sinus to such an extent as to form a tumor outwardly upon the cheek." In short, all the symptoms which he mentions as belonging to the disease are those accompanying the one under con- sideration. The matter, he says, is of a " putrid serous consistence." Bordenave has fallen into a similar error. He terms an altered state of these secretions suppuration of the membrane, and says that inflammation is not necessary to it. He seems to have confounded with abscess of the antrum those cases of alveolar abscess Avhere the matter, instead of discharging itself, as it ordinarily does, by an open- ing through the alveolus and gum into the mouth, passes into that cavity. Again he asserts that the disease (suppuration, as he calls it) may be independent of the surrounding parts; and although ordina- rily implicated with an altered condition of them, he affirms, it is sometimes the effect of disease primarily seated in the cavity. There is no doubt that a purulent condition of the fluids of this cavity is often complicated Avith ulceration of the lining membrane; but that the affection is different from abscess, its very nature and situation are sufficient to shoAV. "A reference to the structure of the antrum," says Mr. Bell, " Avould appear to be sufficient to point out the improbability, to say the least, of the occurrence of abscess in such a situation. That a mucous membrane covering, in a thin layer, the whole internal sur- face of such a cavity, should become the seat of all the consecutive steps of true abscess, is a statement bearing on the face of it an obvious absurdity*" Notwithstanding the seeming improbability of such an occurrence, — and it is certainly one that very rarely happens,— abscess does sometimes develop itself in this cavity ; but it is a different affection altogether from that usually treated of under that name. When complicated Avith ulceration of the mucous membrane — and it is probable that a purulent condition of its secretions, in most in- stances, is thus complicated — the affection is analogous to ozaena, and many of the older Avriters designate it by that name. Mr. Bell describes it, and very properly too, as being similar to gonorrhoea ; both diseases alike consist in an alteration of secretion ; in the one case of the pitui- tary membrane, and in the other of the mucous lining of the urethra; but in neither instance does it possess any of the characteristics of abscess, though the matter in both is purulent. It has been before stated that the obliteration of the nasal opening 470 DISEASES OF THE MAXILLARY SINUS. was more frequently an effect than a cause of disease in the maxillary sinus; it does, however, sometimes become closed from other causes than an unhealthy condition of this cavity; Avhen this happens, en- gorgement of the sinus is the inevitable consequence. The fluids thus accumulated are not always at first purulent, although they may sub- sequently become so: when the closing of the opening is the result of previous disease in the antrum, the secretions are more or less altered from the very first. Accumulation of any secretion within the antrum, whether of mucus or pus, is a source of irritation to the lining membrane, and the press- ure which it ultimately exerts upon the surrounding Avails causes a neAv form of diseased action, Avhich not unfrequently involves in disease all the bones of the face as Avell as those of the base of the cranium. When prevented from escaping through the nasal opening, the secre- tion eventually makes for itself a Avay of escape — sometimes through the cheek ; at other times beneath it, just aboAre the alveolar ridge ; or through the palatine arch or alveoli by the sides of the roots of one or more of the teeth ; and from a fistula thus established fetid matter will be almost constantly discharged. From openings of this sort the matter is sometimes discharged for years, while the disease in the antrum, very frequently, does not seem to undergo any apparent change. At other times the membrane ulcerates and the bony walls become carious. A purulent secretion from the mucous membrane of this cavity, inde- pendently of caries of the bone, or even of simple fistulous openings, is an exceedingly troublesome and unpleasant affection. The odor from the matter is often very annoying even to the patient, and Avhen the secretions are retained for some days in the sinus before they escape, the fetor is almost insufferable. In good constitutions, the secretions of the antrum are not so liable to become purulent, though they be confined for a long time in the cavity, and thus become more or less offensive. Inflammation of the lining membrane (the immediate or proximate cause) may exist for years without giving rise to it. It is only in scrofulous, scorbutic, or debilitated habits that they are liable to become thus altered. The difference in the effects produced upon them and the surrounding parts, by inflammation, is OAving to the difference in the state of the constitu- tional health of those affected with it. Where a puriform state of the secretions is complicated with ulcera- tion of the membrane, the matter will have mixed with it a greater or less quantity of flocculi, sometimes of so firm a consistence as to block up the nasal opening and prevent its exit. Mr. Thomas Bell says he has seen more than one case in Avhich a considerable accumulation had taken place in the antrum, accompanied by the usual indications of DISEASES OF THE MAXILLARY SINUS. 471 this affection, (muco-purulent engorgement of the sinus,) Avhen a sudden discharge of the contents into the nose took place, " in consequence of the pressure having overcome the resistance which had thus been offered to its escape." Cases of a very similar nature have fallen under our observation, the history of one of which will be given in the course of this chapter. The formation of these flocculi rarely ceases, except with the cure of the ulcers on the membrane. They give rise to considerable irritation, and their presence always constitutes an obstacle to the cure. They are usually easily removed by injections. The pituitary membrane of the antrum, when in a healthy state, secretes, as we have before stated, a transparent, slightly viscid and. inodorous fluid, poured out only in sufficient quantity to lubricate the cavity. But when inflammation is excited in the membrane, its secre- tions soon become more abundant, and are at first thinner, afterward thicker and more glutinous. Their color and consistence are not always the same. Instead of being transparent, they sometimes have a dirty, opaque appearance; at other times they assume a greenish, Avhitish, or yellowish color, and in some instances they bear a considerable resem- blance to pus, which, it has been conjectured, might be owing to sup- puration of some of the mucous follicles and a mixture of pus with its secretions. Mr. Thomas Bell, hoAvever, inclines to the opinion that it is attributable to an "alteration simply" of the secretions of the cavity. Their color and consistence are determined by—the degree of inflam- mation ; the length of time it has existed; the state of the health of the lining membrane, and that of the surrounding osseous walls; the egress which the matter has from the sinus; and the general habit of the body. Affections of this sort are more common to young subjects than to middle-aged or persons in advanced life. An eminent French Avriter says that of three individuals affected with dropsy (mucous engorge- ment), the oldest Avas not twenty years of age. Symptoms. — The diagnoses of the several affections of the antrum are so much alike, that it is often difficult to distinguish those that belong to one from those attendant upon another. The symptoms of mucous engorgement and purulent accumulation, however, are gener- ally such as will enable the practitioner to distinguish, Avith considerable certainty, these from other affections. They are ahvays preceded by inflammation of the lining membrane; a description of the symptoms of which, having already been given, need not be repeated. Omitting these, Ave at once proceed to mention those by which they are accom- panied. In speaking of the symptoms more particularly belonging to a puru- lent condition of the secretions of the antrum, Deschamps says the 472 DISEASES OF THE MAXILLARY SINUS. affection may be distinguished by dull, heavy pain extending along the alveolar border. Upon this symptom alone, little reliance can be placed, as it is always present in chronic inflammation. In addition to this, he mentions — the presence of decayed teeth ; soreness in those that are sound; and, on the patient's inclining his head to the side opposite to the one affected, the discharge of fetid matter from the nose. These are very conclusive indications of purulent effusions in this cavity. Bordenave, after enumerating the symptoms indicative of inflammation, mentions the following as belonging to the affection of which Ave are noAV speaking: dull and constant pain in the sinus, extending from the maxillary fossae to the orbit; a discharge of fetid matter from the nose, Avhen the patient inclines his head to the opposite side, or when the nose is blown from the nostril of the affected side. These symp- toms are mentioned by almost every Avriter upon the subject, as indica- tive of a purulent condition of the secretions of the maxillary sinus. The symptoms of engorgement differ materially from those Avhich denote simply a purulent condition of the mucous secretions. The pain, instead of being dull and heavy, as just described, becomes acute, and a distressing sense of fulness and Aveight is felt in the cheek, accom- panied by redness and tumefaction of the integument covering the antrum. The nasal opening having become closed, the fluids of the cavity gradually accumulate until they fill it; when, finding no egress, they press upon and distend the surrounding osseous walls, causing those parts which are the thinnest ultimately to give way. The effects are generally first observable anteriorly beneath the malar prominence, where a smooth, hard tumor presents itself, covered with the mucous membrane of the mouth. But this is not always the point Avhich first gives Avay; the sinus sometimes bursts into the orbit, at other times outwardly through the cheek, or through the palatine arch. The long- continued pressure thus exerted upon the bony walls often causes the breaking down or softening of their tissues. The tumor, Avhich is at first hard, becomes in a short time so soft as readily to yield to pressure. A distention, Deschamps says, may be distinguished from other diseases that affect the skin or subcutaneous tissues by the uniformity or regularity of the tumor, its firmness at the commencement, the slowness with which it progresses, and, above all, by the natural appearance of the skin, and the absence of pain Avhen pressure is made upon the tumor. Obliteration of the nasal opening, he says, may be suspected by the dryness of the nostril of the affected side, the mucous membrane of which becomes thickened and the cavity contracted, inflammation and sponginess of the gums, loosen- ing and, sometimes, in consequence of the destruction of their sockets, DISEASES OF THE MAXILLARY SINUS. 473 displacement of the teeth, may also be mentioned as occasional accom- paniments of engorgement. Causes.— Inflammation of the mucous membrane is the cause of a purulent condition of the secretions of the maxillary sinus, and this arises more frequently from alveolo-dental irritation than from any particular habit of body or constitutional disturbance. Engorgement results from the obliteration of the nasal opening, which, in the case of altered secretion, is usually caused by inflammation and thickening of the lining membrane. Treatment. — The curative indications of muco-purulent secretion and engorgement of the maxillary sinus are, firstly, if the nasal open- ing be closed, the evacuation of the retained matter; secondly, the re- moval of all local and exciting causes of irritation; thirdly, and lastly, the restoration of the lining membrane to its normal function. For the fulfilment of the first, an opening must be made into the antrum, and this should be effected in that part which Avill afford the most easy exit to the retained matter. Several Avays have been pro- posed for the accomplishment of this object; and before Ave proceed further, it may not be amiss to notice some of the various methods that have been adopted by different practitioners. With regard to the tooth most proper to be extracted authors differ. Cheselden preferred the first or second molar. Junker recommends the extraction of the first or second bicuspid, and if a fistula had formed, to enlarge it instead of perforating the floor of the antrum. But the second molar, being directly beneath the most dependent part of the cavity, is the most suitable tooth to be removed. If this be sound, the first or third molar or either of the bicuspids, if carious, may be extracted in its stead, and, in fact, no tooth beneath the antrum, in an unhealthy condition, should be permitted to remain. Heath recommends the extraction of the first molar on account of the depth of its socket, and because it is more liable to decay than any of the other teeth. An opening having been effected through the alveolus of a tooth into the antrum, it should be kept open until the health of the cavity is restored. For this purpose, sounds and bougies adapted to the pur- pose have been introduced. When the natural opening is closed, the first indication, as has been stated, is the evacuation of the matter; and for this purpose, a per- foration should be made into the sinus, and the most proper place for effecting this, it has been shown, is through the alveolar cavity ot the second molar. It may, hoAvever, be penetrated from that of either of the other molars or bicuspids. The perforation, after the extraction of the tooth, is made with a 474 DISEASES OF THE MAXILLARY SINUS. straight trocar, Avhich Avill be found more convenient than those usu< ally employed for the purpose. The point of the instrument, having been introduced into the alveolus through which it is intended to make the opening, should be pressed against the bottom of the cavity in the direction toward the centre of the antrum. A feAV rotary motions of the instrument will suffice to pierce the intervening plate of bone.* If the first opening be not sufficiently large, its dimensions may be increased to the necessary size by means of a spear-pointed instrument. The entrance is usually attended with a momentary severe pain, and the Avithdrawal of the instrument followed by a sudden gush of fetid mucus. In introducing the trocar, care should be taken to prevent a too sudden entrance of the instrument into the cavity. Without this precaution, it might be suddenly forced against the opposite wall. It is not always necessary to perforate the floor of the antrum after the extraction of the tooth; it occasionally happens, as has already been remarked, that some of the alveolar cavities communicate with it. An opening having thus been effected, it should be prevented from closing until a healthy action is established in the lining membrane, and for this purpose a bougie, or leaden or silver canula, may be in- serted into the opening and secured to one of the adjacent teeth. It should, however, be removed for the evacuation, of the secretions at least twice a day. The formation of an opening at the base or most dependent part of the sinus will, in those cases Avhere a fistula has been previously formed, be followed, in most instances, by its speedy restoration. Having proceeded thus far, the cure will be aided by the employment of such general remedies as may be indicated by the state of the general health ; and for the dispersion of the local inflammation, leeches to the gums and cheeks will be found serviceable. The antrum may, in the mean time, be injected with, at first, some mild or bland fluid, and afterward with gently stimulating liquids. Diluted port Avine, weak solutions of the sulphate of zinc and rose-Avater, copper and rose-water, or permanganate of potash, answer admirably, es- pecially the latter. Diluted tincture of myrrh may sometimes be advantageously employed, and when the membrane is ulcerated, a solution of nitrate of silver will be highly serviceable. The author has used a solution of iodide of potassium Avith advantage, also a weak alcoholic solution of tannic acid. For correcting the fetor of the secretions, a Aveak solution of the chlorinated soda or lime may be occasionally injected into the antrum. In cases of simple muco-purulent secretion, a weak decoction of * In a collection of nearly one hundred superior maxillse, presented to the museum of the Baltimore Dental College by Dr. Maynard, the floor of the antrum Taries in thickness from that of tissue paper to half an inch. DISEASES OF THE MAXILLARY SINUS. 475 galls may be injected into the sinus with advantage. Injections of a too stimulating nature are sometimes employed. This should be care- fully guarded against, by making them at first weak, and afterward increasing their strength as occasion may require; and if symptoms of a violent character are by this means produced, they should be combated by applying leeches to the gums and fomentations to the check. Dependent as these affections in most instances are upon local irri- tants, greater reliance is to be placed on their removal and givino- vent to the acrid puriform fluids, than on any therapeutical effects exerted upon the cavity by injections. As adjuvants, they are ser- viceable, but cure cannot be effected Avhile the exciting cause remains unrein ovcd. The folloAving cases may serve to illustrate the treatment usually pursued in this disease. Case 1. Mrs. T, a married lady, about forty years of age, of a bil- ious temperament, applied to the author for advice in 1853. She had suffered from neuralgic pains in her face and temples, at intervals, for nearly twenty years, and as all of her teeth, especially of the upper jaAV, Avere so much decayed as to preclude the possibility of restora- tion, he urged their immediate removal. She submitted to the opera- tion, hoping that it Avould relieve her from the pain to Avhich she had so long been a martyr, and intending to have the lost organs replaced Avith an artificial set. She called again in a feAV months, partly for this purpose and partly to obtain relief from pain which she still ex- perienced. It Avas not now so much diffused as formerly, but Avas almost Avholly confined to the left side of the face. On inquiry, it Avas ascer- tained that fetid matter Avas occasionally discharged from the nostril of the affected side. This led him to suspect that the antrum Avas diseased. An opening Avas accordingly made through the alveolar border, at the point originally occupied by the second molar. The AvithdraAval of the instrument Avas followed by the discharge of a small quantity of purulent matter. The antrum was now forcibly injected with Avater. This caused the discharge of more than two table-spoon- fuls of hardened flocculi from the left nostril, Avhich, from long con- finement, Avas insufferably offensive. The injection Avas repeated until the antrum Avas completely freed from this accumulation. A solution of sulphate of zinc, in the proportion of six grains to the ounce of water, Avas now substituted. The sinus was injected daily Avith this for a little more than a week, and Avithout any other treatment a complete cure Avas effected. The particulars of the folloAving case are obtained from "Observa- 476 DISEASES OF THE MAXILLARY SINUS. tions of Bordenave on the Diseases of the Maxillary Sinus," a paper embodying reports of forty highly interesting cases. Case 2. " In 1756," says our author, " I was consulted by a lady whose right cheek Avas tumefied. About a month previously she had experienced acute pain under the orbit of the affected side; and she felt a pulsation and heat in the interior of the sinus, and the maxillary bone was slightly elevated. These signs determined me to propose the extraction of the first molar tooth and the perforation of the antrum through the alveolus. The operation Avas folloAved by a discharge of purulent matter, the sinus Avas afterward injected, the maxilla gradu- ally reduced itself, and a cure was effected in about two months." Although injections were employed in the above case, it Avas no doubt the escape of the matter contained in the antrum to which the cure was attributable. As regards the cause that gave rise to the affec- tion in the first instance, not a single Avord is said. It may have re- sulted from inflammation, lighted up in the sockets of one or more teeth, and propagated from thence to the mucous membrane of this cavity, or from inflammation produced by some other cause, and a consequent obliteration of the nasal opening. The following brief statement is taken from the history of a case narrated by Fauchard: Case 3. The child of M. Galois, aged tAvelve years, whose first right superior molar Avas decayed, had a tumor situated anteriorly upon the upper jaw of the same side, extending up to the orbit. M. Fauchard, supposing this tumor, which was about the size of a small egg, had been caused by the carious tooth in question, determined on its extrac- tion as the only means of effecting a speedy and certain cure, and the result proved his opinion correct. The removal of the tooth Avas fol- lowed by a large quantity of yellow serous matter, which, on examina- tion, was found to haA'e escaped from the antrum. The tumor disap- peared soon after the discharge of the matter, and a complete cure was effected. Bordenave, in noticing the foregoing case, does not believe that the tumor communicated with the maxillary sinus, for the reason that the matter escaped through the alveolus of the first molar immediately after its extraction. He, however, admits that the acumen and knowl- edge of Fauchard are such as to have prevented deception in the case. Admitting, then, the statement to be correct — and surely the circum- stance mentioned by Bordenave does not in the least tend to invalidate it, for it is of frequent occurrence — a cure was effected simply by the removal of a decayed tooth, to the irritation produced by which the disease was undeniably attributable. The two following cases are DISEASES OF THE MAXILLARY SINUS. 477 described at length by the last-named author in the "Memoires de l'Academie Koyale de Chirurgie." Case 4. A Avoman, in 1731, had the first superior molar, the croAvn of which had been destroyed by caries, extracted. Not many days after the operation, she was attacked with pain in the upper jaw, which ex- tended from the maxillary fossa to the orbit. The pain was so great as to deprive her of rest; but there was no tumefaction of the cheek or gums. An opening through the alveolus into the sinus Avas discovered, into which a probe was introduced by a surgeon. The withdrawal of this Avas followed by a discharge of yellow fetid matter. M. Lamourier, who Avas afterward consulted, removed from the opening a tooth that had been thrust into the antrum and prevented the egress of the mat- ter, Avhich, by its retention, had become purulent. Injections Avere employed, a part of Avhich, at the expiration of thirty days, escaped from the nasal opening. A perfect cure was soon after effected. In this case, the affection of the sinus was evidently the result of the injury inflicted upon the socket of the first superior molar in an attempt at the extraction of the tooth. The inflammation excited by this, and by the presence of the tooth that had been thrust into the antrum, extended itself to the lining membrane of this cavity, and caused a temporary obliteration of the nasal opening, so that to effect a cure it was necessary to obtain free vent for the retained matter. In restoring to a healthy action the mucous membrane of the cavity, the injections may have been serviceable. Case 5. A girl, aged twenty-six years, had a very much decayed and painful superior dens sapiential on the right side extracted; the tooth was broken, and all the roots but one Avere left in their sockets. These caused an abscess to form; and this was folloAved, for a short time, by a subsidence of the pain, which, hoAvever, soon returned, and a dull, heavy sensation was felt in the antrum of the affected side. From thence the pain extended to the eye and ear. The gums at length became tumefied and the pain less constant; the patient remained in this condition for five years, during which time five teeth were extracted. At this time (1756), M. Beaupreau, Avho Avas consulted, found, on examination, that the gums, where the first tooth had been extracted, had not entirely united, and a small tubercle had formed, from wdiich a fluid of a bad smell and reddish color was discharging itself. He introduced a probe into the fistulous hole of the tubercle, which, after having overcome some obstacle that at first impeded its passage, pene- trated the antrum. The opening was enlarged and mercurial Avater applied to the carious bone; but it soon closed, and the pain, which had ceased, returned. Injections then were resorted to, which dis- charged themselves in part through the nasal opening, and the patient 178 DISEASES OF THE MAXILLARY SINUS. continued in this Avay until an exfoliation of the bone took place, >vhen a cure Avas effected. The cause of the disease in this, as in the preceding cases, was alve- olo-dental irritation, and a cure would at once have been accomplished by the removal of the roots of the tooth that had been left in their sockets; this was proven by the fact that it Avas not until they were thrown off Avith their exfoliated alveoli that the disease was subdued. In alluding to these and similar cases, Bordenave concludes there are not many cases where the extraction of teeth simply will suffice to effect a cure. This inference, to say the least of it, is unfair; for in the case last given, the disease Avas attributable to the presence of the roots of a tooth that had been fractured in an attempt to extract it, and left in their sockets, and Ave have good reason to believe that the cure was wholly owing to their removal. The history of the following exceedingly interesting case, which was communicated to the Faculty of Medicine by Prof. Dubois, is contained in the eighth number of their bulletin for the year 1813, and also in Boyer's work on Surgical Diseases. Case 6. Upon a child between seven and eight years old, at the base of the ascending apophysis of the superior maxillary bone, a small, hard, round tumor of the size of a walnut was perceived by its parents. About a year after, the child fell upon its face, and caused a consider- able discharge of matter from its nose, at the same time bruising the tumor. No other injury was received, and the tumor did not increase perceptibly in size from the eighth to the fifteenth year. During the next year, however, it sensibly augmented, and from the sixteenth to the eighteenth year it attained so great a volume that the floor of the orbit Avas elevated, which caused a diminution in the size of the eye, and restricted the motions of the eyelids. The arch of the palate was depressed, and the nasal fossa almost closed. The nose was forced to the right side of the upper part of the tumor, and there was a consider- able elevation beneath the sub-orbital fossa. The skin below the infe- rior eyelid was of a violet red color, and very tense. The upper lid was elevated, and the gums on the left side protruded beyond those on the other side of the arch. Respiration Avas painful, and the patient spoke with difficulty. Sleep Avas laborious, and mastication was attended with pain. " In this state," says M. Boyer, " he Avas seen by M. Dubois, September 1st, 1802 ; but as he Avas not able to determine on the proper operation, M. Sabatier, M. Pelletan, and himself were called in. It Avas the opinion of all that there was a fungous tumor of the antrum, and for the removal of this, M. Dubois was requested to make choice of his own method of operating." A fluctuation was felt behind the upper lip, and this determined M. DISEASES OF THE MAXILLARY SINUS. 479 Dubois to commence the operation by making an incision there, Avhich was followed by the discharge of a large quantity of glairy, lymphatic substance. Through this opening a sound was introduced into the antrum, and, to M. Dubois' surprise, this cavity contained no tumor; but upon moving the sound about, it struck upon a hard substance, in the most elevated part of the sinus, Avhich, on being removed, proved to be a canine tooth. Preparatory, however, to its extraction, two incisors and one molar were removed and their alveoli cut away. Injections were afterward employed, and the patient was soon restored to health. It is not necessary to stop to inquire how this tooth got into the antrum; aberrations of this- sort in the groAVth of the teeth are fre- quently met with, and some precisely similar instances have already been referred to. In all the cases Avhich have as yet been noticed, the affection was traceable to local irritation, and in all, except the last, it originated in the alveolar ridge. The following'case of muco-purulent engorgement may be thought by some to have been occasioned by a different cause. Yet there are circumstances connected Avith the history of even this case that go to justify the belief that if the teeth had been in a healthy condition the affection would not have existed. Case 7. Mr. G----, a laborer, about thirty years old, of a decidedly scorbutic habit, applied, in the spring of 1834, to an eminent physician of Baltimore, to obtain his advice concerning an affection of the left side of his face, under Avhich he had been laboring for several months. The physician, after having examined the case, came to the conclusion that it Avas mucous engorgement of the maxillary sinus, and requested him to call upon us, and have one of his molar teeth extracted and the floor of the antrum pierced through its alveolus. He at the same time desired, that if his opinion in regard to the nature of the disease proved to be correct, we should take charge of the case altogether. On examining his mouth, AAre discovered that nearly all the teeth of both jaws, the gums and alveoli, were extensively diseased ; and, on inquiry, obtained from him the following statement Avith regard to the commencement and progress of the affection. About six months before this time, having been exposed, while pur- suing his ordinary avocations, to very inclement and changeable Aveather, he contracted a severe cold ; in consequence of this he was confined to his bed for several days, during Avhich time he was tAvice bled, took two cathartics, and other medicines. The disease at first settled in his head, face, and jaws, but at the expiration of eight or ten days Avas subdued by the above treatment, with the exception of the pain in his left cheek, and soreness in the 480 DISEASES OF THE MAXILLARY SINUS. upper teeth of the same side. The pain in his cheek, although not constant, still continued ; the nasal cavity of that side ceased to be sup- plied with its usual secretion, the teeth became more sensitive to the touch ; finally, at the end of four months, a slight protuberance of the cheek was observable, accompanied by a tumor upon the left side of the palatine arch, which, Avhen Ave first saw him, had attained to half the size of a black walnut; and it was by the fluctuation felt here that the physician whom he first consulted Avas induced to suspect the true nature of the disease. Acting in consultation with the medical gentleman in whose care the patient had placed himself, Ave extracted the second left superior molar; then, through its alveolus, penetrated the antrum by means of a straight trocar, after the withdrawal of which a large quantity of glairy, fetid, mucous fluid was discharged. The perforation was kept open by means of a bougie, secured with a slight ligature to an adjoin- ing tooth, as recommended by Deschamps, and the antrum injected three times a day, at first simply with rose-water, to which a small quantity of sulphate of zinc was afterward added. By this treatment the lining membrane of the antrum, at the expiration of five weeks, was restored to health, and the secretions that escaped through the perforation no longer exhaled a fetid odor. The patient, not experiencing any inconvenience, withdrew the bougie, and allowed the aperture to close. In about two months, he again presented himself to the author similarly affected as when we first saAV him. He noAV extracted the first superior left molar and per- forated the antrum through the alveolus, and a quantity of fetid mucous fluid Avas again discharged; the dens sapientiae and the first and second bicuspids of the affected side, being carious, were also extracted. Injections of sulphate of zinc and rose-water, diluted tinc- ture of myrrh, diluted port Avine, and a decoction of nutgalls, Avere alternately employed for three months; at the expiration of this time, the nasal opening, which had been previously closed, Avas re-established, and a perfect cure effected. The condition of the teeth, in the case just narrated, may not be thought to have exerted any agency in the production of the affection of the antrum, but the following considerations would seem to justify a different conclusion. The presence of decayed teeth beneath the sinus may not only have contributed to aggravate the morbid action lighted up by the cold which he had taken, but may also have caused it to locate itself in this cavity; and the fact that the inflammation of the lining membrane and the obliteration of the nasal opening con- tinued until they were removed, would, at least, seem to warrant such an inference. That the injections were beneficial, we do not doubt, DISEASES OF THE MAXILLARY SINUS. 481 but that the cure was effected by them, no one, we think, will dare to affirm. We are far from believing that the presence of the decayed teeth Avas the sole cause of the disease of the antrum; that they con- tributed to, and protracted it, we cannot hesitate to believe; still, but for the increased excitability, and, perhaps, actual inflammation, induced in the mucous membrane by the exposure of the patient to inclement and sudden transitions of Aveather, it is probable the sinus would never have become affected. But, on the other hand, Ave think it not un- likely that, although the disturbance may have originated from this cause, no very serious or lasting morbid effect would have been pro- duced if the teeth and alveoli had been in a perfectly healthy con- dition. The particulars of the following highly interesting case were com- municated to the author by Dr. L. Roper, of Philadelphia, in a con- versation which he had with him in 1845. Case 8. Miss M----, a young lady from the West Indies, about fourteen years of age, had a fistulous opening beneath the right orbit, communicating with the maxillary sinus. By means of a probe intro- duced through the opening into this cavity, the apices of the roots of the first superior molar could be distinctly felt. Medical aid Avas sought at an early stage of the disease, but as no permanent benefit resulted from the treatment adopted, the young lady, at the expiration of nine months, Avas brought by her father to Phila- delphia, and, in the spring of 1831, placed under the care of the late Dr. Physick. He, suspecting that the affection of the antrum had resulted from and Avas still kept up by irritation, produced by the first superior molar of the affected side, which Avas considerably decayed, directed her to be taken to Dr. Roper, Avho, concurring with him in opinion, at once extracted the carious tooth. The operation was fob- lowed by the immediate discharge of a large quantity of thick, muddy, and greenish matter. The fistula under the orbit soon closed, and, Avithout any further treatment, a perfect cure Avas accomplished in the course of a feAv Aveeks. The foregoing are all the particulars which we could obtain concern- ing this interesting case. We have no doubt that, if all the circum- stances connected with its early history were known, it would be found to have resulted from inflammation of the lining membrane of the antrum, caused by irritation in the socket of the tooth Avhich Avas ex- tracted. This opinion is sustained by the facts that this tooth was affected Avith caries, and that its removal was followed by the immedi- ate cure of the disease. In Bordenave's collection of cases of disease of the maxillary sinus, published in the Memoirs of the Royal Academy of Surgery, there are 31 482 DISEASES OF THE MAXILLARY SINUS. several examples similar to the one just narrated. We subjoin a des- cription of the tAvo following: Case 9. A servant of the Count de Maurepas had been afflicted for six months with a fistula upon the left cheek, a little below the orbit, penetrating to the maxillary sinus, and caused by the spontaneous opening of an abscess. The first and second molars, both of which were considerably decayed, were extracted by M. Hevin. As there were no openings through the alveoli, he perforated one with a trocar; this opening gave vent to a great quantity of putrid sanies, and did not close for more than a year after it was made. The fistula of the cheek healed in about ten days. Case 10. In 1717, a soldier of the regiment of Bassigny, who had for a long time a fistula in his cheek penetrating into the maxillary sinus, was treated for it at the Hotel Dieu, of Montpellier. The matter settling near the orifice of the fistula prevented it from closing. M. Lamourier, on examining the mouth of the soldier, perceived that the second superior molar Avas decayed ; this he extracted, and profited by the alveolar cavity to make an opening into the base of the sinus. The fistula of the cheek was by this means cured in a few days, but the coun- ter opening was not immediately permitted to close. In cases of fistula resulting simply from engorgement of the sinus, the treatment should consist, as in the foregoing cases, in the formation of a counter opening, Avhich should always be effected at the most de- pendent part of the cavity; and next in the removal of all sources of local irritation; lastly, in the employment of suitable injections. In the cases thus far presented, we have selected such as were not complicated with abscess, ulceration of the lining membrane, or caries of the surrounding osseous walls; but to the existence of the two last, the affections of which we have been treating, often give rise. For tumors, etc., of the antrum, the reader is referred to tumors of the gums. PART FOURTH. MECHANICS. 488 MECHANICS. THIS branch of dental science teaches the art of replaciug lost organs of the Mouth, or any lost parts thereof. It is sometimes nailed dental Prosthesis (replacement). Mechanical detail is its pre- vailing feature; substitution, or replacement, is its distinctive pecu- liarity. Mechanical detail also distinguishes the Surgery of dentistry as compared with general surgery; but as a branch of dentistry, thera- peusis, or the arrest of disease, is its distinctive peculiarity. . The one treats disease, or irregularity of the natural organs; the other substitutes their loss by artificial ones. Both demand a skilful training of the hands, and equally require, for their fullest develop- ment, all the knowledge comprehended under the term Dental Science. Dental Mechanics includes the laws and principles Avhich determine and regulate the processes employed in the construction of all forms of dental mechanism ; also, the properties and relations of all materials used in these processes. It gives rules for the replacement of 1. Lost teeth. 2. Lo,at alveoli, or parts thereof. 3. Lost palate, hard and soft, or parts thereof. The first division is the most important because the most universally demanded. Prof. Austen gives the following order of operations in the Re- placement of Lost Teeth, and classification of the various styles of Avork. 1. Preparation of the mouth ; including (a) Treatment of the mucous membrane. (b) Extraction, or treatment of teeth and roots. 2. Impression of the mouth; including (a) Form and material of impression cups. (b) Description of impression materials. (c) Selection and manipulation of the same. (d) Preparation for the model. 485 486 MECHANICS. 3. The plaster model; including (a) General directions for making model. (6) Special forms adapted to subsequent uses. (c) Removal from impression. (d) Preparation for the operation of making the plate. 4. The base-plate; which is either (a) Permanent, in swaged work, or (b) Temporary, in plastic Avork. The subsequent operations differ in their order and character so widely as to require a separate classification in (A) Swaged work: (1) Metallic die and counter-die, made by (a) Sand moulding; (b) Dipping, or pouring; (c) Fusible metal process, or by (d) Pouring directly into the impression. (2) Refining and rolling plate. (3) Swaging plate (gold, silver, platinum, or aluminum). (4) Articulating impressions. (5) Adjustment on articulator. (6) Selection and fitting of teeth, and (7) Attaching them to base-plate, by (a) Soldering; (b) Vulcanite; (c) Porcelain continuous gum. (8) Finishing process. (B) Plastic work: (1) Temporary plate of (a) Wax, or gutta-percha ; (b) Thick tin, or lead, foil. (2) Articulating impressions. (3) Adjustment on articulator. (4) Selection and fitting of teeth. (5) Preparation of the matrix. (6) Moulding and hardening of the base-plate, made of (a) Vulcanite compounds which harden by heat; (b) Molten tin alloys wdiich harden on cooling; (c) Molten aluminum; (7) Which process at the same time attaches the teeth. (8) Finishing process. The details of SAvaged work vary according to the mode of making dies, the metal chosen for the plate, and the manner of attaching the teeth; but the order of operations is the same. The details of MECHANICS. 487 Plastic work vary also according to the material composing the plate; but the order of operations is the same — differing from the former mainly because articulation follows the formation of the base-plate in one case^ while in the other it precedes it. These differences in the material of the base-plate give rise to a classification of Swaged work into 1. Gold plate; 2. Aluminum plate; 3. Platinum plate. The first (and third) allows attachment of the teeth by soldering; the second demands a vulcanite attachment; the third alone permits, by virtue of its resistance to furnace heat, the addition of a continuous porcelain gum. Plastic work is divided into 1. Vulcano-plastic; 2. Metallo-plastic; 3. Ceramo-plastic. The first is knoAvn as rubber work ; the second includes cheoplastic work, the old-fashioned block tin-base, all tin alloys and cast aluminum; the third is known as the porcelain base. In Prosthetic dentistry, swaged Avork is the patrician element; plastic Avork, the plebeian. When the latter runs riot, Avithout the conservative influence of the former, the power of the people becomes a poAver for evil. This is precisely the danger which now threatens dentistry, in the abuse of certain most valuable processes and materials. Facility of construction and cheapness of material have encouraged a style of practice in the highest degree detrimental to the profession. If such practice is inseparable from plastic work, it should be unhesi- tatingly abandoned by every one Avho holds the honor of dentistry dear to him. It becomes also a grave question how far the present mania for patents (another abuse of a valuable privilege) is beneficial to the reputation of a liberal profession. 488 DENTAL PROSTHESIS. CHAPTER I. DENTAL PROSTHESIS. CONTRIBUTING, as the teeth do, to the beauty and expression of the countenance, to correct enunciation, and, through improved facility of mastication, to the health of the whole organism, it is not surprising that their loss should be considered a serious affliction, and that art should be called upon to replace such loss with artificial sub- stitutes. So great, indeed, is the liability of the human teeth to decay, and so much neglected are the means of their preservation, that few persons, at the present day, reach even adult age Avithout losing one or more of these invaluable organs. Happily for suffering humanity, they can noAV be replaced with artificial substitutes so closely resembling the natural organs as to be readily mistaken for them, even by critical and practised observers. Although there is a perfection in the work of nature that can never be equalled by art, artificial teeth are noAV so constructed as to subserve, at least to a great extent, the purposes of the natural organs. When properly adjusted, they are Avorn Avithout the slightest discomfort; so much so, in many cases, that the patient, after they have been in the mouth a few weeks, is scarcely conscious of their presence. The construction of artificial teeth is an operation Avhich, though acknowledged to be of great importance, and performed by every one having any pretension to a knowledge of dentistry, is, unfortunately, but little understood by the majority of practitioners. The mouth is often irreparably injured by their improper application. A single arti- ficial tooth, badly inserted, may cause the destruction of the two adja- cent natural teeth, or those to Avhich the artificial appliance is secured ; and if the deficiency thus occasioned be unskilfully supplied, it may cause the loss of others; in this Avay all the teeth of the upper jaAV are sometimes destroyed. The utility of artificial teeth depends upon their proper construction and correct application. There is no branch of dental practice that requires more skill and judgment, or more extensh^e and varied scien- tific information. A knowledge of the anatomy and physiology of the mouth, of its various pathological conditions, and their therapeutical indications, is as essential to the mechanical as to the surgical dentist. To correct information upon these subjects must be added the ability to execute, with the nicest skill and most perfect accuracy, all the mechanism required in dental prosthesis. DENTAL PROSTHESIS. 489 There are difficulties connected with the insertion of artificial teeth of Avhich none but an experienced dentist has any idea. They must be constructed and applied in such a manner that they may be easily re- moved and replaced by the patient; at the same time they must be securely fixed in the mouth, and be productive of no injury to the parts with which they are in relation. But perfect mechanism is not the sole element of success : often it is not the most essential one. To know when to extract and Avhen to re- tain a root or a tooth ; Avhen to secure a piece by clasps and Avhen by simple adaptation ; when to use gold and when some other material; to determine the best form of a plate and the proper time for its insertion; finally, to determine Avhen and what prosthetic skill can do, when and why it will fail — are a few of the problems in dental me- chanics Avhich demand for their correct solution a fulness and extent of information Avhich are not always brought to bear ; perhaps because, unfortunately, the necessity is not recognized as it should be. Notwithstanding the triumphs of prosthetic dentistry, and the high state of excellence to Avhich it has arrived, at no previous time was there ever so much injury inflicted, and suffering occasioned by arti- ficial teeth, as at present,—resulting solely from their bad construc- tion and incorrect application. That such should be the case, Avhen there are so many scientific and skilful dentists in every city and in many of the villages of the country, may seem strange, but the fact is nevertheless undeniable. We may explain it in part by the very rapidly increasing demand for dental services, which has not allowed time for the development of intelligent and skilled labor either of head or hand ; in part also by the universal experience that all neAV professions are full of immature and crude material. But these explanations cannot long be received in excuse for a state of things Avhich ought to be rapidly disappearing; which is in fact giving Avay under the combined influ- ence of our colleges, our periodicals and text-books, the teachings and example of our eminent practitioners, and the more appreciative judg- ment of the public. These remarks apply alike to the surgery and mechanism of dentis- try. The latter has an additional barrier to progress in the common practice of delegating the greater part of its details to inexperienced, uninformed and irresponsible assistants. Perfect dentistry demands equal skill and education in both departments. Each requires that its complete series of operations shall be the work of one person. If therefore the Avork of the two are so far incompatible that they cannot be combined, the separation should be complete. The semi-mechanism of the surgeon is like the semi-surgery of the mechanician. Each * 490 DENTAL PROSTHESIS. injures an otherwise perfect reputation; both do harm to the profession they seek to honor. The information obtainable from works on mechanical dentistry was until recently exceedingly limited; and it is surprising, that from the number Avho have written on the diseases and loss of the teeth, this subject should have received so little attention. Fauchard, Bourdet, Angermann, Maury, Delabarre, Koecker, Lefoulon, BroAvn, and a few others, are all who, until within a few years past, have given it any- thing more than a passing notice; and the works of these writers con- tain feAv explicit directions upon the subject. Delabarre's Mechanical Dentistry was, at the time of its publication, a work of much merit. The various methods adopted at that period for the construction and application of artificial teeth are accurately and minutely described, together with the advantages and disadvantages of each. But, how- ever perfect the work may then have been, it does not furnish the in- formation required upon the subject at the present day. Still more deficient in correct information are nearly all other French works. Among the English writers, Koecker is almost the only one, except Robinson, a more recent author, who has described correctly the prin- ciples upon which artificial teeth should be applied. His " Essay on Artificial Teeth,. Obturators and Palates," contains much useful and valuable information. It does not, however, contain a description of the manner of constructing a dental substitute, preparatory to its appli- cation ; yet, to one capable of executing the various manipulations re- quired in this department of practice, it is very serviceable. Dr. Koecker, perhaps, thought that, as this ability can only be acquired by a regular apprenticeship, a more minute description was unnecessary. There are many practitioners, hoAvever, who, although in other respects competent, have not, in the mechanical department, enjoyed this advan- tage, and, consequently, it is to be regretted that he has not entered more into detail upon the subject. Most of the deficiencies that exist in the last-named work were supplied, up to 1844, by Dr. Solyman Brown, in his series of papers on Mechanical Dentistry, published in the American Journal of Dental Science. These papers were illustra- ted with numerous cuts, and constituted, up to the time of their publi- cation, the best treatise upon the subject. But numerous and important improvements have subsequently been made in this department of practice, all of which we propose to give a brief description of in their proper place. The only treatises upon Mechanical Dentistry, published in book form, in this country, since the papers of Dr. BroAvn, have been this division of our oavh work and the treatise of Prof. Joseph Richardson. In the dental periodicals of the past eighteen years will be found many SUBSTANCES EMPLOYED AS SUBSTITUTES. 491 carefully prepared papers from the pen of Prof. Austen, and others, which present a great amount of information, very valuable to the practitioner. They give also an instructive view of the rapid progress made in the dental art, and teach the necessity of being constantly alive to the improvements, real or fancied, which are almost daily pro- posed. We shall enumerate some of the different kinds of dental substitutes that have been employed since the commencement of the present cen- tury. We shall also notice, briefly, the principal methods that have been adopted in their application, before entering upon a minute description of those practised at the present time. Great improvements have been made in dental prosthesis since the publication of the first edition of this work. In fact no science or art, except Chemistry, has been so eminently progressive during the last twenty years as Mechan- ical Dentistry. CHAPTER II. SUBSTANCES EMPLOYED AS DENTAL SUBSTITUTES. THERE are two qualities which it is highly important that dental substitutes should possess. They should be durable in their nature; and in their appearance should resemble the natural organs which they replace or with which they are associated. The kinds of teeth that have been employed, since 1820, are: 1. Human teeth. 2. Teeth of neat cattle, sheep, etc. 3. Teeth carved from the ivory of the elephant's tusk, and from the tooth of the hippopotamus. 4. Porcelain teeth. HUMAN TEETH. As regards appearance, Avhich in a dental substitute is an important consideration, human teeth are preferable to any other, except, perhaps, the almost perfect recent productions of the dento-ceramic art. When used for this purpose, they should be of the same class as those the loss of Avhich they are to replace. The crowns only are employed, and if Avell selected and skilfully adjusted, the artificial connection Avith the alveolar ridge cannot easily be detected. The durability of these teeth Avhen thus employed depends upon the density of their texture, the soundness of their enamel, and the condi- tion of the mouth in which they are placed. If they are of a dense 492 SUBSTANCES EMPLOYED AS SUBSTITUTES. texture, with sound and perfect enamel, and are placed in a healthy mouth, they will last from eight to twelve years, or even longer. The difficulty, however, of procuring these teeth is generally so great that it is seldom that such as Ave have described can be obtained ; and even when they can, the mouth, in half the cases in which artificial teeth are placed, is not in a* healthy condition; its secretions are often so vitiated and of so corrosive a nature, that they destroy them in less than four years. We have even known them to be destroyed in two, and in one case in fifteen months. A human tooth, artificially applied, is more liable to decay than one of equal density having a vital connection with the general system, for the reason that its dentinal structure is more exposed to the action of deleterious chemical agents. Yet of all the animal substances em- ployed for this purpose, human teeth are unquestionably the best. They are harder than bone, and being more perfectly protected by enamel, are consequently more capable of resisting the action of cor- rosive agents. Many object to having human teeth placed in the mouth, under the belief that infectious diseases may be communicated by them. But the purifying process, to which they are previously submitted, greatly diminishes this danger. When the practice of transplanting teeth was in vogue, occurrences of this sort were not unfrequent; but since that has been discontinued, these have seldom if ever happened. Still, the prejudice against human teeth is so strong that it is impossible, in most cases, to overcome them. This feeling, the difficulty of procuring them, the high price they command, and their Avant of durability, have gradually led to their entire disuse, which is scarcely to be re- gretted, now that art can produce in porcelain such accurate imitations of nature. The only case in which we might feel called upon to insert natural teeth is where any of the tAvelve front teeth become loosened by periosteal disease, and drop from their sockets while yet perfectly free from caries. These teeth may often be adjusted to a plate so as to present an exceedingly natural appearance. TEETH OF CATTLE. Of the various kinds of natural teeth employed for dental substu tutes those of neat cattle are, perhaps, after human teeth, the best. By slightly altering their shape they may be made to resemble the incisors of some persons; but a configuration similar to the cuspids cannot be given to them, and in most cases they are too white and glossy. The con- trast, therefore, Avhich they form with the natural organs should consti- tute, were they in all other respects suitable, a very serious objection to their use. Imitation of nature has been too much disregarded, both SUBSTANCES EMPLOYED AS SUBSTITUTES. 493 by dentists and patients. Indeed, many of those who need artificial teeth wish to have them as white and brilliant as possible, and some practitioners lack either the decision or the judgment to refuse com- pliance with a practice Avhich destroys all that beauty and fitness Avhich it is the aim of dental aesthetics to cultivate. There are other objections to the use of these teeth. In the first place, they are only covered anteriorly with enamel; in the second, their dentinal structure is less dense than that of human teeth, and. consequently, they are more easily acted on by chemical agents. They are, therefore, less durable, seldom lasting more than from two to four years. Another objection to their use is, they can be employed in only the very few cases where short teeth are required, owing to the large size of their nerve cavities. It is seldom, therefore, that they can be advantageously used as substitutes for human teeth. IVORY OF THE ELEPHANT AND HIPPOPOTAMUS. Artificial teeth made from the ivory of the tusk, both of the elephant and hippopotamus, have been sanctioned by usage from the earliest periods of the existence of this branch of the art. We must not hence conclude that it has been approved by experience; on the contrary, of all the substances that have been used for this purpose this is cer- tainly the most objectionable. The ivory of the elephant's tusk is decidedly more permeable than that obtained from the hippopotamus. So readily does it absorb the buccal fluids that, in three or four hours after being placed in the mouth, it becomes completely saturated Avith them. Consequently, it is not only liable to chemical changes, but the absorbed secretions undergo decomposition ; and when several such teeth are worn, they affect the breath to such a degree as to' render it exceedingly offensive. Again, on account of its softness, teeth are easily shaped from it; but not being covered with enamel, they soon become dark, and give to the mouth a repulsive appearance. Fortunately, hoAvever, in the United States, elephant's ivory is rarely used, either as a base-plate or for the teeth themselves. The ivory of the tusk of the hippopotamus is much firmer in its texture than that obtained from the elephant; being covered with a hard, thick enamel, teeth may be cut from it, Avhich, at first, very closely resemble the natural organs. There is, hoAvever, a peculiar animation about human teeth, which those made from this substance do not possess : moreover, they soon change their color, assuming first a yelloAV and then a dingy bluish hue. They are, also, like elephant ivory, very liable to decay. We have in our possession a number of blocks of this sort, some of which are nearly half destroyed. The 494 SUBSTANCES EMPLOYED AS SUBSTITUTES. same objection lies against teeth made from the hippopotamus ivory sufficient to condemn its use. Like those formed from elephant ivory, they give to the breath an offensive odor, which no amount of care or cleanliness can wholly correct or prevent. PORCELAIN, OR INCORRUPTIBLE TEETH. The manufacture of porcelain teeth did not for a long time promise to be of much advantage to dentistry. But through the ingenuity and indefatigable exertions of a few, they have within the last thirty years been brought to such perfection as to supersede all other kinds of arti- ficial teeth. The French, with whom the invention of these teeth originated, encouraged their manufacture by favorable notices; and the reAvards offered by some of the learned and scientific societies of Paris con- tributed much to bring it to perfection. They Avere still, however, deficient in so many particulars that they received the approbation of very few of the profession, and then only in some special cases. It is principally to American dentists that we are indebted for that which the French so long labored in vain to accomplish. A want of resemblance to the natural organs, in color, translucency, and animation, was the great objection urged against porcelain teeth ; and, had not this been obviated, it would have constituted an insuper- able objection to their use. Until 1833, all that were manufactured had a dead, opaque appearance, Avhich rendered them easy of detection, when placed beside the natural teeth, and gave to the mouth an unna- tural aspect. But so great have been the improvements in their manufacture, that few can now distinguish between the natural teeth and their artificial companions, if well selected and skilfully applied. The advantages which mineral teeth possess over every sort of animal substance are numerous. They can be more readily secured to the plate, and are worn with greater convenience. They do not absorb the secretions, and, consequently, when proper attention is paid to their cleanliness, they do not contaminate the breath, or become in any way offensive. Their color never changes. They are not acted on by the chemical agents found in the mouth, and hence the name incor- ruptible, Avhich has been given them. The objections that have been urged to the use of porcelain teeth — such as Avant of congeniality between them and the mouth, their better conducting power, and their consequent greater liability to the action of heat and cold—have so little foundation, that, when compared with the advantages they confessedly possess, they must be regarded as unworthy of consideration. The vast extension of mechanical practice is due, more than to any other one cause, to these improvements in the RETENTION OF ARTIFICIAL TEETH. 495 manufacture of porcelain teeth, —improvements essentially American and so important as fairly to justify a little of that boasting spirit which, transplanted from the mother country, has attained such luxu- riant groAvth in American soil. The beautifully exact imitation of the varying shades of the natural gum, which as yet has been found possible only in porcelain, would of itself give to this material a claim over every other. All attempts to color ivory have failed to produce any permanent results. More recent experiments in the several vulcanizable materials have thus far given opaque and lifeless colors, which no stretch of the imagination can compare with the natural gum. When a material shall have been discovered possessing the valuable properties of the vulcanite com- bined with the beauty of a porcelain artificial gum, dental prosthesis will have nearly reached perfection. CHAPTER ILL RETENTION OF ARTIFICIAL TEETH. THE methods of retaining artificial teeth in place are— first by pivoting to the natural roots; second, by attaching to metallic or other kind of base-plate, secured either by, 1, clasps; 2, spiral springs; or, 3, atmospheric pressure. The peculiar advantages of each of these methods we shall now proceed to point out, and the cases to Avhich they are particularly applicable. ARTIFICIAL TEETH PLACED ON NATURAL ROOTS. This method of securing artificial teeth was, until recently, on ac- count of its simplicity, more extensively practised than any*other; and, under favorable circumstances, is unquestionably one of the best that can be adopted. If the roots on which they are placed be sound and healthy, and the back part of the jaAvs supplied with natural teeth, so as to prevent those Avith Avhich the artificial antagonize from strik- ing them too directly, they will subserve the purposes of the natural organs more perfectly than any other description of dental substitute, and can be made to present an appearance so naturalas to escape detection upon the closest scrutiny. If properly fitted and secured,. not only is their connection Avith the natural roots not easily detected, but they may render valuable service for many years. The incisors aud cuspids of the upper jaw are the only teeth which it is proper to replace in this Avay. 496 RETENTION OF ARTIFICIAL TEETH. The lower incisors, from their small size and the dangerous sequelae of abscess, should never be pivoted. Many upper laterals are also too small to admit a pivot. In practice, the pivoting of cuspids is seldom called for. These teeth being very persistent, their loss usually im- plies that of many, perhaps all, others, and the entire deficiency is replaced by teeth attached to a base-plate. The insertion of an artificial tooth on a diseased root, or on a root having a diseased socket, is almost always followed by injurious con- sequences. Filling the root, together with proper accompanying treat- ment, will sometimes so completely arrest disease as to make pivoting safe; but there is always risk in these cases. The morbid action already existing in the root, or its socket, is aggravated by the operation, and often caused to extend to the contiguous parts, and occasionally even to the whole mouth. Even in a healthy root, it is not always proper to apply a tooth immediately after having prepared the root. If any irritation is produced by this preparatory process, the tooth should not be inserted until it has wholly subsided. The neglect of this pre- caution not unfrequently gives rise to inflammation of the alveolo- dental periosteum and to alveolar abscess. Apart from the condition of the root, the question of pivoting — or of a plate tooth without gum, resembling a pivot tooth — may de- pend upon the adjoining tooth or roots. If, in any space to be sup- plied, one root is absent, all should be extracted, for the peculiar beauty of a pivot tooth is lost if its neighbor has an artificial gum. Although this method of securing artificial teeth has received the sanction of the most eminent dental practitioners, and is one of the best that can be adopted for replacing loss in the six upper front teeth, yet, on account of the facility with Avhich the operation is performed, it is often resorted to under the most unfavorable circum- stances; in consequence of Avhich, the method has been undeservedly brought into discredit. Apart from the proneness of operators to resort to this method when its adoption is unjustifiable, we may name two objections to the use of pivot teeth, as ordinarily prepared and inserted. First, the difficulty of preventing the presence of secretions between the crown and root, Avhich make the breath offensive and cause the root gradually to decay. Secondly, the more or less rapid enlargement of the canal requiring frequent replacement and the ultimate loss of the root. The efforts of the economy for the expulsion of the roots of the bicuspid and molar teeth, after the destruction of their lining mem- brane, are rarely exhibited in the case of roots of teeth occupying the anterior part of the mouth. This circumstance has led us to believe that the roots of these teeth receive a greater amount of vitality from RETENTION OF ARTIFICIAL TEETH. 497 their investing membrane than do the roots of those situated farther back in the mouth; and that the amount of living principle thus applied is sufficient to prevent them from becoming manifestly ob- noxious to their sockets. Another explanation assumes the equal vitality of all the roots, and attributes the persistence of front roots, upon which a crown has been placed, to the continuance of that pressure to AA'hich it was sub- ject so long as it had its natural crown. It is asserted, in mainten- ance of this view, that front roots, left to themselves, will disappear in the same manner as bicuspid and molar roots, and that the latter may be retained, if the artificial crown (attached to a plate) is set upon them ; also, that the process of expulsion is analogous to that by which a tooth is elongated, which has lost its antagonist. It is well known that a dead root is always productive of injury to the surrounding parts, and that nature calls into action certain agen- cies for its expulsion. Therefore, attaching a tooth to a completely dead root is manifestly improper; but the roots of the front teeth are rarely entirely deprived of vitality, and hence, after the destruction of their lining membrane, they often remain ten, fifteen, and sometimes tAventy years, without very obviously affecting the adjacent parts. Teeth attached to a plate and resting upon natural roots have all the beauty which so strongly recommends pivot teeth. They are not so securely held in position ; but the ability to remove them is in itself an advantage. This method is applicable in many cases where the drilling for a pivot is impossible. It is perhaps preferable to a pivot tooth, in all cases where the absence of other teeth calls for a plate. ARTIFICIAL TEETH SECURED BY CLASPS. This method of inserting artificial teeth, first introduced by the late Dr. James Gardette, of Philadelphia, is, perhaps, in favorable cases, one of the firmest and most secure that can be adopted. By this means, the loss of a single tooth, or of several teeth, may be supplied. A plate may be so fitted to a space in the dental circle, and secured with clasps to other teeth, as to afford a firm support to six, eight, or ten artificial teeth. Teeth applied in this way, when properly constructed, will last for several years, and sometimes during the life of the individual. But it is essential to their durability that they should be correctly arranged, accurately fitted, and firmly secured to the plate; that the plate itself be properly adapted to the gums, and the clasps attached Avith the utmost accuracy to teeth firmly fixed in their sockets. Gold is perhaps the best material that can be employed for both plate and clasps. Since the application of vulcanized rubber to. dental 32 498 RETENTION OF ARTIFICIAL TEETH. purposes, plates of this latter material with gold clasps attached have been much used. When gold is employed for the plate it should be from tAventy to twenty-one carats fine, and from eighteen to nineteen for the clasps. If gold of an inferior quality is used, it will be liable to be acted on by the secretions of the mouth. Platina perfectly resists the action of these secretions, and Avould, perhaps, answer the purpose as well as gold, Avere it not for its softness and pliancy: in full cases, and in some partial cases, the shape of the plate may, more or less, overcome this difficulty, especially when, as in the continuous gum Avork, stiffened by other materials. The plate should be thick enough to afford the necessary support to the teeth ; but not so thick as to be clumsy or inconvenient from its Aveight. The clasps generally require to be about one-third or one-half thicker than the plate, and sometimes double the thickness. The gold used for this purpose is sometimes prepared in the form of half-round wire; but, in the majority of cases, it is preferable to have it flat, as such clasps afford a firmer and more secure support to artificial teeth than those which are half-round ; they also occasion less inconvenience to the patient, and are productive of less injury to the teeth to which they are-attached. Artificial teeth, applied in this way, may be worn with great comfort, and can be taken out and replaced at the pleasure of the person wearing them. It is important that they should be very frequently cleansed, to remove the secretions of the mouth that get between the plate and gums and between the clasps and teeth, which, becoming vitiated, may irritate the soft parts and corrode the teeth and taint the breath. This precaution should, on no account, be neglected. Great care, therefore, should be taken to fit the clasps in such a manner as will admit of the easy removal and replacement of the piece, and, also, that they may not exert any undue pressure upon the teeth to which they are applied. If the clasp, in consequence of inaccurate adjustment, strains the position of the tooth in its socket, it may excite inflammation in the alveolo-dental periosteum, and the gradual destruction of the socket Avill follow as a natural consequence. Also, if the clasp press too closely upon the neck of the tooth, it may develop a morbid sensibility in the cementum, causing great annoyance, and possibly exciting inflamma- tion and alveolar absorption or loosening of the tooth. Several years since, Dr. Goodall obtained a patent for a method of retaining partial sets of artificial teeth by elastic or spring plates of vulcanized rubber, the utility of which, indiscriminately applied, as well as the validity of the patent, some are disposed to doubt, contend- ing that these plates differ but little from metallic ones formerly in RETENTION OF ARTIFICIAL TEETH. 49? use, constructed in the same manner, and described as partial or stay- clasps. This form of clasp, instead of embracing the natural tooth, simply presses against the inner surface of the contracted portion of the crown near the gum with a force which is sufficient to keep the substitute in place. Prof. Austen's method of taking plaster impressions in partial cases was designed by him, in 1858, with special reference to obtaining an accurate copy of the inner surface of bicuspids and first molars. Accu- rate fitting of the vulcanite plate against one or two such teeth on each side prevents lateral motion, and gives great stability to the piece. It takes the place of the vacuum cavity with much better results ; in fact, he regards this form of stay-plate essential to every partial piece not clasped, whilst he regards the cavity Avorse than useless. ARTIFICIAL TEETH WITH SPIRAL SPRINGS. The difference between the method last noticed, of applying artificial teeth, and the one now to be considered, consists in the manner of con- fining them in the mouth. The former is applicable in cases where there are other teeth in the mouth to Avhich clasps may be applied: the latter is designed for confining a double set; more rarely a single set or part of a set. When plates with spiral springs are used, the teeth are attached to them in the same manner as when clasps are em- ployed ; but instead of being fastened in the mouth to other teeth, they are kept in place by means of the spiral springs, lying one on each side of the artificial dentures between them and the cheeks, passing from the upper piece to the lower. Spiral springs were formerly much used, and although various other kinds of springs have been used, none seem to answer the purpose as well as these. When they are of the right size, and attached in a proper manner, they afford a very sure and convenient support. They exert a constant pressure upon the artificial pieces, Avhether the mouth is opened or closed. They do not interfere Avith the motions of the jaAV, and, although they may at first seem awkward, a person will soon become so accustomed to them, as to be almost unconscious of their presence. They are, however, liable to derangement from accident; they make the piece aAvkward to handle in the necessary daily cleans- ing ; they retain the secretions offensively; and not unfrequently are a source of much irritation to the cheek. It is therefore a subject of congratulation that successive improve- ments in the process of adapting the plate to the mouth have gradually lessened the number of cases in Avhich spiral springs are thought neces- sary. It is iioav rare to meet Avith a case in which they are absolutely 500 RETENTION OF ARTIFICIAL TEETH. essential for the permanent retention of the piece. Occasional use is made of them for the temporary retention of a piece made soon after extraction, in Avhich the plate is designedly made more even than the irregular alveolar border; which plate cannot of course fit the mouth, until the inequalities of the gum have yielded to the pressure of the plate. TEETH RETAINED BY ATMOSPHERIC PRESSURE. The method last described,, of confining artificial teeth in the mouth, is often inapplicable, inefficient, and troublesome, especially for the upper jaAV; in such cases, the atmospheric pressure, or suction method, is very valuable. It Avas, for a long time, thought to be applicable only to an entire upper set, because it was supposed that a plate suffi- ciently large to afford the necessary amount of surface for the atmos- phere to act upon could not be furnished by a piece containing a smaller number of teeth. Experience, however, has proved this opinion to be incorrect. A single tooth may be mounted upon a plate presenting a surface large enough for the atmosphere to act upon for its retention in the mouth; but, when only a partial upper set is required, it is often more advisable to secure the piece by means of clasps. For a like reason, it was thought that the narrowness of the inferior alveolar ridge would preclude the application of a plate to it upon this principle, and in this opinion the author once coincided ; but he has succeeded so perfectly in confining lower pieces by this means, that he noAV never finds it necessary to employ spiral springs for their retention. The principle upon which this plan is founded may be simply illus- trated by taking two small blocks of marble or glass, the flat surfaces of which accurately fit each other. If now the air between them is replaced by water, the atmospheric pressure upon their external sur- faces will enable a person to> raise the under block by lifting the upper. Upon the same principle, a gold plate, or any other substance impervi- ous to the atmosphere, and perfectly adapted to the gums, may be made to adhere to them. The firmness of the adhesion of the plate or base to the gums depends on the accuracy of its adaptation. If this is perfect, it will adhere with great tenacity ; but if the plate is badly fitted, or becomes warped in soldering on the teeth, its retention will often be attended Avith diffi- culty. It is also important that the teeth should be so arranged and antagonized, that they shall strike those in the other jaAV on both sides at the same instant. This is a matter that should never be overlooked, for if they meet on one side before they come together on the other, the part of the plate, or base, not pressed upon, may be detached, and by admitting the air betAveen it and the gums, cause it to drop. RETENTION OF ARTIFICIAL TEETH. 501 Since, in the act of mastication, pressure is made on one side, with no counter-pressure on the other, this inequality will not necessarily detach a well-made piece. But when the upper-molars are set so far from the median line of the mouth that the line of pressure falls outside the alveolar ridge, it is difficult to retain the best-fitting piece in place during mastication. It is also of utmost importance that, by proper selection of the im- pression material, and judicious management of subsequent processes, the plate should bear upon the ridge more than upon the palate. In doing this, however, no more space should be left than a few days' wear will obliterate, giving absolute contact over the entire surface. For there is no kind of space, cavity, or chamber Avhich gives so complete a vacuum as contact, or which secures such permanently useful adhe- sion of the plate. The application of artificial teeth on this principle has been prac- tised for a long time. Its practicability was first discovered by the late Mr. James Gardette, of Philadelphia. But the plates formerly used were ivory instead of gold, and could seldom be fitted with sufficient accuracy to the mouth to exclude the air; so that, in fact, it could hardly be said that they Avere retained by its pressure; except in that class of cases in which the mouth, by virtue of a soft membrane, has power to adapt itself to the plate. Unless fitted in the most perfect manner, the piece is constantly liable to drop; and the amount of sub- stance necessary to leave in an ivory substitute renders it so awkAvard arid clumsy that a set of teeth mounted upon a base of this material can seldom be Avorn with much comfort or satisfaction. The firmness Avith which teeth applied upon this principle can be made to adhere to the gums, and the facility with which they can be removed and replaced, renders them, in many respects, more desirable than those fixed in the mouth Avith clasps. But, unless judgment and proper skill are exercised in the construction of the work, a total failure may be expected, or, at least, the piece will never be worn with satisfaction and advantage. There Avere feAV Avriters, at the time of the publication of the first edition of this Avork, Avho had even adverted to this mode of applying artificial teeth. Drs. L. S. Parmly and Koecker had each bestowed on it a passing notice. The former, in alluding to the subject, thus remarks: " Where the teeth are mostly gone in both or in either of the jaws, the method is, to form an artificial set by first taking a mould of the risings and depressions of every point along the surface of the jaw.s, and then making a corresponding artificial socket for the whole. If this be accurately fitted, it will, in most cases, retain itself 502 RETENTION OF ARTIFICIAL TEETH. sufficiently firm, by its adhesion to the gums, for every purpose of speech and mastication." Dr. Koecker tells us that he has " been completely successful in several instances, in the application of sets for the upper jaw in this manner; they should be made either of gold plate mounted Avith natural or artificial teeth, or of one piece of hippopotamus tooth." Having already stated the objections that exist to the use of the latter sub- stance, Ave cannot join with Dr. K. in its recommendation. At the time when we first substituted the gold plate for ivory, we had not seen his late work on artificial teeth, and consequently AVere not aAvare that the use of metal for a base had ever before been recommended. Modifications of the atmospheric pressure principle have been made since 1845, by constructing the plate Avith an air-chamber or cavity, so that when the air is exhausted from betAveen it and the parts against which it is placed, a more or less complete vacuum is formed, causing it to adhere when first introduced with greater tenacity to the gums than a base fitted without such cavity. This modification might be termed an improvement, Avere it not that its introduction has become so unnecessarily general, has so often induced a diseased condition of the mucous membrane, and has led to a slovenly, careless method of swaging and fitting plates. For these and some other reasons, Prof. Austen regards its introduction as a positive detriment, at the same time that he acknowledges its occasional utility. He argues that theory and practice alike condemn the use of a cavity for the perma- nent retention of any piece; and suggests for its temporary reten- tion, Avhilst the work is going through its stage of adaptation, some other plan than this permanent disfigurement. The so-called vacuum cavity can, at best, be only partially a vacuum, hence cannot give the amount of atmospheric pressure that perfect contact will. So long as it acts in the retention of a piece, it necessarily draws the yielding membrane into the space, and must ultimately fill it. When this is done, the piece is evidently retained by the "vacuum of contact." If, in any case, the mouth does not show the size and depth of the cavity imprinted on the palate, it proves that the vacuum force is not exerted, and that the piece is retained by contact of the parts around the cavity. In these cases, of constant occurrence, the cavity diminishes the adhesion of the plate, and can only be of service Avhere it helps to remove pressure from a hard palate. But as this can be done in a better way, it is no argument in favor of the cavity. The only cases in which this chamber is permanently useful are very flat mouths with scarcely any perceptible ridge. A sharply de- fined cavity, varying in depth from one-half to one line, according to PREPARATORY TREATMENT OF THE MOUTH. 503 the softness of the membrane, when filled by this membrane,tendsto prevent that lateral motion of the piece so troublesome in "such cases. Partial pieces not retained by clasps, or the lateral pressure of stays, or their closeness of adaptation, are never permanently improved by the cavity. Even in pieces made soon after extraction (so unfortu- nately named temporary sets), the temporary action of the cavity is of very questionable utility. CHAPTER IV. PREPARATORY TREATMENT OF THE MOUTH. THE condition of the mouth is not sufficiently regarded in the application of artificial teeth, and to the neglect of this the evil effects that so often result from their use are frequently attributable. An artificial appliance, no matter how correct it may be in its con- struction and in the mode of its application, cannot be worn Avith impunity in a diseased mouth. Of this fact, every day's experience furnishes the most abundant proof. Yet there are men in the profes- sion so utterly regardless of their own reputation, and of the conse- quences to their patients, as wholly to disregard the condition of the mouth, and are in the constant habit of applying artificial teeth upon diseased roots and gums, or before the curative process, after the extraction of the natural teeth, is half completed. The dentist, it is true, may not always be to blame for omitting to employ the means necessary for the restoration of the mouth to health. The fault is often Avith the patient. There are many who, after being fully informed of the evil effects Avhich must of necessity result from such injudicious practice, still insist on its adoption. But the dentist, in such cases, does Avrong to yield his better informed judgment to the caprice or timidity of his patient, knoAving, as he should, the lasting, pernicious consequences that must result from doing so. If he is not permitted to carry out such plan of treatment as may be necessary to put the mouth of his patient in a healthy condition previously to the application of artificial teeth, he should refuse to render his services. No professional man can be permitted to plead in excuse for any pro- fessional error that his patient over-persuaded him. No community Avill accept such excuse, or hold the patient in any degree responsible *br the consequences. Dr. Koecker, in treating upon this subject, says: " There is, perhaps, 504 PREPARATORY TREATMENT OF THE MOUTH. not one case in a hundred, requiring artificial teeth, in which the other teeth are not more or less diseased, and the gums and alveoli, also, either primarily or secondarily affected. The mechanical and chemi- cal bearing of the artificial teeth, even if well contrived and inserted upon such diseased structures, naturally becomes an additional aggra- vating cause of disease in parts already in a sufficient state of excite- ment; if, hoAvever, they are not well constructed, and are inserted with undue means or force, or held by too great or undue pressure, or by ligatures or other pernicious means for their attachment, the morbid effects are still more aggravated, and a general state of inflammation in the gums and sockets, and particularly in the periosteum, very rapidly follows. The patient, moreover, finds it impossible to preserve the cleanliness of his mouth ; and his natural teeth, as well as the arti- ficial apparatus, in combination with the diseases of the structures, become a source of pain and trouble; and the Avhole mouth is rendered highly offensive and disgusting to the patient himself as Avell as to others." * The first thing, then, claiming the attention of the dentist, Avhen applied to for artificial teeth, is to ascertain the condition of the gums, and of such teeth as may be remaining in the mouth. If either or both are diseased, he should at once institute such treatment as the circumstances of the case may indicate; but as this has been described in a preceding chapter, the reader is referred for directions upon the subject to what is there said. Without, however, repeating previous medical and surgical directions, a few brief hints are necessary as to what teeth or roots should be extracted and what allowed to remain in preparation for a dental plate. All incurably diseased roots or teeth should be removed, also all roots of molars in either jaAV, and all roots, Avithout exception, in the lower jaw. Firm and healthy roots of bicuspids may sometimes be retained, the plate coming to the inner edge of such root and the arti- ficial croAvn resting upon it. It is desirable to retain upper incisors or canine roots, unless an adjacent tooth' has lost its root or is incurably diseased. These cases of retention of roots presuppose the presence of other teeth ; for AA'hen only roots remain in the jaw, they must be extracted. Also, they must be removed, however sound, if they are sources of irritation in, or are partially covered with, mucous membrane. Very loose teeth, although not carious, should be extracted; but teeth in which caries or abscess can be permanently cured rank as sound teeth. All sound teeth must be retained, if there are more than four in either jaw, unless some peculiar circumstances justify their removal. Cases of this kind are so varying that no fixed rule can be laid down ; * Koecker'e Essay on Artificial Teeth, pp. 27, 28. PREPARATORY TREATMENT OF THE MOUTH. 505 but a feAv cases may be given in illustration of the principles that should guide the practitioner. Two, three, or four molars alone remaining should be retained, espe- cially if they have antagonists. They do not complicate the construc- tion of the piece or interfere Avith its utility ; but they should not be clasped, since the Avhole weight being in front of the clasp brings too much strain on the teeth. Two, three, or four incisors alone remain- ing cannot be extracted except by request of the patient; for although they complicate the construction, and may interfere somewhat with the strength and beauty of the work, they may be too valuable to justify their loss. The cuspids must be retained, if sound, not displaced, and free from alveolar absorption, although their retention may greatly complicate the Avork. In cases of protrusion of the lower jaAV, it may be advisable to extract the five front teeth in either jaw, Avhere these are the sole remaining ones, Avith a view to correct, in part, the protrusion of the mouth. But this cannot be done Avithout fullest consent of the patient; even then is scarcely advisable unless these teeth are frail in texture, or their position amounts to deformity. In all cases it should be the rule never to sacrifice a sound tooth for the purpose of replacing an artificial one, unless the benefit of the exchange is so undoubted as to be recognized by both patient and operator. When artificial teeth are to be secured in the mouth in any other Avay than by pivoting upon the roots, if the patient desires but one piece, sufficient time should elapse, before its insertion, for the comple- tion of those changes in the alveolar ridge that folloAv extraction. It is often necessary to wait from eight to fifteen months, after the removal of the natural teeth, for the completion of these changes. Comparatively feAV persons, hoAvever, are Avilling to remain for so long a time Avithout teeth ; nor, on many accounts, is it desirable that they should. In this long interval the lips lose somewhat their natural ex- pression, and the under jaAV forgets its natural motion, and inclines to project. The artificial piece or pieces feel more aAvkAvard and unman- ageable than if inserted at once; they also interfere more Avith the articulation and motions of the tongue, which have become accustomed to the absence of the teeth. Hence the insertion of artificial pieces may become advisable very soon after extraction — the interval varying from hours or days to weeks or months. In some of these cases the piece Avill have to be remodelled at short intervals; in other cases the piece, as first made, continues to be Avorn for many years Avith much comfort. It is not easy to explain these differences. Much depends upon the nature of 506 PREPARATORY TREATMENT OF THE MOUTH. the mucous and submucous tissues, Avhether hard or soft; and much also upon the manner in Avhich the alveolar ridge changes. It may take place rapidly, and with slight regard to the shape of the plate; in Avhich case the patient has to use much tact in retaining the piece in place. Or it may take place slowly, following, as it is apt more or less to do, the shape of the .plate; in which case it may be worn with some comfort, or even Avith great satisfaction, for a long time. A plate made immediately after extraction should not fit the ridge exactly ; but allowance should be made for the rapid absorption of the prominent edges of the alveoli. Some practitioners advise the anticipation of this process by " paring doAvn'" the alveolar ridge. This " bold surgery" has its advantages and its advocates. The opera- tors say it does not hurt much ; but the testimony of the patient, on this point, is more trustAVorthy. The almost universal use of the term "temporary," applied to a piece made within six months after extraction of the teeth, is much to be regretted. It tempts the dentist to a slovenly style of half made Avork, good enough, in his estimation, for what is so soon to be replaced. It also renders the patient reluctant to make proper compensation for the time and skill employed. Both feelings react, until it has become a notorious fact that much low-priced work passes from the hands of skilful mechanicians Avhich they would indignantly disown as specimens of their Avorkmanship. Yet they are specimens Avhich a community is right in judging by. It is unfortunate for dentistry that so many, using their best efforts, accomplish poor results. But it is infinitely more damaging to its character, that a skilled operator should, under any pretext, permit himself to be false to the trust reposed in his professional capacity. A chain is judged by its Aveakest link, and a workman's reputation turns on his poorest Avork. This seemingly harsh verdict is a just one, because necessary to keep the majority of men to the full measure of their ability. Let the work be done as if it never was to be done again. Many circumstances may prevent the return of the patient: it also frequently happens that no necessity is felt, especially if properly done, for the renewal of the piece. If the patient understands that the necessity of renewal is not in the Avork itself, but arises from unavoidable changes in the mouth, there will be no difficulty about proper compensation. But if the absurd practice of half price at one time for Avhat receives full price at another must be maintained, then, by all means, let the second piece be the half-paid one. The point, hoAvever, involves far higher questions than the one of fees. No dentist Avho properly respects himself or his profession, will, PREPARATION OF A NATURAL ROOT, ETC. 5C7 either on the score of insufficient pay or temporary use, permit himself to issue two grades of work. Like Pharaoh's lean kine, the low grade Avill, sloAvly perhaps, but inevitably destroy the high grade. The only safe rule is " excelsior " in every case. CHAPTER V. PREPARATION OF A NATURAL ROOT AND ATTACHMENT OF AN ARTIFICIAL CROWN. PREVIOUS to the preparation of a natural root for the reception of an artificial crown, the remaining teeth and gums, if diseased. should be restored to health. This done, such portion of the crown, as may not have been previously destroyed by caries, should be re- moved. The usual method of performing this part of the operation, when much of the croAvn remains, consists in cutting the tooth about three- fourths off, with a file or very fine saw (Fig. 189), and then removing Fig. 189. it with a pair of excising forceps. But the forceps should not be applied until the tooth has been cut with a file on every side, nearly to the pulp-cavity, and even then great care is necessary to prevent jarring, or otherwise injuring the root. When too large a portion of the crown is clipped off suddenly with excising forceps, the concussion is often so great as to excite inflammation in the socket of the tooth, and some- times to fracture the root. When excising forceps are used in this way, they should be strong, so as not to spring under the pressure of the hand, with cutting edges Fig. 190. about an eighth of an inch wide (Fig. 190). But we should prefer, where a large part of the crown is left, to remove it entirely with the 508 PREPARATION OF A NATURAL ROOT fine saw or separating file. Where there is only a jagged remnant of the crown left, it should be gradually cut aAvay by a pair of cutting forceps made as light as possible, with a spring betAveen the blades of the handle to keep them apart. The cutting edges may be shaped as in the ordinary excising forceps (Fig. 190), or somewhat like the beaks of Parmly's duck-bill root forceps, represented in Fig. 191. After the removal of the remaining portion of the crown, the nerve, if still alive, should be immediately destroyed, by introducing a silver or untempered steel wire, or some other small, sharp-pointed instrument, up to the extremity of the root, by giving it, at the same time, a quick rotary motion. It is important that the instrument used for this pur- pose should be soft and yielding, otherwise any sudden motion of the patient might break it off in the tooth. Its extremity should also be barbed or bent so as to entangle and drag out the nerve Avhen Avith- drawn. Some recommend destroying the nerve by the introduction of a hot wire into the canal of the root, but as this is very liable to produce irritation in the surrounding tissues, the other method is pre- ferable. The nerve having been destroyed, the remainder of the operation will be painless. The root may now be filed off, a little above the free edge of the gum, Avith an oval or half-round file. The file should be new and sharp so as to cut rapidly, but not too coarse, lest it jar the root to much. It must be kept cold and clean by frequently dipping in water. The exposed extremity of the root, after having been thus filed, should present a slightly arched appearance, corresponding with the festooned shape of the anterior margin of the gum. After having completed this part of the operation, the natural canal in the root should be slightly enlarged Avith a burr-drill, or a broach prepared for the purpose. A slightly projecting point on the end of the drill will serve by entering the canal to guide the instrument, which must be held steadily in one direction. The canal thus formed in the root for the pivot should never exceed the sixteenth part of an inch or a line in diameter, and a quarter or three-eighths of an inch in length. If from any peculiar constitutional susceptibility there is reason to apprehend inflammation of the alveolo-dental membrane, the insertion AND ATTACHMENT OF AN ARTIFICIAL CROWN. 509 of the tooth may be delayed a few days for the subsidence of any irri- tation which may have been occasioned by the preparation of the root. It will be prudent to do this in all cases, although it rarely happens that the operation is followed by any unpleasant effects, unless the root has previously lost its vitality by the spontaneous disorganization of the nervous pulp. In this case, an outlet is sometimes made by cutting a groove on the side of the pivot, or in some other Avay, for the escape of any matter which may form at the apex of the root; but it is far better in such cases to extract the root, unless the discharge can be per- manently arrested. Dr. Maynard believes that the irritation in most cases arises from an accumulation of acrid matter in the upper part of the root; by removing which, and by filling the natural canal above the terminus of the pivot, up to the extremity, it may generally be prevented. This should always be done before deciding to extract the root. After having prepared the root, an artificial croAvn, of the right shape, color, and size, is accurately fitted to it. It should touch every part of the filed extremity of the root, and be made to rest firmly upon it, to give security of support, and to exclude food and other substances Avhich by their decay will give rise to unpleasant odors. Care must also be used to have the tooth placed in exact line Avith the other teeth, not inclining unnaturally to either side, and not so long as to touch the lower teeth when the mouth is closed. To fit the crown accurately is often a tedious process, and wearies the patient. To avoid this, an impression of the space may be taken, and the croAvn adapted to the model, Avhich should be hardened by varnish or soluble glass. The canal in the root, and that in the artificial crown, should be directly opposite to each other. When the crown of a natural tooth is used, it can be adapted to the root by the use of the file; the proper place for the pivot is indicated by the pulp-cavity, but in porcelain teeth the hole is not always in the centre. FlG ]p2. In selecting a suitable artificial pivot tooth, it is often difficult to find the several conditions of length, width, color, and po- sition of pivot-hole just as required. The last two cannot be changed, but the first two may often be modified by the corun- dum wheel. If the color cannot be ex- actly matched, it is perhaps better to select one a shade darker rather than lighter. For grinding the edge, sides, or base of the tooth, any of the hand-lathes in 510 PREPARATION OF A NATURAL TOOTH use will answer very Avell. Fig. 192 represents one where the Avheel, either of stone or corundum, revolves in a vessel containing water. Figs. 193 and 194 represent very convenient and useful forms of the hand-lathe. The foot-lathe, elsewhere described, is best suited for the laboratory; but, for such grinding and fitting of teeth as must be done at the operating chair, a hand-lathe will be found very convenient. Fig. 194. The artificial crown may be secured to the root by means of a pivot made of wood or metal; when the latter is employed, gold or platina is to be preferred, inasmuch as silver or any baser metal is liable to be oxidized by the fluids of the mouth. If wood is used, it should be of the best quality of well-seasoned young white hickory, as this possesses greater strength and elasticity than any other that can be produced in this country. After being reduced nearly to the size of the canal in the artificial tooth, it should be forced through a smooth hole, of the proper size, in a piece of ivory, bone, steel, or some other hard sub- stance, for the purpose of compressing its fibres as closely together as possible. Thus prepared, one end is forced into the cavity in the arti- ficial crown, and the projecting part cut off about a quarter or three- eighths of an inch from the tooth, according to the depth of the canal. If the canals in crown and root are equal in size, the pivot is ready to AND ATTACHMENT OF AN ARTIFICIAL CROWN. 511 be pressed into place, which should be done with the thumb and fore- finger, if the pivot is made of compressed wood. But if the canals differ in size, the wood must be compressed to the size of the larger, and then trimmed down to fit the smaller. The end thus trimmed should require more force for its introduction, since the compressed wood swells most from moisture. The part of the pivot going into the root, if made of compressed wood, should never be so large as to require any other pressure than that which can be applied with the thumb and forefinger, as the swelling of the Avood will soon render it sufficiently tight to hold it firmly in its place, and if too tight, the subsequent sAvelling will split the root. The practice of driving a pivot up Avith a hammer, or by very strong pressure, as is often done, is a bad one. It is apt to cause inflammation and suppuration of the soft tissues about the apex of the root. The utmost force admissible, and this only in the case of uncompressed pivot-wood, is someAvhat more than can be made with the thumb and finger, applied by means of a small pine stick, notched at the end to receive the cutting edge of the tooth. It is important that the pivot should exactly equal the depth of the canal. If too long, the crown will not go up to its place ; if too short, there Avill be either an unnecessary weakening of the root or the crown will be insecure. A small piece of smooth wire or knitting-needle, with a sliding collar of wood or gutta-percha, forms a simple instrument for measuring the depth of the canal in the root. Fig. 196 represents a convenient gauge for this purpose. A porcelain tooth Fig. 196. $ with a Avooden pivot presents, before insertion, the appearance repre- sented in Fig. 195. It sometimes becomes necessary to remove the artificial croAvn, and in doing this the pivot often remains in the root. For the extraction of this, the forceps represented in Fig. 197, invented by Dr. W. II. Elliott, will be found very useful. With this instrument the pivot may be removed from the root Avithout jarring it in the least, or ex- erting any extractive force upon it. The manner of applying and using the instrument will be readily understood by examining the dniAving. When a metallic pivot is used, the end going into the artificial croAvn may be fastened in either of the folloAving ways. First, by cutting a screw on it, either with a file or passing it through a screw- 512 PREPARATION OF A NATURAL ROOT plate; the cavity in the crown should next be filled with a wooden tube, and the pivot then screwed into it; or the pivot may be first screwed into a small block of pivot wood, and the wood then trimmed to fit the crown. Second, by filling the pivot-hole with pulverized Fig. 197. borax, moistened with water, inserting the end of the pivot into it, which should be large enough to fill the cavity, placing several small pieces of solder around it, and fusing them with the blow-pipe. The solder, adapting itself, when in a state of fusion, to the rough walls of the cavity in the crown of the tooth, will prevent the pivot from loos- ening or coming out. The projecting part of the pivot should be about half an inch in length. By some it is made square and pointed, as in the figure ; but the best form is a polished cylinder. The latter resists more firmly any downward traction ; while the curve of the face of the root will prevent the pivot turning on its axis. The cavity in the root, which requires to be deeper for a metallic than for a Avood pivot, should Fig 198. De filled with wood, having a small hole through the centre. I __ Into this, the end of the pivot is introduced and forced up, i 111 J untu the tooth and root come firmly together. The appear- f |T ance of a porcelain tooth prepared with a metallic pivot, f for insertion in this manner, is shown in Fig. 198. But when a metallic pivot is used, a plate tooth is preferabk to one made expressly for pivoting. The manner of attaching a pivot to the former is as follows : the root is first prepared, after Avhich an im- pression is taken; from this a plaster model is made, and from the latter metallic dies. This done, a piece of gold plate, large enough AND ATTACHMENT OF AN ARTIFICIAL CROWN. 513 to cover the root, should be SAvaged up between the dies, a plate tooth of the proper size, shape, and color is then fitted to the root, backed with gold, and soldered to the plate. To the upper or convex surface of this last, and immediately be- * neath the canal in the root, a gold pivot is attached. The position and direction of this pivot is thus secured. ,{ Press the plate, covered with a very thin film of wax, §L against the root; at the point opposite the canal, thus marked on the plate, drill a hole; through this pass a gold pivot into the canal; press softened sealing-wax around the part of the pivot (made purposely too long) beloAv the plate, and remove the fixture from the mouth. Invest the upper part of the pin and plate in plaster (keeping it, by means of a minute collar of Avax, out of the hole through which the pin passes), remove the sealing-Avax, cut off the pin even with the plate and solder. A front and side view of a tooth thus prepared is shoAvn in Fig. 199. A pivot, consisting of gold encased in a thin layer of wood, con- stitutes about as secure a means of attachment as can be employed. It is prepared in the folloAving manner. The gold is first made into wire of proper size, and passed through a screw-plate; a hole is then drilled iengthAvise into a piece of well-seasoned hickory, as far as required for the length of the pivot, and a thread cut Avith the corresponding screw- tap ; into this the wire is screAved, and then cut off close to the Avood, which is reduced with a file or knife nearly to the size of the orifice in the artificial croAvn, and then condensed by passing through a pivot draAV-plate. Subsequent manipulations are the same as given for the simple Avooden pivot; from which it differs in being stronger, also in permitting a slight bend in the pivot in case the canals in root and crown are not in precisely the same direction. The Avood prevents the gold from enlarging the cavity of the root, or from being worn by friction in the pivot-hole of the artificial tooth; and at the same time, by the SAvelling of this encasement, the pivot is firmly retained in both. There is some diversity of opinion with regard to the best kind of pivot. Some prefer Avood, others metal. Dr. Fitch, on this subject, observes: "The metallic pivots are far better than any other; their only objection is, that they are apt to wear the tooth that is placed upon them, and the stump in Avhich they are inserted. So much so do thev have this effect that we are induced to use pivots of wood. This last has the advantage, if perfectly seasoned, of SAvelling in the stump by the moisture Avhich they absorb, and, in this Avay, becoming very firm. The advantages and disadvantages of the two kinds are, per- haps, nearly balanced." 33 514 PREPARATION OF A NATURAL ROOT To the use of wood, Dr. Koecker is decidedly opposed. " The pivots should be made only of fine gold or platina; every other metal, such as brass, copper, silver, and even inferior gold, are highly objectionable, being more or less liable to corrode, and thus become injurious to other teeth and the general health. There is, however, a practice which is still more improper, namely, the use of pivots made of wood; these pivots expand considerably after insertion, from the moisture of the mouth, and consequently remain perfectly firm in the roots for several years, which deceives not only the patient but the dentist also, and induces them to consider the case very successful, until they at last find that the root is either split by the swelling of the pivot, or nearly destroyed by the rapid decay of the wood in the cavity, which, by its chemical and mechanical irritation, is very apt to produce serious inflammation, and other affections of the gums and sockets; by no means the least objection is the disagreeable breath which must be an unavoidable concomitant of this practice. I have made it a universal rule to insert the tooth in such a manner that the patient shall be able, after receiving the necessary instructions, to remove it and re- place it at pleasure ; for this purpose I have found it best and most effectual to wind a little cotton round the pivot, which should be somewhat roughened previously to its insertion into the fang." The description here given of the effects supposed to be produced by a wood pivot is exaggerated. If properly made of good wood, it is no more liable to produce irritation, and to affect the breath, than one made of gold or any other metal, and wrapped in cotton. The fact that wooden pivots remain firmly in the roots for several yeara ought rather to be considered as a recommendation than an objection, and would go far toward determining our preference in their favor. The frequent removal and replacement of a pivoted tooth greatly tends to hasten the destruction of the root and to irritate surrounding parts, and prevents the possibility of having a firmly-fitting crown. In fact, we are disposed to regard the wooden pivot, either simple or stiffened by a gold wire, as much the best for a sound root normally placed in the alveolus. As a general rule, not more than tAvo roots should be prepared at one sitting, though sometimes four or even six may be prepared Avith- out incurring any risk. When a tooth is attached by any of the ordinary modes of pivoting, the walls of the canal in the root are, of necessity, exposed to the action of the fluids of the mouth, and, conse- quently, are gradually softened and broken down ; so that, in the course of a few years, a larger pivot will be required, and this, too, will have to be again replaced with one still larger, until, finally, the root is destroyed. This destructive process proceeds more rapidly in AND ATTACHMENT OF AN ARTIFICIAL CROWN. 515 some cases than in others, accordingly as the root is hard or soft, and as the secretions of the mouth are in a healthy or vitiated condition. This may be prevented by introducing a gold cylinder for the reception of the pivot. This protects the walls of the canal against the action of corrosive agents, and a root thus prepared will support an artificial croAvn more than twice as long as when prepared in the ordinary way. The operation, hoAvever, is more tedious and expensive, and only the larger roots will permit the enlarged size of canal required. For the preparation of a tooth in this manner, the following is the method of procedure : First, the croAvn of the natural tooth is removed, the nerve, if alive, destroyed, and the canal in the root enlarged as before directed. Secondly, a screw-tap is introduced for the purpose of cutting a screAV on its inner Avails. Thirdly, a corresponding screw- thread is cut on a piece of hollow gold wire, during which process the gold tube is slipped over a steel mandril to prevent compression. This done, it may be screwed into the root about a quarter of an inch ; the mandril is then Avithdrawn, and the loAver or protruding extremity dressed off, even with the root, with a very fine file. Fourthly, an arti- ficial tooth is selected, of the right size, shape, and color, and fitted to the root; after which a gold pivot is fixed in it in the manner before described, corresponding in size and length to the gold tube in the root. Having proceeded thus far, the operation is completed by applying the tooth to the root, but little pressure being required to force up the pivot. The stability of a tooth secured in this manner, if the pivot be of the proper size, is as great when first inserted as one prepared by any of the other methods, and it may be removed, cleansed, and replaced at the pleasure of the patient." But rnetal against metal inevitably wears, and rapidly so, if removed from time to time. Hence many prefer the Avooden pivot, Avith a wire run through its centre. When the walls of the canal are so much enlarged by decay as to have formed a conical shaped cavity in the lower extremity of the root, the upper end only of the cylindrical screw will take effect. In this case, the space betAveen the lower extremity and the walls of the root must be thor- oughly filled with gold before the Avire on the inside is withdrawn; after which the tube and extruding portions of the gold are filed off even with the root, and polished, before the artificial tooth is applied. The hollow Avire is made by partly folding a narroAv, evenly-cut strip of gold around a steel mandril, (a knitting-needle makes an excellent one,) and passing through a draAV-plate; AvithdraAV the mandril and solder the seam ; then replace the mandril, and complete the drawing until the proper thickness is given. If too thin, it will not hold the screA\r-thread; if too thick, it will either make the canal too small or 516 PREPARATION OF A NATURAL ROOT require too large an opening in the root. Hollow Avire may be pro- cured of the proper size at less expense of time and money than it can be made by a dentist. It is known by jeAvellers as joint wire, because used for the hinges of breast-pins, etc.; but such wire is rarely over twelve carats fine. It sometimes happens that the natural root, instead of occupying its proper position in the jaw, runs very obliquely; so that if the pivot con- necting the artificial tooth to it be straight, the latter will either over- lap the adjoining teeth or else project outward or inward. To obviate this, an angle should be given to the pivot, immediately at the point of junction between the tooth and root. If this obliquity be slight, the wooden pivot, stiffened with wire, can easily be bent to suit; but in cases of greater obliquity, a solid gold pin will be required. Some cases are met with presenting a still more formidable difficulty; as, for example, when the root is situated behind the circle of the other teeth. In a case of this sort, a different kind of tooth and an entirely different course of procedure is necessary. After having prepared the root, an impression of the parts is taken in wax, from Avhich a plas- ter model is obtained,, and from this tAvo metallic dies. With these a gold plate is to be swaged, extending backward so as to cover the root, and forward to form a line with the outer circle of the teeth. To the posterior part of the plate covering the root, and directly beneath the eavity in it, a gold pivot, about three-eighths of an inch long, is sol- dered, and to the anterior part of it a plate tooth of the right size, shape, and shade is attached. A piece of hollow wood, or a hollow gold screw as before described, is now introduced into the root, and into this the gold pivot is inserted. A right superior central incisor, mounted on a plate with a pivot, for insertion in the manner here described, is represented in Figs. 200 and 201. A method of inserting an artificial tooth on a metallic pivot is de- scribed by the late Dr. James B. Bean, in Vol. III., 1869-70, of the American Journal of Dental Science. " Having filed or sawed off the remaining portions of the crown, the exposed surface of the root is smoothly filed to within one-half or one-fourth of a line below the margin of the gum, giving it a slight concave appearance, so as to accommodate the neck of the plate tooth which is to rest against it. It is Avell at this stage of the operation to stop the canal loosely with a pellet of cotton or floss silk saturated with spirits of camphor, and to dismiss the patient for two or three days. If no inflammation be preserft, the canal may then be cleaned out and carefully filled with gold foil from the apex to within four or five lines of the orifice. AND ATTACHMENT OF AN ARTIFICIAL CROWN. 617 "The remaining portion of the canal not filled should now be enlarged to about one line in diameter, if the size of the root will admit of it, down to the gold filling, making the bottom smooth and solid and the sides parallel. The orifice, to the depth of nearly a line, is again enlarged with a burr-drill to about two lines in diameter, and a small groove or undercut is formed around the margin for the retention of the gold filling subsequently to be introduced around the tube. " Hollow gold, jeweller's wire, or simple gold tubes tnadeof gold plate, may be employed. If the latter is chosen, it is formed by bending a piece of ordinary gold plate around a wire, so as to form a cylinder sufficiently large to fit the smaller portion of the canal prepared for it; then solder with the finest gold solder. A pieee of the tube half an inch in length should be cemented with shellac into a hole bored through a piece of Avood half an inch in thickness, to serve for a han- dle ; the interior is then carefully dressed out Avith a jeweller's broach which has a slight taper, making it smooth and regular within. A solid gold wire pivot is now carefully filed and fitted, by grinding it with fine emery and water, making a 'ground joint,' Avhereby the pivot is firmly held when in place. Any portion of the wire that may project beyond the smaller end of the tube should be cut evenly off, while at the larger end it should project at least one-fourth of an inch. "The tube must be taken out of the cement and a piece of plate sol- dered to the smaller end, forming a bottom. An easier flowing solder should be used for this, so as not to disturb the first This tube thus formed, after being cleansed in acid and smoothly filed, is ready to be inserted into the root. "Some have proposed to cut a-screw on the tube, whereby it is firmly secured in its place, and to fill then around Avith gold. But the most convenient Avay is to cut a number of barbs with a sharp knife on the outside looking toward the open end; this retains the gold in place nearly or quite as well as the screw. Being made so as to enter the root rather loosely, several folds of gold foil are Avrapped around it, and after carefully drying the parts Avith bibulous paper — the pivot being in its place in the tube — the whole is forced to the bottom of the cavity, and the loose portions of foil removed. "Having previously prepared some adhesive foil, the space around the tube is perfectly filled with gold. The gold pivot is now removed, and the tube carefully sawed or filed off nearly level Avith the end of the root, and the surface of the gold and the root well polished. "Thus far Ave have the root preserved with a good filling, and a gold tube firmly secured in it containing an accurately fitting gold pivot. "The next operation is to attach a suitable tooth to the pivot, and for this purpose a plain plate tooth is selected that will be suitable in size, 518 PREPARATION OF A NATURAL ROOT shape, and color. This tooth should be so ground and fitted to the anterior edge of the root that the free margin of the gum will cover the point of union. Then after soldering a strong backing to the tooth, it is fitted to its position, with the gold pivot in place, on which has been soldered a small shoulder or ring of plate, and the projecting portion of the wire cut off. This shoulder is to be made in the form of a disk, cut out of gold plate, larger than the diameter of the pivot, then perforated with a hole just large enough to admit the pivot up to the point a little less than the depth of the tube. Being retained at this point, it is made to fit closely down on the root; the Avhole is then care- fully Avithdrawn and bedded up to the ring in plaster and asbestos, thoroughly dried, the wax removed, and the piece soldered with fine solder. If the ring is loose, it must be kept in place by Avax or plaster in the act of withdraAving it from the tube. The pivot is again tried in the mouth, and, if satisfactory, the projecting portion is cut off, smoothly filed, and the tooth attached to it with shellac; then try in the mouth, and alter its position if necessary. If the pivot does not fit too tightly, the whole can be withdrawn together, carefully invested in plaster and asbestos, and strongly soldered. The piece is now finished up, reducing the shoulder around the pivot to less than half a line in breadth ; a large plate covering the end of the root has no advantage, and Avould only form a lodgment for food and the secretions of the mouth, inducing decomposition and the destruction of the root. " If the pivot is not retained sufficiently firm in the tube, it may be wrapped Avith a few fibres of floss silk or cotton, and when forced into its place with a slight rotary motion, it will remain quite firm, and can be used with great satisfaction. If the.adjustments have been properly made, the shoulder or flange will fit closely on the edge of the tube, the neck of the tooth resting on the beveled edge made for it, thereby preventing the tooth from turning on its axis. Proper care and clean- liness, removing the tooth at least three times a week, will enable such a piece to be used Avith satisfaction for many years." Fig. 202 represents an antero-posterior section of a superior central incisor root pivoted in the manner above described, a, dentine of root; b, porcelain tooth; c, pivot surrounded by the tube; d, backing, Avhich is soldered to the tooth and to the pivot; e, filling be- tween the end of tube and apex of the root; /, filling around the tube by wftich it is retained in place; g, flange resting on the edge of the tube; h, junction of the tooth and root, concealed by the margin of gum. Another method for inserting an artificial croAvn on a metallic pivot is that of Dr. T. J. Thomas, by which AND ATTACHMENT OF AN ARTIFICIAL CROWN. 519 the end of the root is protected from the action of deleterious agents, and a firm support given to the tooth. It is thus described by Prof. Gorgas: "Prepare the root as for an ordinary wooden pivot; then select a plate tooth of the proper size, shape, and shade, and fit it by grinding accurately to the prepared root. " After this is done, enlarge the pulp-canal by reaming it out as large as the root will permit; that is, make a conical-shaped cavity in the exposed surface of the root, allowing the margin of this cavity to be quite near to the periphery of the root, with slight undercuts or retaining points on the anterior and posterior walls. " After this cavity is prepared, and that portion of the pulp-canal beyond it filled to the apex of the root with gold, make a square me- tallic pivot of twenty-carat gold alloyed with platinum, in the propor- tion of five parts of gold to one of platinum. This pivot is made in two parts, Avhich are soldered together at the base of the artificial croAvn, and slightly Avedge-shaped. After the pivot is prepared, a thin piece of platinum plate is bent around it, thus forming a square cylin- der into which the pivot perfectly fits. The pivot is then carefully drawn out of the square cylinder, and the edges of this cylinder sol- dered with pure gold. The pivot is again inserted, and the excess of solder and any rough edges which may be found in the cylinder filed off. "After this is done, the cavity in the root is carefully dried and pro- tected from moisture, and the square cylinder, Avith the pivot inside of it, is placed in the centre of this cavity, which is filled around it with gold in as careful and perfect a manner as any crown cavity. The gold is allowed to overlap the margin of the cavity, so as to per- fectly protect all of the exposed — or what, in the ordinary method, Avould be the exposed — surface of the root. "The gold filling, besides protecting the root, retains the square cylinder in the centre of it. In placing the cylinder in the root with the pivot in it, preparatory to inserting the gold filling around it, the split in the pivot should range directly back from the labial to the palatine surfaces, and not transversely. The pivot, after the filling is inserted, is drawn out of the cylinder, which remains firmly fixed in the root, and that part of the cylinder which projects beyond the gold is filed down to a level with the surface of the filling. An impression of this surface is then taken with wax or gutta-percha, and die and counter-die made of fusible metal, by means of which a disk of plati- num plate is swaged to fit accurately the concave surface of the gold filling in the root. " When this is done, the convex surface of the disk is thinly covered with wax, and the disk placed in its proper position over the gold fill- 520 PREPARATION OF A NATURAL ROOT, ETC. ing in the root and slightly pressed on it, in order to obtain an impres- sion of the square orifice of the cylinder, by which a hole correspond- ing in shape and position may be cut in the disk. The outer end of the pivot is then inserted in the square hole made in the disk, secured by means of wax, and the Avhole returned to the root, (with pivot in the cylinder,) in order to make certain that the pivot is in its proper position ; then it is carefully removed and secured by an investment of plaster and asbestos, that the pivot may be soldered to the disk. " The projecting portion of the ph^ot above is filed down to a level with the concave surface of the disk, and the disk and pivot returned to the cylinder in the root, Avhen the plate tooth is placed in position and secured to the disk by means of wax. "This done, the pivot, disk, and the plate tooth are carefully re- moved and invested in plaster and asbestos, in order that a backing of gold may be made, and the tooth soldered to it and the disk. The tooth is now ready to be inserted, and by slightly separating the tAvo parts which form the pivot, at its apex or free extremity, it will tightly fit the cylinder, the two halves acting as springs and pressing against the walls of the square cylinder inserted in the root." In the chapter on vulcanite, the use of that material in attaching an artificial crown to a natural root is described. Prof. Austen, in summing up the merits of pivot-teeth and of the various processes used, concludes: That the old - fashioned plain hickory (or other hard Avood) pivot is the firmest, and, Avhenever appli- cable, the best; that one or both central incisors, if no other deficien- cies call for a plate, are best inserted in this Avay; but that three or more roots in the same mouth (and, of course, in the same jaAV, since loAver teeth should never be pivoted) are better replaced by teeth fitted to the roots, but attached to a plate; in Avhich case a slight projection of the plate (if vulcanite) into the canal would perhaps give greater steadiness to the piece. In reference to metallic pivots and other very ingenious attachments, they require much care, skill, and time; hence are necessarily expensive. He, therefore, does not advise their use in any mouth containing a base-plate for other teeth ; but Avhen the diffi- cult case is the only lost tooth to be replaced, the circumstances may be such as to justify any amount of trouble or expense. It should be remembered that very delicate mechanism is liable to injury under the strong force of mastication; that a metallic pin cannot be as firm in its canal as a wooden one tightened by SAvelling; and that the habitual removal of the tooth necessarily wears and loosens the pin. MANNER OF REFINING GOLD, ETC. 521 CHAPTER VI. MANNER OF REFINING AND ALLOYING GOLD, AND CALCULA- TING ITS FINENESS. GOLD is the best metal and, for general use, the best material, that can be used for the attachment of artificial teeth. When used of proper fineness, it resists the most acrid secretions of the mouth, and undergoes, during long years of use, no change in its strength, form, or texture. Other metals and materials have a special utility, but none have so Avide a range of usefulness, and none can take the place which this royal metal holds in dental prosthetics. Although the manner of refining, alloying, and manufacturing gold into plate, solder, etc., may not, perhaps, be regarded as coming prop- erly within the province of the dentist, yet, as he often experiences great difficulty in procuring them of the right quality, a brief descrip- tion of these several processes is necessary. Especially is this neces- sary, since the dental depots seldom keep on hand any gold plate finer than eighteen carats. This we consider discreditable to the profession which calls for so inferior a quality of metal, rather than to those Avhose business it is to supply their demands. Twenty-carat plate can as readily be kept on hand by manufacturers as twenty-four carat foil. Moreover, some practitioners are so situated that they cannot use gold plate, un- less they knoAV how to prepare it from coin. Gold in its pure state, free from alloy, is too soft and yielding to serve as a suitable support for artificial teeth; but if it contains too much or an improper alloy, it will become tarnished by the secretions of the mouth, rendered too brittle for service, through those molecular changes which take place, with greater or less rapidity, if the plate is less than twenty carats fine. It is, therefore, of the utmost importance that the gold used in connection with artificial teeth should be of the proper fineness, and possessed of the requisite malleability. To secure these qualities, it is necessary to knoAV the kind and quantity of metal with which to alloy it before it is made into plate or other forms necessary for the purposes for which it is to be employed. Gold clippings, filings, and other scraps and parts of old gold pieces, as found in the laboratory, are apt to become mixed with base metals, such as iron from the wearing of files, and, occasionally, small particles of lead, tin, or zinc. If these are melted Avith and permitted to remain in the gold, they will destroy its ductility, and render it unfit for use. 522 GOLD ALLOYS. Iron, less objectionable than the lead or tin, may ahvays be removed Avith a magnet before the gold is melted ; but to free it perfectly from the others, it will sometimes be necessary to refine it in the manner presently to be described. A two-thousandth part of tin or lead de- stroys the ductility of gold, and even exposure to the fumes of red-hot tin or lead renders it exceedingly hard and brittle. Antimony, or bismuth, when mixed with gold, exerts upon it a very similar effect. So marked is the influence of antimony in injuring one of the most valuable properties of gold, that its original name regulus (little king), by Avhich it is best known in commerce, was given in view of this con- trolling effect upon the king of metals. It is of the utmost importance to bear in mind the action of minute quantities of these four metals, so much used in the laboratory, upon gold, platina, and silver. Platina, united Avith gold in certain proportions, has the effect of hardening the latter metal and making it very elastic, but does not materially affect its ductility. The affinity of the alloy for oxygen, hoAvever, is so great, that it is readily acted upon by nitric acid. The acids of the mouth will often make this alloy very brittle. But for this, the tAvo metals, combined in the proportion of fifteen parts of gold to one of platina, would form an exceedingly useful alloy for the construction of spiral springs. That a combination of tAvo metals should be thus easily acted on by an agent incapable of acting on either, when in a separate state, may appear someAvhat remarkable, but it is, neverthe- less, true. We have in the effect of platina upon steel an analogous case. It makes the steel exceedingly hard and fine-grained; but although itself totally insensible to the action of oxygen, when alloyed in minute quantity with steel, it causes this latter metal to oxidize with such readiness as to make it unfit for use. Hence may be seen the fallacy of the idea entertained by many that because platina is a more indestructible metal than silver or copper, it must necessarily make a purer plate. The properties of alloys are, in fact, so often and so widely different from those of their component metals, that they can be ascertained only by experiment. Of the three metals, platina, silver, and copper, speculative theory might select the first and purest as the best alloy for gold; whereas actual experience demonstrates that copper, itself the most injurious to the mouth, im- parts most perfectly to gold, if kept Avithin proper limits, those quali- ties which are required in a dental plate. In vieAV, then, of the importance of having gold, which is to be placed in the mouth, of the right quality, every dentist, Avho has connected with his practice a mechanical laboratory, should have the necessary fixtures for melting and Avorking this metal into the various forms required for dental purposes. The principal of these are, a small REFINING GOLD. 523 furnace, Avith crucibles and tongs, ingot-moulds, an anvil and ham- mers, and a rolling mill; a plate-gauge, draAV-plate, and bench-vice; fluxing and refining chemicals, etc. REFINING GOLD. It is not our intention, in describing the manner of refining gold, to enter into a minute detail of the various methods employed for assaying or refining this metal, but to point out, as briefly as possible, the manner of separating it from the several metals with Avhich it is most frequently combined in the dentist's laboratory. The method usually employed by assayers for separating gold from silver is to roll the alloy out into very thin plates, and put it in nitric acid; this will dissolve most of the silver, and leave the gold behind in the form of brown plates, scales, or poAvder, Avhich after being thoroughly Avashed is put into a crucible Avith borax and melted down into an ingot of pure gold. But this method Avill not succeed, unless the quantity of silver be equal to two or three times that of the gold; for the nitric acid which acts only upon the silver (and copper) cannot eat out all the alloy if its particles are too much surrounded with the particles of gold. From the old rule—one-fourth gold, three-fourths alloy—came the name given to this process, quartation: it is also knoAvn as the nitric acid process. It is well adapted to the purification of gold upon a large scale, and is the process used in the U. S. Mint. But it does not remove the platina so generally found in dentists' scrap; and is not so Avell adapted for gold of eighteen carat fineness and upward as the next process. The nitro-muriatic or aqua-regia process dissoh'cs all the metals of the alloy, but immediately precipitates the silver. The gold is subse- quently precipitated in a state of purity, thoroughly Avashed, dried, and melted down Avith borax. The process is briefly as folloAvs. Melt the scrap to be refined; roll into a thin strip and curl it up into Avhat is technically termed a cornet; place in a porcelain vessel and pour on the aqua-regia, three or four ounces to the ounce of alloy, Avhich must be mixed at the moment of using, in the proportion of one part of pure nitric acid to two, two and a half, or three parts of hydrochloric acid; quicken the solution by heat from a spirit-lamp, setting the vessel Avhere the nitrous fumes can escape from the room ; decant or filter the solu- tion so as to separate the precipitated silver; evaporate the clear solu- tion over a spirit-lamp, nearly to dryness, add hydrochloric acid and evaporate a second time, so as to get rid of all nitric acid. The concentrated orange-colored solution is the chloride of gold to- gether with the chloride of platina and other metals from which it must be separated by precipitation. Dilute largely Avith water, and 524 REFINING GOLD. add little by little a solution of the proto-sulphate of iron (green vit- riol), until the dark olhTe-brown precipitate, which instantly appears, ceases to form. Pour on this precipitate some sulphuric acid to remove all trace of iron, and then wash several times Avith hot water, dry it, and melt with borax in a crucible. If the presence of much platina is suspected, the solution should be treated Avith muriate of ammonia (sal ammoniac) after the gold has been removed. This will precipitate the platina, which should be Avashed, dried, and sold, inasmuch as the dentist has no heat sufficiently intense to melt it. If the alloy to be refined consists simply of gold and platina, the aqua-regia solution, after being made neutral by tAvice evaporating nearly to dryness, should be diluted with water and the platina precipitated by muriate of ammonia; then decant the gold solution from the platina and precipitate the gold by the proto-sulphate of iron. A third method of refining is the sulphuric acid process, Avhich it is unnecessary to describe further than to say that it resembles the quarta- tion process. Gold is melted with five to seven times as much silver, granulated and then boiled three or four hours in a platina or iron retort with sulphuric acid. By any of these three processes, but most conveniently by the sec- ond, dental scrap may be refined to a purity sufficient for every practi- cal purpose. The assayer resorts to other methods to obtain the absolute purity required in analyses. Gold still containing traces of silver may be treated with sulphuret of antimony. This is done with a strong heat in a covered crucible, and after the gold has been kept in a state of fusion for some thirty or forty minutes it should be poured out into an ingotrmould, and sepa- rated from the antimony, which will lie at the top. It may be neces- sary to melt it in this way two or three times, adding, each time, a less quantity of antimony; at the last melting, a current of air, from a pair of bellows, should be thrown upon the surface of the fused metal to evaporate the antimony, and after the vapor ceases to escape, a little refined nitre and borax should be thrown into the crucible. It should then, in a few minutes, be poured into the ingot-mould ; should it crack in hammering or rolling, it must be again melted, and a little more nitre and borax thrown on it. Still another process for refining gold is occasionally used, called cementation. It consists in first rolling the gold out into exceedingly thin plates, then placing it in a crucible with a mixture of four parts of brickdust, one of calcined sulphate of iron, and one of chloride of soda. A bed of this mixture or cementing poAvder is first placed in the bottom of the crucible; the gold is then put in and covered with REFINING GOLD. 525 it. The crucible is covered Avith another crucible, the joints well luted with clay, and gradually raised to a red heat, at Avhich temperature it should be kept from twenty to twenty-four hours. The crucible is then removed from the fire, the top broken off, and after it has cooled, the gold may be separated from the cement and Avashed, or, what is still better, boiled in hot Avater. The form of furnace for melting gold depends much upon the kind of fuel. Charcoal, coke, and anthracite are the three kinds used ; bitu- minous coal is inadmissible until converted into coke. The stove fac- tories now furnish so many convenient forms for the use of any of these fuels that Ave shall not occupy time or space in their detailed descrip- tion. A pipe six feet high will give to the ordinary " preserving fur- nace" a draft sufficient to melt gold with charcoal: coke gives a very intense heat, but needs a stronger draft; anthracite requires a poAverful draft, but gives a more steady heat, needs less frequent renewal, and hence is better for long-continued heats. As regards the shape and size of the stove, the folloAving points should be attended to: convenience of access to the crucible; sufficient depth and width to surround the crucible Avith a good body of fuel, Avithout unnecessary waste of material. Furnaces acting by simple draft will be found to ansAver better than blast furnaces. The Ceylonese goldsmiths use a blast furnace of very rude and sim- ple construction. It consists of a small, Ioav, earthen pot, filled with chaff, or sawdust, on Avhich a little charcoal fire is made, Avhich is excited Avith a small bamboo blow-pipe, about six inches long, the blast being directed through a short earthen pipe or nozzle, the end of Avhich is placed at the bottom of the fire. By this simple contrivance, a most intense heat may be obtained, greater, it is said, than is required for melting gold or silver. For separating iron, copper, tin, lead, or zinc, from gold, the follow- ing simple method may be adopted: after passing a magnet a number of times through the filings or fragments, to remove all traces of iron or steel, put the gold in a clean crucible, covered with another crucible, having a small opening or bole through the top; lute the two together with clay, place them in a bed of charcoal in the furnace, ignite the coal gradually, afterward increase the combustion by means of a cur- rent of air from a pair of bellows or by turning on the draft; after the gold has melted, throw in at intervals of about ten minutes several small lumps of nitrate of potash (saltpetre) and sub-borate of soda (borax), and keep it in a fused state for thirty or forty minutes; then remove the crucible, and plunge in Avater to cool it; break it and sep- arate the lump of gold from the dross; then put into another crucible, melt with a little borax, and pour into an ingot-mould, of the proper 526 REFINING GOLD. size, previously Avarmed and oiled. Bichloride of mercury (corrosive sublimate) is sometimes used instead of or after nitre for the purpose of dissipating the base metals, and often with more certain and better results, especially where the presence of any tin is suspected. If the gold cracks on being hammered or rolled, it should be melted again, and more nitre and borax thrown into it; the inside of the crucible should also be Avell rubbed with borax, before the metal is put in. It is sometimes necessary to repeat this process several times, and if the gold still continues brittle, a little muriate of ammonia (sal ammoniac) may be thrown into the crucible Avhen the gold is in a fused state; after the vapor ceases to escape, the metal should be poured into an ingot- mould, Avarmed and oiled as before directed. This last method of treat- ment Avill make the gold tough, and prevent it from cracking under the hammer, or Avhile being rolled, provided it is, from time to time, prop- erly annealed during the process. By this method of refining gold, knoAvn as the dry process, or " re- , fining by fire," sufficiently accurate results will be obtained for many of the practical purposes of mechanical dentistry ; since the variation of an eighth or a quarter of a carat in the fineness of gold plate is not often a matter of much consequence. Comparing the tAvo classes of refining processes — the humid, by acids, and the dry, by fire — the first is the more accurate, and the only Avay to remove platina or silver; but it is the most troublesome, and requires a familiarity Avith chemical details, which, unfortunately, many dentists are totally ignorant of. The second may remove the lead, tin, zinc, antimony, and bismuth, if in small quantity; and if continued for a sufficient length of time, with a free use of nitre, may remove a large proportion of copper. It can scarcely be depended upon if the object is to make an ingot of pure gold, but will answer admirably if the purpose is merely to lessen the alloy or remove certain impurities. As the dry process is one that the dentist will often have occasion to resort to, Ave shall give (from the seventh volume of the American Journal of Dental Science) the following description of the very ex- cellent method pursued by Dr. Elliot, of Montreal: " The following implements are necessary for this purpose : a small draught furnace, a quantity of fine hard-Avood coal, a clean crucible with a sheet-iron cover (a lump of charcoal is better), a light pair of crucible-tongs, an ingot-mould made of soapstone, a little nitrate of potash, carbonate of potash, borax and oil. The fireplace of the fur- nace should be about ten inches in diameter, and eight or ten deep; this should be connected by means of a pipe with the chimney, so that a powerful draught may be made to pass through the coal. A blast- furnace is objectionable, for the reason that the bellows burns out the MELTING GOLD. 527 coal immediately under the crucible, and it is, therefore, constantly dropping doAvn, Avhich is not the case Avith the draught-furnace; be- sides, the draught-furnace produces a more even fire, a quality equally indispensable. " In preparing for a heat, the furnace should be filled about half full of coal, and after it is Avell ignited, it should be consolidated as much as practicable without choking the draught. The crucible containing the metal and a little borax may then be set on, and more coal placed around and over it, the door of the furnace closed, and the damper opened. It should remain in this way until the gold is perfectly fused. The coal may then be removed from over the crucible, and a bit of nitrate of potash dropped in, in quantity equal to the size of a pea to every ounce of gold, and the crucible immediately covered with a plate of iron. More coal may then be placed over and around the crucible, and the gold kept in a fused state at a high temperature, until the scoria ceases to pass off, which it will do in the course of five or six minutes. The ingot-mould, having been previously warmed, should be placed in a convenient position for pouring, and filled about half full of lamp-oil. The cover should noAV be throAvn off quickly, the crucible seized with the tongs, and at the same instant another small bit of nitrate of potash should be throAvn into it, and the gold rapidly,'but carefully, poured into the mould. " The ingot ahvays cools first at the edges, and shrinks aAvay from the middle. On that account, the mould should be a little concave on the sides, so that the shrinking will not reduce the ingot thinner in the centre than at the edges. " Moulds of the best form will sometimes produce ingots of irregular thickness. Such ingots should be brought to a uniform thickness under the hammer, using the common callipers as a gauge. If this be neglected, the plate will be found imperfect at those points Avhere the ingot Avas thinnest. The plate should be annealed occasionally during the process of hammering and rolling, and should be reduced about one number in thickness each time it passes betAveen the rolls. If any lead, tin, or zinc be mixed with the gold, the nitrate of potash must be used in much larger quantities, and, in that case, it is better to let the button cool in the bottom of the crucible. Then break the crucible, and melt it in a clean one for pouring, using borax and nitrate of potash in very small quantities for the last melting. " In case the subject of assay be in the form of filings or dust, a magnet should be passed through it so as to remove every particle of iron, and then, instead of melting it with borax, it should be melted first with carbonate of potash, and aftenvard with nitrate of potash, in quantities proportioned to the necessities of the case, as before directed. * 528 ALLOYING GOLD. Carbonate of potash is the only flux that will bring all.the small particles of metal into one mass. Without it, a great portion of the gold Avill be found among the scoriae, adhering to the sides of the cru- cible, in the form of small globules. This process of refining answers equally as well for silver as gold." ALLOYING GOLD. Gold, when in an unalloyed or pure state, as before stated, is too soft to be used as a support for artificial teeth ; consequently, it has been found necessary to combine with it some other metal, in order to harden it. Silver and copper are the alloys most frequently employed. Many dentists prefer the former, erroneously supposing that it does not increase the liability of gold to tarnish as much as the latter. But this opinion is sustained neither by facts nor experience. Gold, Avhen alloyed Avith copper, unless reduced altogether too much for dental purposes, will resist the action of acids as effectually as when alloyed Avith silver, and the former renders it much harder than the latter. Besides, it renders the gold susceptible of a higher and more beautiful finish. If, therefore, but one of these metals is used, copper may be regarded as preferable to silver. The gold employed in mechanical dentistry by most practitioners is altogether too impure for the purpose, it being not more than eighteen carats fine, and sometimes it is reduced even to fourteen. When not above these standards of fineness, it is discolored by the buccal secre- tions, imparts a disagreeable taste to the mouth, and becomes brittle after it has been worn for a few years. The plate Avhich is to serve as a basis for artificial teeth should never be reduced below tAventy carats; and as that for the upper jaAV does not require to be more than one-third or one-half as thick as that of the lower, the gold for the latter may be a little finer than that employed for the former, as it is necessary that it should be more malleable. The folloAving standards of fineness may be regarded as the best that can be adopted for gold used in con- nection Avith artificial teeth: plate for the upper jaAV, twenty carats; for the lower, twenty-one ; and for clasps and Avire for spiral springs, eighteen. In reducing perfectly pure or tAventy-four carat gold to these stand- ards, first make an alloy of copper and silver, Avhich may be either in the proportion of copper 4, silver 1, or copper 9, silver 1, according to the qualities required in the plate. The effects of the two metals are in strong contrast, — copper giving hardness and elasticity, and deep- ening the color into a red; silver preserving the softness, and giving a greenish-white shade to the original yellow of the pure gold. Of these alloys take — to twenty-one grains of pure gold, three grains; to twenty ALLOYING GOLD. 529 grains of pure gold, four grains ; and to eighteen grains of pure gold, six grains; to make, respectively, twenty-one, twenty, and eighteen carat gold. In the latter case, the alloy should be used containing most silver, as so large a percentage of copper makes the gold too hard and elastic, and gives it rather too red a color. The gold should be first melted in a clean crucible, and as soon as it has become thoroughly fused, the silver and copper alloy may be thrown in, Avith tAvo or three small lumps of borax. After keeping the whole in a melted state for some five or ten minutes, it should be quickly poured into an ingot-mould of the proper size, previously Avarmed and oiled. If the gold cracks during the process of hammer- ing or rolling, it must be melted again, and a few small pieces of borax, with a little muriate of ammonia, thrown in, and in five or ten min- utes recast into an ingot. When scraps and filings are to be converted into plate, they should first be refined, afterward propterly alloyed. This may also be neces- sary with all gold the quality or fineness of Avhich is not known; but with national coins having a known fixed standard this will not be necessary. When they are above these standards of fineness, the amount of alloy necessary to reduce them to the required fineness may be readily found by calculation. It is often unnecessary to change the fineness of either American (21.6 carat) or English (22 carat) coin; especially when the depth of the plate in upper cases, or the prominence of the ridge in lower, gives additional stiffness to the plate. There are two principles upon which plates are alloyed. The first, and common one, is to add as much alloy as the gold Avill stand ; the second is to add the least possible quantity. The first results in eighteen carat gold, and uses mainly silver, lest the six grains of alloy should make it too brittle. The last results in tAventy or twenty- two carat gold, and uses chiefly, or exclusively, copper; since the least quantity of this gives greatest stiffness. The simple rule is to have the purest plate which the form of the mouth will permit. For shallow mouths, requiring increased stiffness, a twenty-carat plate may be used; but better practice still is to increase the rigidity by greater thickness, or sometimes by doubling some part of the plate. In connection with the alloying of gold, it is proper to make some remarks upon the terms in which the fineness of alloys is expressed, and the means of ascertaining it. Pure gold being taken as the starting-point, it may be expressed by unity (1), or by 24, or by 1000. In the first case, fineness is given in fractions. In the second case, by parts, called carats, Avhich, for con- 34 530 CALCULATION OF FINENESS. venience, may be considered as equivalent to a grain ; thus represent- ing pure gold by 24 grains, or 1 dAvt. In the third case, value is expressed in decimals, and is the most convenient system, although the second is the most customary with jewellers and dentists. The following table, prepared by Prof. Austen, will show the rela- tive value of these three systems in a few of the most usual forms of gold alloy: Fractions. Carats. Decimals. Pure Gold..... 1. 24. 1000. English Coin .... 11 22. 916.6 American Coin .... ? 21.6 900. Dentists' Gold, best . §_ 20. 833.3 " '« good 4 19.2 800. Jewellers' Gold, best 3 18. 750. " " good . 5. 15. 625. " " common . i 12. 500. Commonest Solder 1 3 8. 333.3 The table gives the amount of pure gold; subtracting which from the number at the head of each column will give the amount of alloy. For example: best jeAvellers' gold contains eighteen carats of pure gold and six carats of alloy; or three-fourths pure gold and one-fourth alloy; Or 750 parts pure gold and 250 parts alloy. To know how much alloy is required to reduce gold from one fine- ness to another, Prof. Austen gives the following rule : Divide the lower carat (c) by the difference between the lower carat (c) and the higher (C); divide the weight (W) of the gold by this quotient (c-^-(C—c) ), and it will give the amount of alloy (A) to be added. He also gives the follow- ing table of divisors, which will be found convenient, as saving the necessity of much calculation: Carats. 22. 21. 20. 19. 18. 16. 14. 12. 24. 11. 7. 5. 3.8 3. 2. 1.4 1. '22. 21. 10. 6.3 4.5 2.6 1.7 1.2 21.6 35. 12.5 7.3 5. 2.8 1,8 1.3 20. 19. 9. 4. 2.3 1.5 18. 8. 3.5 2. The first vertical column represents the fineness before alloying; the first horizontal column the fineness after alloying. Example: To reduce a double eagle (weighing 516 grains, and 21.6 carats fine) to 20, 18, and 12 carat plate, divide the weight by 12}, 5, and H; this gives the CALCULATION OF FINENESS. 531 amounts of alloy to be added — for the first, 41.3 grains; for the sec- ond, 103.2 grains; and for the third, 387 grains. When it is required to know the fineness of the plate or solder made from known quantities of gold and alloy, multiply the weight (W) of gold, before alloying, by its carat valuation (C); divide this product (C W) by the weight of the gold after alloying (W + A); the quotient will be the carat-value (c) of the alloyed gold. This and the preceding rules may be also expressed by algebraic for- mulas: (10 A=W-h C—« (2.) c = CW W + A The fineness of any mixture of alloys of knoAvn value may be found by a simple arithmetical rule. Multiply each Aveight by its carat (pure gold being 24), divide the sum of the products by the sum of the weights, and the quotient Avill be the carat-value of the mass. The following formulas may be employed for manufacturing gold plate from pure gold for dental purposes: Nos. 1, 2, and 3 for the base, and No. 4 for clasps: No. 1. Gold Plate 18 carats fine. 18 dwts. . . . pure gold, 4 dwts. . . pure copper, 2 dwts. . . . pure silver. No. 3. Gold Plate 21 carats fine. 21 dwts. . . . pure gold, 2 dwts. . . pure copper, 1 dwt. . . . pure silver. No. 2. Gold Ph tte 20 carats fine. 20 dwts. . . pure gold, 2 dwts. pure copper 2 dwts. . No. 4 . pure silver. Gold Plate 20 carats fine. 20 dwts. . . pure gold, 2 dwts. pure copper, 1 dwt. . . pure silver, 1 dwt. platinum. The folloAving formulas may be employed for manufacturing gold plate from coin gold: No. 1 for the base, and No. 2. for clasps: No. 1. Gold Plate 18 carats fine. 20 dwts. . . . gold coin, 2 dwts. . . pure copper, 2 dwts. . . . pure silver. No. 2. Gold Plate 20 carats fine. 20 dwts. . . . coin gold, pure copper, 8 grs. 10 grs. 20 grs. pure silver, platinum. 532 INGOT-MOULDS. CHAPTER VII. INGOT-MOULDS, ROLLING-MILLS, SOLDER. THE gold, after being refined or alloyed, should then be remelted in a clean crucible, well rubbed on the inside Avith borax, and poured into an ingot-mould (Figs. 203, 204,) of proper length, width, and thickness. Fig. 203. Fig. 204. Ingot-moulds may be of iron, soapstone, or charcoal. The first is perhaps most convenient. The second gives, with the same gold, a tougher ingot; whilst with the last the greatest toughness of metal is obtained, so far as the nature of the ingot-mould can modify it. Pig- iron, from the same furnace, run into iron moulds, may be white and brittle ; or into sand moulds, gray and less brittle; or into charcoal, dark gray and soft. Some such modification of the molecular arrange- ment of gold, due to its manner of cooling, is probably the correct explanation of the fact that a charcoal mould yields, other things being equal, a tougher ingot than iron. The charcoal ingot-mould is easily made. Select a firm-grained piece; saw in half, and make smooth by rubbing the surfaces together. Then make the matrix in one of three ways : either cut the shape required out of one-half with the proper gate; or bend a heavy wire into shape of the ingot and gate and bind it between the surfaces; or saw off a charcoal slab, and after cutting out the shape of the ingot and gate, bind it between the surfaces. Those who have once used a charcoal ingot, Avill seldom use any other. ROLLING-MILLS. 533 After it has become sufficiently cool, it may be placed on an anvil, and its thickness reduced to about an eighth of an inch, Avith a ham- mer weighing from one to one and a half pounds. It should then be Avell annealed by being placed in the furnace, lightly covered with small pieces of charcoal, and heated until it assumes a uniform cherry- red color; or it may be annealed Avith the blow-pipe. It may be neces- sary, during the operation of hammering, to subject it once or twice to this process, to prevent the gold from cracking. If, notAvithstand- ing this precaution, it should crack, it must be again melted, and re- fined with muriate of ammonia. Sudden cooling does not make it brittle. On the contrary, some jeAvellers maintain, that if plunged in alcohol and Avater, it is softer than Avhen slowly cooled. A little sulphuric acid in the Avater will give a bright surface to the plate, by cleansing off the oxide of copper; but this acid pickle is only necessary for removal of the metal of the dies, used in swaging, or of the borax used in soldering; in all other cases we prefer to have the oxide coating. After the gold has been reduced to the thickness just mentioned, and well annealed, it may be placed between the rolls of the mill, previously so adjusted as to be the same distance apart at both ends, and not so near to each other as to require a great effort to force it between them. The rollers, however, should be brought a little nearer to each other every time the plate is passed between them, and during this process they should be kept well oiled, so that there may be as little friction as possible. Many roll the ingot without any previous hammering. In the process of rolling, care must be had to anneal often, and to roll in one direction until sufficient width of plate is Fig. 205. Fig. 206. obtained; then, before cross-rolling, be sure to anneal, else the plate Avill be very apt to crack. 534 ROLLING-MILLS. Rolling-mills for gold are variously constructed. Some are very simple, while others are quite complex, having a great deal of machinery connected with them. The rollers also vary in length, from three to five inches. For the gold plate used by dentists, they need not be more than three or three and a half inches long. Fig. 205 represents a simple form of rolling-mill, without the cog-gearing, as seen in Fig. 206. The latter is a strong but simple mill, and is very well suited to the dental laboratory. The set screAvs at the top are turned with a rod, and must be both moved alike, else the plate will be thicker on one side, and will curve laterally in rolling. Fig. 207 represents a more complicated mill, designed for those who do much or heavy rolling. With such a mill, all the rolling of a laboratory could be done without the aid of an assistant. The thickness of the plate may be determined by a gauge-plate. That which is to serve as a basis for artificial teeth for the upper jaw may be reduced until it fits the gauge at 25, 26, or 27, accord- ing to the quality of the plate and the depth or irregularity of the arch. For the lower jaw, and for backings and clasps, it may range from 21 to 24. When the whole alveolar border and a por- tion of the roof of the mouth is to be covered, it may be a little thinner than when applied only to a small surface; also thinner when the arch is deep or irregular. The purer the gold is, the thicker must be the plate. When very wide clasps, too, are employed, it is not necessary that the gold should be as thick as if required for narrow ones ; and low or wide , backings need not be so thick as 'long or narrow ones. Lower plates, if wired around the edge or doubled over the middle third, may be made of the same thickness as an upper plate. But these are matters which the judgment of the dentist alone can properly deter- mine, and, consequently, no rules can be laid down upon this subject from Avhich it will not sometimes be necessary to deviate. GAUGE-PLATES. 535 Gauge-plates are, unfortunately, not uniform. For many years the most reliable Avere those manufactured by Stubbs. But it is difficult to procure them. At the same time it is very important that some standard should be adopted in the profession. Under these circum- stances we approve the suggestion of Dr. S. S. White, who recommends the gauge-plate given in Fig. 208, which has been adopted by the principal brass manufacturers of this country. It may be necessary some- times to make gold wire for spiral springs or other pur- poses, also hollow-tube wire. A A^ draAV-plate (Fig. 209), strong A^ pliers, and bench-vice (Fig. pOfe 210) are the necessary tools for this purpose. The draw- plate should be of the hardest steel, with the holes diminish- ing very gradually. The pliers should be rough at the end for grasping the Avire, which must be often annealed during the process. Tube-Avire may be obtained from the jewellers, by whom it is known Fig. 209. as joint-wire. But it is seldom over sixteen carats fine. For use in the mouth it should be not less than tAventy carats; but for many purposes, pure gold or platinum tubing is better. It is easily made as follows: Take a small strip of plate one-fourth of an inch wide, one or two 536 SPIRAL SPRINGS. inches long; slightly taper one end; bend it around a mandril or com- mon knitting-needle, and pass into one of the larger holes of the draw- plate. Then with the pliers draw it through, and repeat until the edges of the strip meet. Remove the mandril, and solder the seam with fine gold or else pure gold. Lastly, select a mandril or needle, the size of the required tube, and draw the wire until it has the proper thickness. If the bore is to be smaller than any needle at hand, the last draAving may be done without the mandril. The simplest method' of winding wire into a spiral spring is to secure Fig. 210. it between two blocks of wood, held between the jaws of a small bench- vice, as shown in Fig. 210. The upper end of the wire is then grasped by a hand-vice or sliding-tongs, in connection with a spindle or steel wire the size of a small knitting-needle, six or eight inches in length. The spindle, resting on the blocks of wood, is made to revolve, and by this movement the gold wire is drawn through the blocks and wound firmly and closely round the steel rod. GOLD SOLDER. In making gold solder, the materials employed for the purpose, if not pure, should be refined separately. Unless this is done, it will be difficult, and often impossible, to ascertain their relative purity, which should be known to insure the desired result. The gold is placed in a clean crucible with a little borax, and as soon as it has become per- fectly melted, the silver, and afterward the copper, are added. When all are melted, the alloy may be immediately poured into an ingot- SOLDER. 537 mould, previously warmed and oiled. The process of hammering and rolling the solder is the same as that described for gold plate. In con- sequence of the large amount of alloy in solder, it is sometimes so stiff, and even brittle, as to be with great difficulty rolled ; this diffi- culty is increased by the fact that its low fusibility makes it not very easy to anneal without melting. This is especially the case with sol- ders in which zinc or brass is used. In making solder into the composition of which zinc enters, the other ingredients must be thoroughly melted, then the zinc (or brass) intro- duced at the last moment, rapidly stirred, and the metal poured. A piece of charcoal will be found better for making small quantities of solder than a crucible. The solder employed for uniting the various parts of a piece of dental mechanism should be sufficiently fine to prevent it from being easily acted on by the secretions of the mouth. If pure gold is used, the solder will be of finer quality than if tAventy- two carat gold is used, but Avill not flow quite so readily. But twenty- two carat plate may be used, if its alloy is known, by making due alloAvance for the amount, which is easily calculated by use of preced- ing rules. The folloAving makes a solder sixteen carats fine, and may be used for eighteen or tAventy carat gold plate; it flows very freely. No. 1.—Pure gold ....... 6 dwts. Fine silver ...... 1 " Roset copper . . . . . . 2 " By adding one or tAvo grains of zinc, a solder may be made that will flow at a loAver temperature than that made by recipe No. 1. It Avill also have a finer gold color ; but it is apt to impart to the piece a brassy taste, and for this reason the author rarely uses it. Zinc solders are apt not only to have a brassy taste, but also to become brittle after long use. The folloAving formulas, taken from Dr. Richardson's work on "Me- chanical Dentistry," furnish solders (No. 2) over fifteen carats fine, and (No. 3) eighteen carats fine. No. 2. No. 3. Gold coin . . . .6 dwts. Silver .... 30 grs. Copper . . . . 20 " Brass .... 10 " Gold coin . . .30 parts. Silver ... 4 " Copper . . . . 1 " Brass ... 1 " Other recipes might be added, but the foregoing have been found with us to answer every purpose. More difficulty arises in the use of solders from a wrong method of soldering than from defect in the sol- 538 IMPRESSION CUPS. ders themselves. Almost every dentist will be found to have his favorite recipe, which "invariably flows smoothly." The very fact that so many hundred different solders work so well goes far to prove what we have said. Some will boast of using a solder as fine as the plate. This may be true if, by " fineness," we mean simply carat valuation. But a solder containing two grains of zinc to the dwt. is in no true sense as fine as a plate alloyed with th&t amount of copper; yet both are twenty-tAvo-carat metal. Rules ft* the management of solder, plate, and blow-pipe, in the act of solder/ng, will be hereafter given. CHAPTER VIII. CUPS AND MATERIALS FOR IMPRESSIONS OF THE MOUTH — PLASTER MODELS. IN the construction of a dental substitute, mounted upon a plate or base, it is necessary to obtain an exact model of the parts upon which it is to rest, and to which it is to be attached. For this purpose a perfect impression of these parts must be obtained, involving— First, the choice of a suitable impression cup; secondly, the selection of an impression material. IMPRESSION CUPS Must be of such size and shape as to permit their easy introduction into the mouth; also must they follow, as nearly as possible, the out- line of the surfaces to be copied, allowing a uniform space of one-fourth or one-eighth of an inch for the material. These cups are sometimes called mouth-cups, or wax-holders; but we think the name given, and noAV generally used, is greatly to be preferred. They are of two kinds, metallic and gutta-percha. Metallic cups formerly were made of sheet-tin (Fig. 211), cut into shape and soldered, and were so imperfect that it was very often necessary to swage metallic cups to suit special cases. The depots now supply an excellent assortment of well-shaped Britannia impression cups, of which sixteen will constitute a full set; namely, six sizes for full upper cases (Figs. 212 and 213), and three for full loAver (Fig. 215) ; three sizes for partial upper cases (Fig. 214), (in these IMPRESSION CUPS. 539 the outer rim rises at a right angle) ; and four for partial lower (these cups have a depression (Fig. 216) or a place cut out (Figs. 217, 218) to receive the front teeth). Fig. 219 represents Dr. Franklin's cup for full lower impressions: the slot and upper groove permit secondary pressure of the wax or plaster, after the surplus material is forced up, as it is pressed on the alveolus. Exceptional cases, which no form of purchased cup will suit, may require a SAvaged brass, zinc, copper, or silver cup ; or a cup cast out Fn: i. .. Fig. 215. Fig. 216. Fig. 217. Fig. 218. Fig. 219. of Britannia metal, or other tin alloy. The process of SAvaging will hereafter be described; also, the method of moulding a cup from a pattern of wax. Most of these cases, hoAvever, may be met by bending, 540 IMPRESSION CUPS. hammering, or cutting the ordinary Britannia cup: remembering always that a wise economy never hesitates to sacrifice the cup, to secure excellence of the impression or the saving of time. Without this adaptation of the cup to the form of the alveolar ridge and palate, it is impossible, in certain mouths, to get a good wax or gutta percha impression. Cups similar in shape to the Britannia, but not in so many varieties of size, are also made of hard rubber and porcelain. The first cannot easily, and the latter cannot at all, be modified in shape to suit special cases. The porcelain cups are handsome and clean looking; but they are easily broken, and, Avhen plaster is used, it will sometimes leave the glazed surface and cling to the mouth. We, therefore, prefer the Britannia cup, unless the case requires Prof. Austen's gutta-percha cup. These cups were originally devised to meet a difficulty incident to vulcanite partial pieces. Perfect impressions of dovetailed interdental spaces, and the lingual side of molars and bicuspids, often undercut, are impossible in wax or gutta-percha. Yet Prof. A. regards this as essential to the proper construction of a partial vulcanite set of teeth. They are thus made: Take a wax impression and make a model; in partial cases, brush over the teeth of the model one- or two layers of thin plaster, to fill up all undercuts, and to make the plate fit loosely; saturate the model with water, and mould over it a gutta-percha cup. This last is done, not by using the gutta-percha in sheet, but by first making into a ball; then working it from the palate outAvard, leaving a thick mass in the centre. It should be, on the inside, from one- fourth to one-half of an inch thick, so as to be stiff and unyielding; but on the outside not more than one-eighth or one-sixteenth thick, so as to be slightly elastic and yielding. The whole inside of the cup must be roughened up with a scaler or excavator in such a way that the plaster can take firm hold. In most partial cases, the impression will have to be removed in sections; the inside remaining entire, but the outside and the parts between the teeth coming away separately. In certain cases, it is necessary to partially cut through the cup before putting in the plaster, and usually upon the thick masses of gum which fill the interdental spaces. A cut on the inside, in line with the ridge, gives pliancy to an otherwise rigid cup, and permits its easy removal. When it is desirable to extend the cup around the entire arch, so as to get an exact plaster impression, not only of the gum but of all the remaining teeth, this rim of gutta-percha must be slit at tAvo or three points, to give that pliancy which is a chief merit in this form of cup. These cups have no handle, but are removed by inserting a plugging instrument into a small hole previously made in the back part of the cup where it is thickest. IMPRESSION MATERIALS. 541 IMPRESSION MATERIALS Must possess the following properties: (1.) Plasticity in sufficient degree to copy mucous tissues, avoiding the extremes of softness, which permits them to flow from the cup, and of hardness, which requires excessive pressure. (2.) The property of hardening within a short time, and under conditions not incompatible Avith the mouth. (3.) Absence of expansion or contraction, except in very moderate degree. It may also be added that the materials sbould not be such as in taste, smell, or appearance are calculated to disgust a patient. There are three materials answering to these requirements, and pos- sessing properties as distinctive as the sources whence they are derived. From the Animal kingdom, Beeswax ; from the Vegetable kingdom, Gutta-Percha ; from the Mineral kingdom, Plaster. After their separate description, a brief revieAV of their distinctive properties Avill be given. No one of the three can be dispensed with ; no one should be exclusively used. Beeswax. — Formerly the only material used. It is still the only one fit for certain cases, and is absolutely indispensable. The best wax is from virgin combs, and has a rich golden color. Commercial adulterations with tallow, etc., injure it, and mixture with resin makes it harsh and difficult to manage. Gutta-percha is sometimes incor- porated with it to give hardness in warm weather; bleached or white Avax is also used for the same purpose. A very valuable addition is paraffine. Pure paraffine is very plastic, softening at a low temperature (100°) ; but the folds of soft paraffine have no tendency to reunite, and consequently the mass is full of easily separated flakes or layers. It imparts this property to wax, if in too large proportion ; but its moderate use greatly improves the wax. It causes it to soften at lower heat, makes it more plastic when warm, and harder when cool. The depots furnish wax and its compounds in very pure, neat, and convenient forms; so that there is now little necessity for the dentist to spend the time once demanded to reduce the thick cakes into serviceable shape. It may be well, however, to state briefly hoAV to prepare wax for impressions. Melt and pour into cakes one-quarter of an inch thick; cut into pieces about two inches square; and Avhen nearly cold, roll on a wet board, with a wet wooden roller, to one-half or one-fourth this thickness. This breaks down the crystallization, and reduces it to a form very convenient for softening Avhen wanted for use. It may be softened over a broad flame, or before a fire or stove, or in warm water. In using dry heat, be careful not to melt the surface, or give the peculiar whitish appearance that precedes melting. In using water, have a large quantity, to secure uniformity of temperature, and 542 BEESWAX. keep it at 120°-130° Fahrenheit. Below this it will not yield readily to the gum; above this it becomes adhesive. Some practice is necessary in knowing the proper quantity of wax to use in the cup; the usual mistake is to take too much. Select a cup of proper shape and size; if the arch is a deep one, put some hard Avax or gutta-percha in the centre, to force up the wax at that point. This is much better than to have a hole in the cup through which to make pressure with the finger. Such cups are worse than useless, for it is impossible to make secondary pressure without injury to other parts of the impression; except in case of wax projecting above the cup, outside the ridge. Put the wax in the cup; smooth the surface, which should be a little softer than the body of the wax; then introduce and press against the gums or teeth with a steady, uniform, and moderately strong pressure; also, as nearly as possible, in a direction at right angles to the plane of the alveolar ridge. The wax above the cup is pressed against the gums on each side, so that an exact impression may be obtained of all the depressions and prominences on the outside of the arch. But this must be done with great care, holding the cup firmly and pressing the finger against the cheek or lip, rather than directly upon the wax. It is much better in all cases to have the sides of the cup high enough to give the wax support at all points. For this purpose, it becomes necessary some- times to swage or cast a special cup. Very perfect wax impressions can be taken in such cups. On the removal of the cup and wax from the mouth, the greatest precaution is necessary to prevent injuring or altering the shape of the impression. Holding the handle firmly, it must be draAvn directly dowmvard, in case there are front teeth, in the direction of the axes of these teeth. Impressions of a full upper arch sometimes adhere very tightly. They can generally be loosened by drawing up the cheek and lip on one side or both sides alternately; or by a slight cough, which, acting upon the palate, ad- mits air behind and above the impression. Any violence or twisting motion injures the impression; in wax or gutta-percha such defects cannot be detected until, on completion of the plate, maladjustment creates suspicion of its cause. The wax must be kept in the mouth long enough to cool and harden. A small piece of ice in a napkin, held against the under side of the cup, will rapidly harden it. This simple plan is preferable to the use of double cups, into Avhich a stream of cold water is injected. The latter are not only expensive and trou- blesome to use, but they endanger the accuracy of the impression. All wax impressions, unless for models on Avhich other cups are to be made, should be hardened by artificial cold; it greatly helps to prevent change of shape on withdrawal. If the surplus wax, by contact with GUTTA-PERCHA. 543 the lips or teeth, injures the impression, then, if it is a full case, cut off the surplus, dip into warm water, and introduce the same impression a second time; but if it is a partial case, it must be taken aneAV, for the teeth cannot with any accuracy enter their wax impressions. Gutta-Percha. — This very valuable material will be found useful in taking impressions of the lower jaw and in some partial cases, also fre- quently in full upper cases when the teeth are set on a vulcanite base. The manipulations are different accordingly as we wish to make the gutta-percha adhere to the cup, or wish it to part from the sides of the cup, as it shrinks on cooling. In the first case, soften in water heated to 180°-200° Fahrenheit; dry off the water; hold for a feAV moments over a flame, and press into a warm cup ; keep the fingers wet, to pre- vent the gutta-percha from sticking, but do not let wrater get betAveen it and the cup. In the second case keep the surface of the gum wet, and introduce it into a cold and wet cup. When the cup is filled, place again in water at 180° ; then press it somewhat into shape and intro- duce into the mouth. Pressure must be more gentle than for Avax ; it must be kept longer in the mouth, and ice should be used to cool it. Be very careful, in partial cases where there is much undercut or a dovetail space betAveen teeth, not to make the gutta-percha too hard, else it will be almost impossible to get it out of the mouth. Gutta-percha copies surfaces with all the accuracy of plaster; but, although harder than wax, it is more apt than plaster to change its shape upon withdrawing it from the mouth. Its characteristic pecu- liarity is contraction on cooling ; but this is controlled, when required, by the directions above given for making it adhere to the cup. It is less easily manipulated than wax, and not so generally useful; but its property of contraction admirably adapts it to certain cases in Avhich plates, othenvise accurate, fail because too large and loose. Gutta-percha for impressions is supplied in convenient form by the depots. The native color is dark, and calculated to repel fastidious patients. For this reason, also to give it body, it is incorporated with about its oavii weight of white oxide of zinc, magnesia or chalk, and a pinkish color given by vermilion. Thus prepared, it is less sticky when softened, and becomes harder Avhen cool, than the crude article. Placer— Gypsum, Sulphate of Lime, or Plaster of Paris, consists of 28 parts lime, 40 of sulphuric acid, and 18 of water; the first its minera- logical name, the second its chemical, the third its commercial. A beautiful translucent variety of gypsum is known as alabaster; the transparent crystalline variety is called selenite. That, however, used in agriculture and for calcining is in amorphous masses of a grayish or bluish-white color. When exposed to a heat between 300° and 400° Fahrenheit, most of the water of the gypsum escapes. It is then known 544 PLASTER. as calcined plaster, plaster of Paris, or simply plaster. After being properly calcined and pulverized, if mixed Avith Avater to the consistence of thin batter or cream, it hardens in a few minutes, and acquires great solidity. The plaster has chemically reunited with a portion of the Avater, while another portion is mechanically held in the porous mass, and may be driven off by drying. During the process of consolidation it expands, in consequence of the absorption of the water by the par- ticles of plaster. If the plaster is very fine-grained, this absorption takes place quickly, and the expansion occurs while the plaster is soft. But coarse-grained plaster sets before the particles become thoroughly saturated; hence it continues to expand, more or less, for some time after solidification. There is a great difference in the quality of plas- ter. That used for taking impressions of the mouth (and, in fact, for all dental purposes) should be of the best description, Avell calcined, finely pulverized, and passed through a sieve of bolting-cloth previ- ously to being used. The idea of taking impressions for full sets of teeth Avith plaster originated, we believe, almost simultaneously with Drs. Westcott, Dunning, and Bridges, by Avhom, and the profession generally, it has been regarded as adapted almost exclusively to full impressions. Prof. Austen introduced a method of using it in connec- tion with gutta-percha cups, which makes it, in the hands of a careful manipulator, universally applicable to every case in which a dental appliance is called for. He would, however, by no means recommend such universal application, claiming only that the gutta-percha cup Avill give with plaster a correct impression of partial cases of greatest irregularity, Avhere the use of wax or gutta-percha would be impossible. For plaster impressions in ordinary full cases, upper or lower, select a Britannia cup about one-eighth of an inch larger than the alveolar ridge, and, in case of a deep upper arch, build up with wax, so as to give support to the soft plaster; also supply with wax any deficiency in the size of the cup at the back part or around the outside edge. In exceptional cases, requiring a special cup, a gutta-percha one will be found to be much easier made than a SAvaged or cast metallic cup. If properly shaped, it will fully answer the purpose. The late Dr. Bean's practice was to take a wax impression, make model and dies, and swage a plate; then solder a strip from ridge to ridge to hold a stick, which was to act as a handle in removing the impression. He then heated the plate, and coated the palatine surface with shellac, pressing a lump of raw cotton against the adhesive resin. The cotton fibres caused the plaster to adhere firmly to the plate, thus avoiding the great annoyance when scales of plaster, so thin as in this kind of cup, break off. The process is troublesome, but the results very satisfactory. PLASTER. 545 To take a plaster impression, place the patient in a common chair, and after the cup is introduced, incline the head forward, holding it in place with a gentle but steady pressure upon the centre of the cup. The plaster should be very fine-grained and mixed rather thin, to get rid of air-bubbles. If necessary, a little salt or sulphate of potash should be added to quicken slow-setting plaster. The necessity for salt and quantity to be used should not be left to conjecture; hence the importance of setting aside in a well-closed vessel a quantity of " impres- sion plaster." Also, if the plaster is " sIoav," set aside a large bottle of salt water of the exact strength required to make that plaster set properly. There will in this Avay be no danger of the plaster setting too quickly or too sloAvly. If made to set too rapidly, it hurries the operator and increases the risk of failure; if it sets too sloAvly, both patient and operator become wrearied before it is hard enough to re- move. It should require about three minutes to harden after it is introduced into the mouth, Avhich must be done when it is stiff enough to allow the plaster to be moulded into some shape, and yet soft enough to permit no sharp points or angles on its surface. If softer than this, the slightest pressure forces it out of the cup, to run sometimes out of the mouth, sometimes on the tongue and the fauces. This also is apt to occur if an excess of plaster is used. These unnecessary accidents are well calculated to prejudice patients against plaster and, perhaps, against the operator. The hardness of plaster in the mouth can be ascertained by the Avatch, Avhen the exact time required for setting is knoAvn, or by testing some of the plaster remaining in the boAvl. As soon as it breaks with a sharp fracture, it should be removed. To keep it in much longer than this is apt to give unnecessary pain and difficulty in removal, owing to the absorbing property of the hardened plaster, Avhich causes it to cling with great tenacity to the mucous membrane. Full lower impressions are generally easy to withdraw; but some full upper ones adhere very tenaciously. Raising the cheek on one side or in front, and depressing the cup, will detach most cases. This can be done, in case of plaster, without risk of injuring the shape of the impression. Where there is much undercut, the plaster will break; but it can readily be replaced. Sometimes the action of the cheeks and lips, or of the soft palate, will loosen the impression ; or an instru- ment may be used to press up the palate, and thus cause air to pass in at the back, Avhen it may be easily removed. Complicated modifica- tions of the cup to facilitate removal are of little value, and make an unnecessary multiplicity of apparatus. In partial cases, the outer rim (Avhich for this purpose is made efastic, or else in sections) is first detached, and the central portion then loosened 35 546 PLASTER. by an instrument inserted into the back part of the gutta-percha cup. If there should be many broken, detached fragments, either loose or caught in dovetail spaces between teeth, these must be very carefully removed ; and Avhen the surface moisture has dried off, they must, with the utmost nicety, be replaced in the impression. This is sometimes a tedious and difficult operation ; but it is not trouble misapplied, since it is the only way in which perfect impressions of difficult partial cases can be obtained. Should the detached plaster be from a very irregu- lar surface, its readjustment is made much easier by touching the gutta-percha at that point with a camel's-hair brush dipped in very hot water. The fragments being all adjusted and the outside ones secured by a little resinous cement, should there be much broken sur- face on the inside, it is best to varnish heavily with sandarach, to cement the pieces; otherwise, let the surface be prepared, as in full sets, for preventing the plaster of the model from adhering. Wax and gutta-percha require nothing for this purpose, or, at most, a very thin layer of oil. Plaster impressions may be rendered separ- able : 1, by an alcoholic varnish of sandarach or shellac, or a diluted solution of soluble glass, with a little oil upon the varnished surface when dry; 2, by saturating it with as much oil as it will take up with- out standing upon its surface; 3, by coating the surface with a dilute soap mixture. The varnish is best applied with a small bristle brush ; the oil and soap-water with a camel's-hair brush or a stiff, pointed feather. The varnish must be kept well stopped, or from time to time diluted, so as not to become thick. The soap mixture needs occa- sional reneAval, as the plaster gradually neutralizes its oil and renders it unfit for use. Some dentists take plaster impressions, in certain cases, thus: First, a wax impression, as usual; then enlarge, by pressure or by cutting out, the depressions formed by teeth or a prominent alveolar ridge ; lastly, they pour in a thin layer of plaster, and repeat the impression. Others surround certain teeth with a collar of wax, preparatory to taking a plaster impression. The last is a troublesome method, very apt to fail, from the slipping of the wax collars ; nor has it any superiority over a wax impression, to compensate the trouble. The first is a method of doubtful utility, which must not be confounded with the swaged cups of Dr. Bean, or the gutta-percha cups of Prof. Austen. It is, in fact, little else than a saving of trouble, in the making of special cups, for cases where there is no undercut to cause breaking of the plaster. It is evident that, in cases of hatchet- (or club-) shaped teeth, or dovetail spaces, or under- cut ridge, the plaster vs ill often bed itself in the wax; which wax is changed in shape, in the act of withdrawal, at those very points where CHOICE OF MATERIALS. 547 it is the purpose of this kind of impression to give accuracy. And since the wax is inelastic, it is impossible to restore small, thin por- tions of the broken plaster to their exact place. Hence, we decidedly prefer impressions all wax or all plaster, to this combination of the two, Avhich is not calculated to develop the excellences of either. Prof. Austen thus sums up THE COMPARATIVE VALUE of the three impression materials—wax, gutta-percha, plaster — which can only be determined by a careful study of (1) their distinctive peculiarities; (2) the special requirements of different mouths; (3) the kind of base-plate, and manner of its construction. The exclusive use of one is as reprehensible as the indiscriminate use of all. No one is best; nor can any be dispensed Avith. Disregard of this most important fact is a fruitful source of failure in impressions — failures arising neither from defect in the material nor lack of skilful manipulation in the operator, but from want of philosophical selection of resources. (1.) Wax demands strong pressure, and is inelastic; also, it neither expands nor contracts on cooling. It copies a hard gum accurately, although it never gives the fine tracery of gutta-percha or plaster. It also copies a soft gum ; but not until the gum is either compressed or thrown out of shape by the strong pressure required. — Gutta-Percha requires moderate pressure; is slightly elastic: also has, as its marked peculiarity, very decided contraction on cooling, Avhich, however, is under control, as previously explained. Slight undercuts it will take, without dragging, as Avax does; but, on the other hand, it will occa- sionally pass into very narrow interdental spaces and injure the impres- sion in the effort to Avithdraw therefrom. —Plaster permits only gentle pressure, taking impressions of softest tissues in natural position. It slightly expands in setting ; but, in a rigid cup, this makes no ap- preciable, increase in the size of the model. It sets so hard that it will break before leaAring the smallest undercut; but, by virtue of the same quality, it can be used in the most marked cases of dovetail, or alveolar undercut, (2.) Alveolar and palatine surfaces, and their investing membranes, , have a great variety of conditions. These must be carefully examined with reference to the properties, just named, of the impression materials. We have large or small arches; deep or flat ones; irregular or smooth ridges. The mucous surfaces may be uniformly hard or soft; the ridge hard and palate soft, or the more difficult combination of soft ridge and hard palate; or the ridge may be irregularly hard and soft. No one material can possibly be equal to these varying conditions. 548 CHOICE OF MATERIALS. (3.) The mode of constructing the plate will often determine the choice of an impression material. A plate SAvaged upon a zinc die is smaller by the shrinkage of the die. Here—apart from shape or hardness of the parts—plaster would be best, wax next, gutta-percha the worst. A vulcanite plate is larger than the mouth, by the expan- sion of the model. Here, the contraction of gutta-percha will often prove a very valuable compensation ; also the compression of tissue, made by the pressure of wax,—special considerations must determine which of these to choose; but, as a rule, plaster is not best for full vul- canite sets. On the other hand, plaster is best for all partial vulcanite work, and is the only material in difficult cases worthy of any reliance. It may safely be asserted, that the operator who cannot take an accu- rate plaster impression of any partial case, however difficult, has a very imperfect idea of the value of hard rubber. For the majority of partial cases, where SAvaged work is used, wax will give ample accuracy. Where, however, the undercut, and consequent dragging of wax, is very great, plaster must be employed. Large, or hard, or irregular mouths are best copied in plaster; great deviations from normal size, or shape, requiring special cups. A gum of medium softness, bnt uniform, may be taken equally well in any material. This class of mouths have a wonderful adaptation to any thing: variations in size or form must determine the selection of the material. A gum of extreme softness, yet uniform, will give better results sometimes with one material, sometimes with another. It is often very difficult to determine beforehand ; but, in case of failure, let the second impression be taken always Avith a different material. This is especially true of lower sets, where the gum behind is soft and flexible: it is hard to say whether the pressure of wax or the softness of plaster leaves the ridge in best condition; gutta-percha is often very useful in these cases. Irregularity of texture in the mu- cous tissues is a fruitful source of trouble. A hard ridge, with a soft palatine surface, is easily fitted, and any impression material may be used. But the reverse condition will often require the firm pressure of wax upon the ridge; also in all cases of inequal- ity of texture in the ridge itself. As a rule, subject to exceptions, wax is the best for these mouths, and occasionally (especially for vulcanite) the contrac- tion of gutta-percha is useful. The MODELS. 549 old-fashioned shape of upper plates (Fig. 220) will often give the best adhesion and most useful plates, when the central palate is very hard. It is firmer than a vacuiffn cavity, and much more agree- able to the patient. Of course, it must be made of thick plate, to give requisite strength ; doubling the plate, as far as the bicuspids, may suffice. It is evident that an enumeration of all the complications, which call for exercise of judgment in the selection of impression materials, is impossible. By suggesting a few varieties, we hope to direct attention to a much neglected point, in our judgment of utmost importance. Routine practice, Avhich inquires into the reason of nothing, and the one-idea system, Avith its "practice makes perfect" motto, are equally at fault. The future may reveal some new material; but the three Ave now have are alike important and indispensable. MODELS. The model is made of calcined plaster, mixed with water so as to have the consistence of cream; too much water making the model fragile, whilst too little will prevent the escape of the air contained in the plaster, and the model will be porous. This last condition also greatly endangers the full floAving of the plaster into the inequalities of the impression. The model, for convenience of description, is said to have a face, back, body, and sides — terms scarcely requiring explanation. The face, corresponding with the mouth to be fitted, requires greatest care; and the same directions ansAver for it in all models. The body of the model has different shape and size according to the use to be made of it. The back should be, in all cases, parallel Avith the face. The sides are to be either vertical or slanting, according to its uses. In making models, we require a plaster table, with a rim to prevent scattering of Avaste plaster; having at least tAvo drawers in front, a shelf at the back, also an opening for escape of Avaste plaster into a refuse box; a tight plaster can and a bucket of water will complete the outfit of the table. The implements are tAvo or three strong bowls, a plaster scoop, a spatula, an iron spoon, a plaster knife, a scraper, a sponge, and some camel's-hair brushes or Aving-feathers of poultry. Sometimes a marble slab or slate is used for shaping the back of the model upon; but if the table is kept clean and smooth with the scraper, this is not essential; since, in any case, a piece of wet paper should be laid down, to permit the ready removal of the model, for the purpose of shaping, whilst yet rather soft. Running water and waste pipes are apt to become more a nuisance than an advantage to a plaster table; because the latter are so apt to become closed by 550 MODELS. the careless use of plaster. A bucket of water, changed daily, is equally good, and has the merits of simplicity and universal applica- bility. The most troublesome models are the thick ones for sand moulding. The surface of the impression being prepared as above directed, the cup is surrounded with a rim of Avax, waxed cloth, sheet lead, or tin foil, fitting closely to prevent escape of plaster, and about two inches deep. The rims should be slightly curved, to give, when placed around the cup, the requisite flare. Models made in such rims need trimming with the knife. To avoid this, and also to give greatest possible smoothness and regularity to the sides, flaring rings of sheet tin may be used as follows. Set the impression level on the table, and surround with some soft plastic material (wet newspaper made into a pulpy mass is perhaps the most convenient), and into this set a ring of such size as will give a proper shoulder to the model. Fig. 221 Fig. 221. shoAVS such a ring arranged for making such a cheoplastic model. For a sand model, the ring should flare, should conform more to the shape of the cup, and be smaller. For the dipping process of making counter-dies and dies, the model needs no specially nice trimming. For the fusible-metal process, the model should be cylindrical, and not flaring. These are the three forms of thick or deep model. The shallow models are usually made without rims. The impression is filled, then turned down, Avhen the plaster has set sufficiently to permit it, on the remaining plaster, and poured on a strip of wet paper. MODELS. 551 Whilst plastic, it is shaped with the spatula. If for vulcanite or other plastic work, it is taken up while soft enough to dress with the sponge. But if the shallow model is to be used in sand moulding, or in Dr. Gunning's process, it is allowed to harden, and is then trimmed with the knife. In vulcanite models it will save time, and insure greater accuracy in articulation, to extend the model at once and make the articulating portion; as will be fully explained Avhen describing the process of articulation. The sides of vulcanite models need no shaping, except such as neatness and convenience in handling require; since they are subsequently set into the flask ; but they should be no larger or thicker than strength requires. When rims are used, the impression should rest upon the plaster table; if set level, the back will necessarily be parallel Avith the face, since the thin plaster poured into the rim finds its level. In making shallow models, the impression is held in the hand, thus permitting the floAV of the plaster to be aided by moving or tapping it. As before stated, wax and gutta-percha need no oiling; plaster may be oiled or soaped, or else varnished and oiled; it must also be saturated with water just before pouring the model. Calcined plaster for models should not set too rapidly, as this will cause haste, with its attendant dangers. Coarse plaster makes a stronger model, but it has greater expansion. Gum-Avater, or size, retards the setting, but makes the model very hard; salt quickens the setting, but should not be used for any models Avhich are to be kept as per- manent records of the case. It is best to add the plaster to the .water, than the reverse; it makes smoother Avork by permitting the escape of the air; it also, by the amount of unsaturated water, permits the operator to gauge the stiffness of the batter. Yet practised operators may Avith equal success add Avater to the plaster. In all cases the face of the model is the part first made. The thin, freshly mixed plaster is first to be carefully run into the depressions of the teeth or their ridges. A brush or feather is necessary when the cup is stationary; when in the hand, motion or tapping will cause the plaster to flow as desired. Perhaps the surest way to prevent defects on the face, from confined air, is to have a little surplus water in the cup. The plaster (Avhich in this case must not be too thin) settles at once into the smallest crevice under the water, and, if not stirred, it will not be made thin and rotten by it. The impression once filled, the formation of the body is easy. For deep models,, the remaining plaster should be poured at once, that, while thin, it may form a smooth and level back. For shallow models the plaster must slightly stiffen, lest the weight of the impression should make it settle too much into the plaster on the table. The sponge 552 MODELS. is very useful in dressing up a model: it cuts more or less according to the state of the plaster. It may be used to trim vulcanite models directly after the spatula, or to give finish to other models after the use of the knife. But when plaster is fully hardened it has no effect. Figs. 222 and 223 represent upper and lower models suitable for Fig. 222. Fig. 223. sand moulding; the same may be used for dipping. Fig. 224 repre- sents a shallow model in the moulding-flask, show- Fig. 224 . ing how the body of the die is formed by the zinc- half of the flask. The same figure may be taken to represent the position of the thin model at the bottom of an iron cup, in the process of making the counter-die by Dr. Gunning's method. \\j /''?'}■,/ Difficulties arising from undercuts, on the outside of the upper ridge and on the inside of the lower, may be overcome : (1) by filling up the undercut with wax or plaster in all places where it is unnecessary or impracticable to carry the metallic plate; (2) by using a peculiarly constructed flask for mould- ing, such as the one invented by Dr. G. E. HaAves (Figs. 230, 231); (3) by filling the undercut with movable pieces of plaster, technically knoAvn as "false cores." They should be shaped so as to admit of being drawn from the sand; at the same time they must have a decided angle, so as to mark distinctly the place in the sand for their replace- ment. A small nail or tack in the sand, above the core, will keep it in place Avhilst the metal is being poured. (4) By making a sec- tional model (Fig. 225), as suggested by Dr. A. Westcott. It may be made by filling the central third of the wax impression with the plaster, keeping it from the lateral thirds by a temporary use of clay or putty. This is removed and trimmed, leaving the back wider than the face (Fig. 225) ; then replaced in the impression, and filled up on each side with plaster; the model is then removed, properly trimmed, and varnished. MODELS. 553 Dr. Bean's method of making a model in two parts (for his Alu- minum Process) is equally applicable to making models in three parts, Fig. 225. and is perhaps better than the foregoing. He thus describes it.. " To secure a division in the model itself, the best plan is to set up in the impression a septum of thin sheet lead, forming a vertical plane in the median line of the palate, and fitted somewhat to the inequalities of the impression. This plate should have two or three small projections struck up on one side, by means of a small conical punch, and the opposite side has some cotton fibre attached with shellac, in the manner described for preparing impression cups. Fig. 226 represents the shape of this plate (one-half the size), and shoAvs the side on which are the projections. Its proper position will be readily understood when applied to an impres- sion of one of those deep palates now under considera- tion. The side having the projections is oiled, the cotton on the other side wet with water, and while filling up the impression, this plate is set up in the middle, along the median line, so that when the model is trimmed to proper size and shape, it may be carefully broken apart and placed together again, in the same position." Much time may be wasted in the effort to overcome difficulties of undercut in sand moulding. The dexterous removal of shallow models will suffice for most cases of front undercut; and of all others, it may be said that no undercut, on the die, is of any service into Avhich the plate cannot be swaged, or in removal from Avhich the plate is apt to be bent. Removing the impression is a fruitful source of vexation, because 554 MODELS. of the frequent breaking of prominent parts of the model, and other annoying accidents. But these are in every case the result of haste, carelessness, or forgetfulness. First, the model must have time to harden; then the impression, if of wax or gutta-percha, must be thoroughly softened. The common practice of setting the model on the stove is bad; the smell of burning wax is often the first warning of a softening Avhich has gone too far, injuring the model by the ab- sorption of melted wax. It is far better to place it in water at 140° and 150° Fahrenheit, leaving it long enough for the entire mass of Avax to soften : at this temperature the wax does not melt, yet is so soft that it cannot injure the most delicate point of the model. If over 150°, some portions may adhere to the model, and give trouble in removing. Gutta-percha impressions must be thoroughly softened in Avater at 200°; if over this temperature, portions of gutta-percha are apt to adhere to the surface. In partial cases, it is a good plan to first remove the cup, then turn up the edges of softened wax or gutta-percha, till it is free from the teeth, and then remove the entire mass. Plaster impressions require a different treatment. If the cup is wholly or partly of wax or gutta-percha, these must first be softened and removed: a Britannia cup is loosened by light strokes of the plaster knife handle. The impression is then broken away piecemeal. Dipping in hot water makes it rotten, and facilitates, at times, its re- moval. It is often necessary to cut nearly through the impression in places; in doing which, the knife, or graver, must be held so as to guard against injury to the model beneath. Another safeguard is to coat the impression, before pouring, with oil colored by alkanet; or, better still, to tinge the plaster with Avhich the impression is taken with vermilion or Brandon red; it gives the dry plaster a faint pinkish tinge; does not, in this small proportion, injure its setting qualities; and it makes a very distinct contrast with the pure Avhite of the model. FeAV impressions can be used twice; those taken in wax or gutta- percha cups never. Partial impressions of all kinds are necessarily sacrificed to the integrity of the first model. But plaster impressions, in a smooth Britannia cup, may, with proper care, be replaced in the cup, and used again so as to give a model quite equal to the first. Some of these will come from the model entire; but often it is neces- sary to cut a groove over the alveolus, and break off the outer rim in two or three sections. Models are mostly trimmed before removing the impression; but it is always necessary afterward to trim the shoulder. Usually this is done by merely taking off the rough edges, following the outline of the edge of the impression; but for striking up a plate with the outer edge turned up, a flange, or shoulder, about the fourth of an inch wide, MODELS. 555 is formed around the outside of the plaster model, where it is designed that the edge of the base-plate shall terminate on the alveolar border. It may be shaped either in wax or plaster, and should stand off from the ridge at an angle of about 90° or 100', the angle of the rim being completed with pliers after savaging. A plate swaged with such a rim is used in mounting gum or block teeth and in continuous gum work ; it is stronger than a simple plate, and is susceptible of a more beautiful finish. For a lower set of block teeth, the edge of the plate may also be turned up all the way round. An objection to a swaged rim is the occasional difficulty of determining just how far over the ridge the plate should extend ; for any change is impossible, Avithout destroy- ing the rim. Hence the more common practice, except in continuous- gum work, is to solder a gold band or wire, after adaptation of the plate to the mouth, as hereafter explained. The model, if it is to be used in sand moulding, should have several coats of shellac or sandarach varnish applied with a small bristle brush, to give it a smooth, hard, and polished surface. This will pro- tect it from injury by use, render it more pleasant to handle, and cause the sand to part easily from it. The gum-shellac varnish may be pre- pared by dissolving five ounces of shellac in one quart of alcohol. In using this varnish on a damp impression, be careful not to apply a second coat until the first is hard; else it will cause the first to peel, and injure the smoothness of the surface. Sandarach varnish is pre- ferable to shellac, as it is harder; it is also more transparent, and, consequently, does not color the plaster. It may be made in the fol- lowing manner: Take six ounces of gum-sandarach, one ounce of elemi, digest in one quart of alcohol, moderately Avarm, until dissolved; or the sandarach alone may be used. This is, perhaps, as good a varnish as can be used for plaster models. It is easily prepared : but the alcohol should be warmed in a sand-bath or hot Avater, to prevent it from taking fire. To make the finest varnish, the sandarach should be of best quality, and Avashed in Avater before being put into the alcohol. Some, however, prefer a coating of charcoal dust or plumbago for sand models. Models for dipping, or pouring, or the fusible-metal process, should have no kind of varnish upon them. Vulcanite and other plastic-work models may have a protecting coat of dilute soluble glass (nine parts water to one part of the glacial syrup) ; but if too much or too strong a solution is used, it will do more harm than good. 556 DIES AND COUNTER-DIES. CHAPTER IX. DIES AND COUNTER-DIES — SWAGING PLATES. VARIOUS methods have been adopted for procuring metallic dies and counter-dies. The three following are all which the author deems it necessary to describe. The first of these consists in pouring melted metal into a mould or matrix, made in sand with the plaster model: by this means the die is formed, and the counter-die is obtained by pouring metal upon it. The second consists in making the counter- die first, either by immersing the plaster model in metal, or pouring metal upon it; the die is formed by pouring metal into this. The third consists in pouring the metal, for the metallic die, directly into the impression. A very ingenious set of flasks for this purpose, the invention of Dr. F. Y. Clark, of Savannah, can be had at the dental depots. The same may be done, less conveniently perhaps, with the usual Britannia cups and moulding-rings. Take a piece of copper or brass gauze, and fit into the cup before taking the impression. Set the impression, thus strengthened, into a batter (asbestos or sand three parts, plaster one part), poured into a narroAv iron ring (sheet iron will answer) ; carefully work the batter around the edges of the impression, then place upon it the zinc-half of Bailey's flask (Fig. 227). If the impression is thoroughly dried, the first metallic die will be perfect, no matter hoAV much undercut there may be. A second or third may then be taken, more or less defective, but very useful for the first stages of the SAvaging process. Zinc is the metal used by Dr. Clark for the die. In this process the impression may be plaster, or plaster and felspar; but the investing batter should have only enough plaster to bind the asbestos or sand together. Dr. Clark uses a copper impression cup, which Prof. Austen's process dispenses with. The flask and impression must be perfectly dry, and heated nearly or quite up to the fusion- point of the metal used. The second method admits of three modifications: 1. The fusible metal process; in which the model is surrounded Avith thick paper, and fusible metal in a semifluid state is dashed over it with a spoon, the model being cold, so as to rapidly chill the metal. While still Avarm, the paper is removed, and the counter-die trimmed with a knife; for at DIES AND COUNTER-DIES. 557 this temperature it can be cut as readily as cheese. The counter-die, Avhen cold, is then smoked or coated Avith Avhiting, surrounded with paper, and semifluid fusible metal dashed on it, to make the die. This process is repeated, until from two to six dies are made, according to the irregularity of the case. The model should be made in a ring of nearly circular shape and cylindrical; it should also be at least a half inch larger than the alveolar ridge, that the counter-die may have sufficient metal to force up the plate. 2. The dipping process consists in pouring melted lead, type-metal, or peAVter into a sheet- or cast-iron cup or box, three and a half or four inches in diameter, and three or four inches deep, until it is more than half full; then, stirring the fluid mass with gradually in- creasing rapidity until it begins to granulate, quickly brush off the surface dross, and at once immerse the plaster model more or less deeply, as the palate is a deep or shallow one, and hold it there until the metal congeals. To prevent accident from air confined in the palatine arch, a small hole should be drilled through the plaster model. It is then removed, and the whole upper surface of the counter-die covered Avith a thin coating of Avhiting or lamp-smoke as before directed. After this has become perfectly dry, melted block tin, type-metal, or soft solder, at a temperature so low that it will not char, or even discolor Avhite paper, is poured in, until the cup is filled. If the counter-die is so deep that the die has not sufficient thickness, it may be deepened by placing on the freshly-poured metal the zinc half of a Bailey flask, and continu- ing to pour; the metal in the two flasks will unite and form one die. When cold, the castings are removed from the iron cup, separated, and are then ready for use. 3. Dr. Gunning's method, called also the "pouring process," in which a very thin model (made of plaster tAvo parts, and sand or felspar one part) is placed in the bottom of an iron box, three and a half to four inches in diameter, and about two inches deep. It is fastened there by a thin layer of plaster and sand, then thoroughly dried by, gradually raising box and all to the temperature of the melted metal, which is next poured in, and the box set in a shallow vessel of water to cool it rapidly from the outside. To delay the cooling in the centre until the last moment, and so prevent contraction at that place, a very hot pointed iron, someAvhat similar in shape and size to a tinner's soldering-iron, is placed upon the centre of the model before the metal is poured. When cold, this is removed, and the conical space filled with metal. The counter-die is thus made of lead, alloyed with tin or type-metal. The die is made by placing over this a stout wrought- iron ring, and pouring in fusible metal. Dr. Gunning uses from three to eight dies, according to the sharpness of the prominences of the 5-58 DIES AND COUNTER-DIES. model. The method gives, in his hands, very accurately fitting plates. When metallic dies are to be obtained by the first method, mould- ing-flasks and sand are required. Flasks may be of wood or iron. The moulding-box of Avood should be about six inches square. This is to be filled with fine sand, such as is used by brass founders, in the following manner: The deep or shallow plaster model is placed on the moulding-table exactly in the centre of the box, Avith its face upAvard. Sand is then firmly packed around the sides of the model. Sand should then be sifted', covering the face of the model, to the depth of a half inch, the box then filled, and the whole rammed with a firmness proportioned to the coarseness or dryness of the sand — . damp or very fine or strong (i. e. with large percentage of clay) sand not permitting so much compression as sand possessing the opposite qualities, because it would become too compact to permit the escape of the vapors formed during the process of pouring. But the finest sand, rich in clay and quite moist, may be used, if it is dried before pouring. The box is then turned over and gently tapped several times with some light instrument or hammer, for the purpose of starting or detaching it a little from the matrix, and then carefully removed. Great care is necessary that this tapping does not depress first one side and then the other; this would make the die too deep in the centre, and perhaps cause the plate to rock. The model may be loosened laterally, by holding an excavator firmly upon the centie of the die and tapping it on the side. If the model be composed of three pieces, the middle section is first removed, and afterAvard the tAvo others. There are two ways of drawing the model: first, by screwing into it an excavator or gimlet, and carefully drawing it out; second, by throwing it out with a dexterous jerk of the matrix. The Fig. 228. Fig. 228 represents the two ends of a double spatula, which will be found very useful in sand moulding. DIES AND COUNTER-DIES. 559 last is best; the excavator is apt to break through the centre of the thin model, and the thick one falls out, by its own weight, better than it can be draAvn. If the deep model is used, the matrix is now ready for pouring; but first remove all loose sand, and make a groove at the back part of the matrix to receive the first flow of the metal. If the thin model is used, a ring must be set upon the sand after the model is draAvn, to give the additional size which the die requires to prevent cracking under the sAvaging-hammer. The mould being prepared, the metal to be employed for the casting should be put into a tolerably thick wrought- or cast-iron ladle, and melted in a common fire or furnace. If brass is used, the latter will be required to melt it: but if zinc, block tin, or lead, a common fire will afford sufficient heat. As soon as the metal has become thoroughly melted, it is poured into the furrow formed in the sand, AA'hence it will flow into the back part of the mould. It is necessary to convey the melted metal into the mould in this way to prevent the injury which the surface of the sand might sustain by pouring directly upon it. There have been quite a number of moulding-flasks devised to super- sede the wooden one just described, or the common cart-wheel box, Avhich Avas once much used. Some of these are worse than useless ; others are very convenient, and have the advantage of requiring only a small quantity of sand ; also of permitting the sand to be dried, Avhich cannot be Avell done in the Avooden box. The simplest, and perhaps best, flask is that invented by Dr. E. N. Bailey. Fig. 229 represents the shape and Avorking of this flask. Fig. 229. Half-flask B is placed, joint edge doAvnward, over a thin model, and firmly packed with sand. It is then turned; the sand compressed around the edge of the model; then trimmed so that the model may be easily draAvn (a properly shaped model renders much sand trimming unnecessary); the model is then lightly tapped and throAvn out. All operations on the thin model must be conducted Avith great care, for it is easily displaced in its matrix, so as to destroy the accuracy of the latter. Next, pour zinc into the mould, and at once place on half- flask A, and complete the pouring. When cool, remove the sand, in- 560 DIES AND COUNTER-DIES. vert the flask, with zinc die contained, and pour the lead (C) upon the zinc for the counter-die. In cases of moderate undercut in front, the thin model can gener- ally be drawn by a dexterous backAvard movement. But for a deeper undercut in front, also for those at the side, the moulding-flask of Dr. Hawes (Figs. 230, 231, 232) will be found useful. The manner of using it is thus described by Dr. C. C. Allen: " If the model be considerably smaller than the space between the flanges projecting inward, small slips of paper may be placed in the joint, extending to the sides of the model, so as to part the sand when opening the flask for the removal of the pattern. The sand may now be packed around the model up to the most prominent part of the ridge. It should be finished smoothly around it, slightly descend- ing toward the model, so as to form a thick edge of sand for the more Fig. 230. Fig. 232. Fig. 231. Fig. 230.—The lower section of the flask slightly opened to show joints. Fig. 231.—The upper sec- tion. Fig. 232.—The lower section closed, and confined by a pin, with the plaster model placed in it. perfect parting of the flask. The sand and face of the model must noAV be covered with dry pulverized charcoal sifted evenly over the whole surface. When this is done, the upper section of the flask is placed over the lower, and carefully filled with sand. It is then raised from the lower one, which may now be parted by removing the long pin, and the model gently taken away. When closed, and the tAvo put together again and inverted, it is ready to receive the melted metal." After the metal has cooled, it may be removed and turned over, so that the face of the die shall be upAvard, \vhile the remainder is buried in the sand. Thus placed, it is encircled with the ring (Fig. 231), and the metal for the counter-die poured upon it. The metals most commonly used, Avhen metallic dies are made by sand moulding, are zinc and lead. For many reasons, these are, per- haps, the best metals for general use that can be employed. Zinc is the hardest metal that the dentist can conveniently melt. In case of DIES AND COUNTER-DIES. 561 deep or large arches, and for mouths Where the mucous membrane is very hard, should its shrinkage prevent the close adaptation of the plate, a finishing die may be made of block tin, type-metal, soft solder, or Babbit's metal (a patented alloy of copper, tin, and antimony, Avhich can be obtained at any machine-shop), Avhich last is nearly as hard as zinc, and has decidedly less shrinkage. When a metal softer than zinc is used, several dies will be necessary to complete the swaging. Prof. Austen, by careful experiment, found that an average-sized zinc die, measuring two inches transversely, contracts 27-1000ths of an inch from outside to outside of the alveolar ridge, being equivalent in thickness to three ordinary book-leaves. He remarks: "In the first case, (upper jaw,) the plate would 'bind,' and if the ridge Avere covered by an unyielding mucous membrane, it Avould prevent accuracy of adaptation. In the second case, (under jaAV,) the plate Avould have too much lateral 'play/ and consequently lack stability. Again, in a moderately deep arch, say a half inch in depth, the shrinkage between the level of the ridge and the floor of the palate will be nearly 7-1000ths — rather more than one leaf. In the deepest arches, this shrinkage may give trouble, except where the ridge is soft, and then it becomes a posi- tive advantage. In the shallower cases, it is not of much moment, as there is no mouth so hard as not to yield the 1 or 2-1000ths of an inch." A counter-die should be soft. Lead is decidedly the best metal for this purpose; tin may be used if the die is made of zinc. It is desirable, if practicable, that the metal last poured (in sand moulding, this is the counter-die) should melt at a loAver temperature than the other. In this respect, zinc and lead are admirably suited — zinc melting at 770° and lead at 600°. Tin melting at 440° might be supposed, in this re- spect, better than lead ; but such is not the fact, owing to the tendency of tin and zinc to form alloys, whilst lead and zinc have no such affinity. In a paper on metallic dies, published in the fourth volume of the Am. Journal of Dental Science, Prof. Austen gives, as the result of careful experiment, the following tabular view of the fusible alloys —zinc being introduced for the purpose of comparison: CON- Melting Hard- Brittle- Point. 770° ITT. ness. NESS. 1. Zinc . •01366 •018 5 2. Lead, 2; tin, 1 . 440° 00633 •050 3 3. Lead, 1; tin, 2 . . . 340° 00500 •040 3 4. Lead, 2; tin, 3 ; antimony, 1 . 420° 00433 •026 i 5. Lead, 5; tin, 6; antimony, 1 320° 00566 •035 6 6. Lead, 5; tin, 6 ; antimony, 1 ; bismuth, 3 300° ■00266 •030 9 7. Lead, 1 ; tin, 1; bismuth, 1 250° 00066 •042 i 8. Lead, 5; tin, 3; bismuth, 8 200° ■00200 •045 8 9. Lead, 2; tin, 1; bismuth, 3 200° •00133 •048 7 36 562 DIES AND COUNTER-DIES. The last column contains an approximate estimate of the relative brit- tleness of the samples given. As in the other columns, the Ioav numbers represent the metals, so far as this property is concerned, most desirable. Those marked below 5 are malleable metals ; those above 5 are brittle; zinc, marked 5, separates these two classes, and belongs to one or the other, according to the way in which it is managed. In all cases of melting, it is a safe rule to pour the metals at the lowest temperature at Avhich they will Aoav. It is prudent, also, to coat the metal, on which other metal is poured, with a mixture of alcohol and whiting, to prevent all chance of adhesion. One more very important caution in the melting of zinc and lead is invariably to use separate ladles; for any lead, left from a previous melting, flows from the ladle with the last portions of the zinc, and, being heavier (in the proportion of 11 to 7) and more fluid, falls at once to the bottom of the matrix, making the alveolar ridge, more or less, of a soft metal, thus totally destroying its usefulness. The elastic vapor generated by the contact of the Avater in the sand with the hot metal sometimes collects under or rises through the metal, and renders the casting more or less imperfect. This may be prevented: 1, by drying the sand; 2, by using coarse or loosely-packed sand, and avoiding too much moisture ; 3, by mixing the sand with oil instead of water. The slightest moisture on one metal, previous to the pouring of another metal upon it, will make the latter imperfect. In making metallic dies for partial cases, about three-fourths of the crowns of the teeth should be cut from the plaster model before using it for moulding. The plate can thus be fitted more easily and perfectly than can be done Avhen the teeth remain on the plaster model and zinc die; for, in the former case, the plate need not be cut to fit the teeth until it has been swaged; while in the latter, this must be done first; consequently, in striking it up, it will be drawn to a greater or less distance away from them. There is also danger of splitting the plate, in swaging it into the spaces betAveen the teeth, if these are left on the metallic die. We shall conclude the section on metallic dies by giving some prac- tical suggestions by Prof. Austen, on the properties and uses of the metals and alloys employed for this purpose. Many of the properties of these metals, though most interesting, are not practically useful to the dentist; but there are some points, for which he usually refers to his memorandum-book, that should be printed on the page of his memory. The following tables present two properties of certain metals in a form convenient for memorizing; al- though not absolutely accurate, they are quite enough so for use in the dental laboratory: DIES AND COUNTER-DIES. 563 Order of Fusibility. Order of Specific Gravity. Copper . . . 2000° Lead . . .11*5 Antimony . . 900° Bismuth . . 10' Zinc .... 770° Cadmium . . 8-5 Lead . . . 600° Tin 7-5 Bismuth . . . 503° Zinc 7- Tin and cadmium . 440° Antimony . . 6-5 In the fusibility table, copper is given to show how unsuited it is for laboratory use. Remembering that 900° is red heat, the next four numbers may be easily memorized. In the specific gravity table, cop- per 9- and iron 8" are omitted, so as to present the table in a form easily remembered. The only pure metals suitable for a die are zinc and tin; for a coun- ter-die, tin and lead: zinc makes the best die, lead the best counter-die. Copper is too hard to fuse; antimony and bismuth are too brittle; cad- mium is too expensive. All other metals used in swaging are alloys. Zinc and lead are valuable because: They are so unlike that they are not easily mistaken for each other; a very common error when alloys are used. They have no such disposition to alloy as zinc and tin or tin and lead have. Zinc is so hard, one die will suffice for many cases; three are sufficient for the most difficult. The brittleness may be corrected by the size of the die. Its shrinkage is often a decided advantage; and in some cases, Avhere it makes the plate bind on the alveolus, the contraction may be anticipated by coating these parts on the model with one or tAvo layers of very thin plaster. Zinc, after re- peated use, becomes defective; hence, a supply of new metal should ahvays be kept. No metal equals lead as a counter-die. Its weight and softness are in its favor for this purpose. A counter-die cannot be too large or heavy ; convenience, of course, limits its size. A difficult plate cannot be swaged with a small counter-die, unless the Avork is nearly completed by partial counters, hammers, etc., before using it. As regards softness, the greater the disparity between die and counter, the less will be the change in the die by the act of swaging. The plate is forced by the counter into the depressions of a die, not so much by its hardness, as by its vis inertia under the SAvaging-blows. The little disparity in the hardness of the tAvo dies is one serious objection to the use of the second class of operations. It is a common practice to use several counters, and perhaps only one die. One die may in a feAV cases suffice ; two are bet- ter, and often three; but good swaging never demands more than one counter-die, Avhere that is properly made. With zinc, lead, and one fusible alloy (lead, tin, and bismuth, equal parts), all swaging operations may be completed' Avhen the dies are 564 DIES AND COUNTER-DIES. made by sand moulding, or by pouring zinc into the impression. But since many prefer other methods of making dies, it is important to understand the subject of alloys. Experiment is here the only basis of knowledge, for no a priori reasoning could deduce the singular changes caused, and new properties developed, by alloying. The alloy of two brittle metals is always brittle, and a brittle metal usually imparts this property to a tough one nearly in proportion to its percentage. But that two tough metals can make a brittle alloy is remarkable. Malleable copper, with half its weight of brittle zinc, gives hard brass, which, though less tough than copper, is not brittle. But malleable copper, with malleable tin in the same proportions, makes speculum metal—the most brittle alloy knoAvn. A similar instance is that of lead, the softest of metals, which will, in minute quantities, make gold, the most malleable of all metals, very brittle. Another remarkable property of all alloys is fusibility. Alloys fuse below the average melting-point of their constituents. Ternary com- pounds exhibit this more strikingly than binary. The following table, in illustration of this property, will be found practically useful to the dentist in the selection of alloys. Allots of Bismuth, Lead, and Tin. Bismuth, 500°. Lead, 600°. Tin, 440°. Fahrenheit. 1 10 1 540° 2 5 1 510° 3 2 1 440° 4 1 1 370° 5 2 3 335° 6 1 2 340° 7 1 5 380° 8 1 4 4 320° 9 1 2 2 290° 10 1 1 1 260° 11 2 1 1 220° It will be noticed that two pounds of lead do not make one pound of tin harder to melt; whilst a half pound reduces its fusion-point 100°. Also, Nos. 6 and 7, though containing more tin than No. 5, are harder to melt. Again, a pound of bismuth added to alloy No. 4 reduces its melting-point 110°. No. 11 and all alloys containing much bismuth are brittle. The alloys of this table vary somewhat in hard- ness, but all are harder than tin. The "alloying metals" of the dental laboratory are copper, antimony, DIES AND COUNTER-DIES. 565 and bismuth. Copper gives hardness to zinc and tin, and is sometimes combined Avith alloys of the tAvo. But the high fusion-point of copper renders it less useful to the dentist than the other two metals. The alloy of copper, antimony, and tin (Babbit's metal) is perhaps the only one of practical interest. Its advantage over zinc, in being less liable to contract, is perhaps set off by the tendency of most alloys to change their composition by frequent melting; and the danger of mix- ing different alloys, from absence of those distinctive marks, such as separate zinc and lead. Antimony is a more valuable alloying metal. It hardens tin, but its chief use in the laboratory is to harden lead, making type-metal. Small types composed of lead 4, antimony 1, are too brittle; and large types, lead 6, antimony 1, are scarcely fit for laboratory use. In the proportion of 9 to 1, antimony corrects the excessive contraction of lead, and hardens it; yet leaves it tough, so as to resist the Woavs of swaging. It is suitable only for counter-dies. The very common opinion that antimony causes lead to expand on cooling is erroneous. The alloy has a slight expansion at the moment of solidification; but after that, it obeys the universal law of all metals, and contracts as it cools. Actual contraction depends upon the ratio of contraction and the fusion-point; thus lead contracts more than zinc because its high ratio of contraction more than compensates its loAver fusion-point. Another common error is that a zinc die poured very hot is smaller than if poured at its fusion-point. Of course, contraction begins the moment cooling begins ; but so long as the metal is fluid, it necessarily fills the matrix, and contraction causes simply subsidence of the metal. No die begins to leave the Avails of the matrix until it solidifies; hence the amount of contraction is the same in all cases. Very hot zinc copies minutely the sand surface, and thus has not that bright, smooth appearance of cooler zinc, which sets before penetrating the sand interstices ; but both are equally good. Another difference is in the greater depth in the cavity on the back of the hot-poured die. But this is not as objectionable as many think; no good mechanic strikes directly upon the die, but upon some ovoid or conical piece of metal covering this cavity in the back. Bismuth is perhaps the most valuable, to the dentist, of the three alloying metals. Antimony gives hardness, but not much fusibility; bismuth gives fusibility, but no great hardness. The table above given shows the marked effect of this metal. It is seldom used as a binary alloy, because its fluxing qualities are more fully brought out in ternary combination; also because of its expensiveness, ana its 566 SWAGING PLATES. tendency to impart brittleness. Type-metal is rendered more fusible by the addition of *05 per cent, of bismuth. Bismuth, antimony, and zinc are readily distinguished — bismuth by its great weight and characteristic pinkish color; antimony by its peculiar crystallization and its excessive brittleness. But the alloys of these metals with tin and lead have such a general resemblance, that they must, with much care and system, be kept apart in properly labelled boxes; othenvise, if more than one alloy is used, the annoy- ance caused by using one for another will more than offset their utility ; in fact, such negligence defeats their usefulness. SWAGING. A die and counternlie having been obtained, a piece of sheet lead is adapted to the former, and the dimensions of the plate marked upon it. Paper is sometimes used for this purpose, but is not so good as thin sheet lead or heavy tin foil. The pattern thus made is cut out, flat- tened, and laid upon the gold plate, and its outline marked upon it. The plate should be cut a little too large, to allow for trimming and any accidental slipping upon the die. In partial cases, the pattern should be carried partly, or fully, over the excised teeth, and no at- tempt made to fit it accurately around the necks of the teeth until the swaging is nearly or quite completed. With a pair of strong shears or snips (Figs. 233, 234), the portion of plate thus marked is cut out. Fig. 233 represents a pair of Stubb's plate-shears ; Fig. 234, a pair of Fig. 233. different construction, with longer and more conveniently-shaped handles. The blades of some shears are curved laterally ; but this form is not desirable. A fine Avatch-spring saAv should be used for curves Avhich the straight shears Avill not cut; for very short curves, around teeth for instance, a pair of cutting forceps, shaped as in Fig. 235, will be found useful. SWAGING PLATES. 567 Cutting plates to shape before SAvaging is, however, not only unne- cessary, but is in many cases a positive disadvantage. SAvaging the square plate is greatly preferable in the lower jaw, since it permits working from the centre outward. And, in both upper and lower plates, the tAvo triangular pieces outside the ridge help to prevent plaiting, or doubling of the plate. Purchased plates are ordered to pattern, on the score of economy; but the difference is trifling, since good plate-scrap has nearly the same value as the original plate, and every careful operator separates his plate-scrap from his solder-scrap and filings. After swaging is nearly completed, with partial counters and hammers, the square plate may be quickly trimmed to shape by means of a jeweller's saw. Fig. 235. The plate must next be well annealed, and partially fitted, by Avooden, horn, or leaden hammers, to that part of the die inside the ridge. There is no better hammer for this purpose than lead ; but, of course, the plate must be thoroughly cleansed of all trace of the lead before annealing. The swaging is continued by the use of partial counter- dies ; these are made by placing a rim of clay or putty around the ridge and back part of the metallic die, and pouring on it fusible metal. In this way, the plate should be perfectly fitted so far as the ridge. Then, clamping the plate between the die and the partial counter, the edge is to be gradually carried over the top and outside of the ridge with hammers and small Avooden or ivory stakes. The plate may be clamped in a vice, or by means of a string passing over the die and under the foot; but a much more convenient method is found in the use of Dr. T. H. Burras's clamps, Fig. 236. Of the two forms here given, the sliding-arm (No. 2) is preferable to the long screAV (No. 1). The application of the clamp is so plainly shoAvn in No. 1, that any description is unnecessary. It is the practice of some to cut out V-shaped pieces from the front or back part of the plate, to prevent the plaiting of the metal. This 568 SWAGING PLATES. is very bad practice, and is never called for, if due care is used in swaging, and the metal is of proper fineness. To avoid plaits, or folds, anneal often, and in deep arches carry the plate down very gradually; also take care in such cases that the plate be thick, to allow for stretch- ing or draAving. In SAvaging over the ridge, it is a very common mis- take to hammer doAArn the outside before fully striking up (with ham- mer and stakes) the parts nearest the partial counter-die. Always Fig. 236. No. 1. No. 2. make it a rule, in carrying the plate over the ridge, to swage from the centre outward, carrying the plate " home" as you proceed. In deep arches, irregular alveolar ridges, and in prominent lower ridges, swag- ing must be done slowly and with great care. All- forms of bending forceps are worse than useless. They bruise the plate, as will any steel or hard metal instruments. There"is no shape of arch or of plate which, by the above simple process, cannot be perfectly fitted with a twenty-carat plate. The elaborate forms of a window-cornice, or a jelly-mould, should teach any dentist how poor a mechanic he is, Avhen he complains of the difficulty of swaging so highly malleable a metal as gold into and over the irregularities of any mouth. And when, to save his skill, he pleads want of time, he exposes a graver deficiency — dishonesty. The fitting of the plate being thus almost completed by hammers and partial counters, it should be trimmed to its exact shape, and then SWAGING PLATES. 569 placed between a fresh die and the full counter-die, and carried "home " by several firm blows of the hammer given directly over the centre of the die. The hammer should not Aveigh more than three pounds, Avith a handle about a foot long. It is a great mistake to use a very heavy or a very long-handled hammer. The striking block may be an anvil, or a large wooden block set in sand, or on a cushion, and the base of the counter-die must rest steadily upon it. It greatly facilitates SAvaging, and makes one independent of any striking block, to have a very thick and heavy lead counter. As there is ahvays a hollow in the back of a zinc die, a conical piece of iron, steel, or other hard metal, should be placed upon it to centralize the blow of the hammer. An egg-shell, filled Avith plaster, is useful for making, at the time of mould- ing the die, several zinc blocks for this purpose. To a disregard of these precautions is due much of the difficulty, so often complained of, in the tilting or rocking of plates and dies. Throughout the entire process of SAvaging, the plate must be fre- quently annealed. It may be suddenly cooled after all except the final annealing; when the cooling must be very gradual, so as to avoid warping or springing. The malleability of gold plate Avill permit a great deal of swaging Avithout annealing ; yet the neglect of this simple operation is unsafe. One broken or cracked plate gives more trouble than the annealing of a dozen. The plate, after final SAvaging, must be taken from the counter very carefully, to avoid change of shape. Thin paper in the counter-die makes removal easier; it is also easier, when only one counter is used. Too much swaging gives the plate a loose fit. When block-tin, lead, or fusible-metal dies or counter-dies are used in swaging the plate, any portion of these metals Avhich may adhere to it should be removed before annealing; as their fusion upon its sur- face alloys them with the gold, and will render it brittle, and impair its ductility; or else eat holes in the plate at the spot Avhere the par- ticles of baser metal form an alloy, fusible at the annealing heat. This is done either by mechanical or chemical means. If acid is used, it should be dilute nitric, since sulphuric will not dissolve lead; but be very careful that the nitric acid contains no hydrochloric, else the plate Avill be acted upon. The liability of the tin or lead to adhere to the gold may be measurably prevented by oiling the plate before it is struck up. Figs. 237, 238, represent the general forms of upper and lower plates after the SAvaging process is completed. In the upper plate is represented the proper size and position of a vacuum cavity, whenever it may be thought proper to use one. The question of the cavity will be elseAvhere discussed. 570 SWAGING PLATES. If, on trial of the plate in the mouth, it does not fit properly, the operator must proceed to ascertain the cause of failure. And, first, whether it is temporary or permanent. A plate which falls, because it rocks over a hard palate, will never improve ; if, because it fails to go fully into the palate, it may daily improve, and ultimately adhere with great firmness. Most plates, made soon after extraction, fit badly until the alveolar prominences are pressed doAvn by wear. Some very hard mouths will not retain the plate until it has been worn for a time; especially if the mouth is very flat. Deep arches, or uniformly soft mouths, should retain the plate firmly from the first. Fig. 237. Fig. 238. The use of pliers, except for bending the edge into some alveolar undercut, is an evidence of bad work. The back margin of upper plates, so often adjusted in this way, is much better fitted by scraping the model at the place where the plate should bind; this should be done to a depth proportioned to the softness of the membrane. Much judgment is demanded in deciding upon the necessity for a new plate. The impression may have been badly taken, or with a material not adapted to the mouth. The dies may have been carelessly made, or the swaging imperfectly done. Trial of the plate is essential to ascertain all these points, that the articulation, soldering, etc., may not be so much additional labor in vain. The different forms of plates, full and partial, will hereafter be con- sidered. They are retained in the mouth by clasps or stays; by the adhesion of contact or by the vacuum cavity, the retaining force being atmospheric pressure; by spiral springs. These will be taken up in a subsequent chapter, and their relative merits discussed. We pass now to the step which, in swaged work, comes next in order to the fitting of the plate—the means for securing its exact relation to the natural teeth; or, in double sets, its relation to the opposing plate. These processes come under the technical head of Articulation. ARTICULATION. 571 CHAPTER X. ARTICULATION. THE term Articulation, as used in Dental Mechanics, comprehends several distinct operations, implied in the use of the terms (1) Articulating impressions, (2) Articulating plates, (3) Articulating models. In many partial sets it is best, after fitting the SAvaged plate to the mouth, to take a wax impression Avith the plate in situ. This gives the precise relation of the plate to the adjacent teeth ; and, upon appli- cation of a model of the loAver jaAV, it gives the relation of the plate to the antagonist teeth. This, and all other impressions of the relation of plates to the teeth, or to each other, in the mouth, we call articu- lating impressions. A base-plate becomes an articulating plate Avhen the articulating rim is attached which has the impress of its opposite rim or teeth. In swaged work, it is the gold plate itself; in plastic work, it is some tem- porary plate of tin, lead, or gutta-percha. The articulating models make up Avhat is technically called an "Articulator," of which there are many forms; all, however, compre- hended under three varieties, (a.) Those made Avholly of plaster poured into the articulating plates, (b.) Those in which the model portion is poured into the articulating plates; but the back, or hinged portion, is metallic, (c.) Those in which the original models are set into the articulating plates, and some complicated metallic articulator adjusted to them. Each of these classes have special advantages adapting them to various exigencies of practice. Whenever, in partial cases, there are three points of contact suffi- ciently apart to give firm antagonism, Prof. Austen's plan is to take an impression of the loAver teeth : this gives a model which antagonizes perfectly with the upper model, and makes the articulator Avithout further trouble. This plan, specially applicable to vulcanite work, is adapted to swaged work by taking the articulating impression de- scribed in the second paragraph of this chapter. Such articulators require no backAvard extension or hinge, because the articulation is determined by the articulating cusps of the teeth. In partial cases Avhere there are only one or tAvo points of antago- nism, and where, consequently, the opposition of the corresponding teeth would be uncertain, the necessity exists for some third point of 572 ARTICULATION. support. This is best given by a backAvard extension of the model, so as to permit motion of the two halves of the articulator, somewhat resembling that of the natural jaws; though many partial cases do not require such an extension. In putting this Avax rim on the plate, it is better in all cases to trim it, as is done for full upper sets; but where there are remaining teeth, the antagonism of these determines the proper closure of the mouth, and this is not essential. The plate and adherent wax are placed in the mouth; the patient is then re- quested to close the mouth naturally, imbedding the teeth of the lower jaw in the wax. While the mouth is thus closed, the wax on the out- side of the teeth and alveolar ridge is pressed closely against them. This done, the plate and wax impression are carefully removed, filled with plaster, and placed on a piece of wet paper, with the wax downward. The upper side of the plate is then oiled. As the plaster stiffens, it may be applied until it is raised half an inch above the plate, and extended back of it on the paper an inch and a half or two inches. As soon as the plaster has set, its edges may be neatly trimmed; and at the back of the surface next the paper a deep transverse or T-shaped groove should be cut, to serve as a mould for the formation of a cor- responding ridge on the half model with which this is to antagonize. This grooved surface must be coated with oil, or soap-water, or varnish, or covered with a layer of tin foil or thin paper. Then partly fill the space inclosed by the wax rim with clay, putty, or wet paper, and pour on plaster to form the other half model. In running plaster into the wax impressions of the teeth, be very careful to avoid air- bubbles and flaws, and do not oil the wax. After the plaster has set, it may be trimmed as before directed. Another and often more convenient method is to take a strip of sheet lead one and a half inches wide, and bend it to the required outline of the articulator. Pour this partly full of plaster, and set the plate, ARTICULATION. 573 after softening the Avax in Avarm water, and the wax carefully removed. The model is then varnished for greater comfort in handling, and Avhen put together may present an appearence exhibited in Fig. 239. The artist has failed in this, and in other designs of the plaster articulator, to represent the tapering shape which it is best to give to the back half of the models, for greater convenience of holding them while adapting the teeth. The fault of many plaster articulators is that they are too large and clumsily shaped. In any given case, the proper distance of the groove or hinge is the distance from the patient's external auditory meatus to the line of the front teeth or alveolar ridge. The Avidth and thickness of the articulator must vary with the size or depth of the mouth, avoiding any excess of plaster not necessary to give requisite strength. For a full upper set, or where two or more remaining molars have no antagonism, it is a very common practice to place on the plate a roll of wax sufficiently large to receive the imprint of the lower teeth, and to prevent these from closing too far by the insertion of a piece of wood buried in the Avax, and projecting at the median line. The closure is better arrested by two lumps of sealing-wax attached oppo- site the bicuspids, and trimmed to the required length before putting on the Avax. But the articulation ought to determine other points besides the single one of space. Hence the antagonizing plate should be made by adjusting a rim of wax corresponding in width to the length proposed for the artificial teeth, and trimming it until all the teeth in the loAver jaw touch it at the same instant. Instead of wax, a rim of gutta-percha may be used to represent the required length and external fulness of tne teeth. When this is satisfactorily adjusted, a small rim of soft Avax is placed upon the wax or gutta-percha, and the mouth closed as naturally as possible until the teeth touch the latter. The gutta-percha can be readily trimmed with a sharp knife. Rims thus shaped give opportunity to ascertain, by the effect on the expres- sion of the lips, &c, exactly what length and fulness of tooth suits the particular case. Gutta-percha is better than wax in arresting the closure of the teeth, and is decidedly best for the temporary articula- ting plates of plastic Avork ; but the latter is more easily attached to a gold plate, and is more easily trimmed. By making the wax cold, or by imbedding a small block of Avood opposite the bicuspids on each side, the Avax rim offers a firm resistance. There is a tendency on the part of the patient to close the mouth to one side, and too far forward; it is impossible to close it behind the natural articulation. The simplest method for regulating this is to keep the body erect, and throAv the head backAvard, so as to make as tense as possible the throat-muscles, which thus act as a bridle, and 574 ARTICULATION. almost compel a correct closure of the mouth. It may also be done by careful observation of repeated closures made by the patient while sitting in an erect natural position. The operator must avoid impressing upon his patient the necessity for an easy natural closure; such di- rections invariably defeat their ob- ject. Of course these trials are to be made before attaching the soft wax which receives the impress upon the final closure. A vertical median line, traced on the Avax, is of service in observing the articula- tion, and in the subsequent adjustment of the artificial teeth. Fig. 240 represents such a rim with its original fulness cut aAvay. For a double set of artificial teeth, the folloAving method of articu- lation is often adopted. After having accurately fitted both plates, a rim of soft beesAvax is placed between them, about an inch and a quarter in width. A piece of wood, exactly corresponding in Avidth to the proposed length of the upper and lower central incisors, is passed through the wax between the plates at the median line; or, still better, one piece on each side betAveen the bicuspid part of the plates. The whole is now placed in the mouth, and each plate accurately adjusted to the alveolar border. The patient is then directed to close the mouth until the plates are brought in contact Avith the edges of the interposed piece of Avood. This done, the plate, wax, and Avood are together removed from the mouth. But a far better method consists in placing a rim of wax or gutta- percha on each plate, giving the length, outline, and fulness respec- tively designed for the teeth of each jaw. The two plates are put in the mouth, and the jaws are carefully closed; if the rims of wax touch at any one point sooner than another, the plates are removed and the wax trimmed; this operation is repeated until the two rims of wax meet all the way round at the same instant, and give the proper con- tour to the cheeks and lips. The median line is then marked, and the final closure of the mouth made with the utmost care, so that there shall be no lateral or fonvard deviation. The exact position being secured, the lower jaw is to be held Avith the left hand, while, with the right, some six or eight oblique indentations are made with a wax-knife across the line of contact between the two rims. Some fasten them together by a warm wax-knife, or by pins, or by small slips of brass plate warmed and forced into the wax. The pieces are removed jointly ARTICULATION. 575 or separately from the mouth ; if separately, they can, by the aid of these marks, be accurately readjusted. From these articulating plates a plaster articulator is made substan- tially in the manner described for a partial case. The lead rim for shaping the models will often have to be two inches broad. If the precaution is taken to fill the space Avithin the wax rims and between the plates with paper pulp, it is not material which half is filled first. Usually the lower-jaw model will be thickest, and in this, made first, it is best to cut the grooves. Fig. 241 represents a plaster articulator Fig. 241. with the plates removed, in Avhich figure, from neglect of this point, the thin upper half is much weakened by the V-shaped cut. Partly to save plaster, but chiefly to permit modi- fication of the articulation, where inaccuracy is sus- pected, quite a number of metallic articulators have been recommended. One of the first contrived for this purpose Avas by Dr. Thomas Evans, of Paris, and made of heavy brass wire. Fig. 242 represents a very convenient form of metallic articulator. But in using this, and every similar contrivance, the operator should remember that facility of 576 ARTICULATION. changing the articulation, after the guiding wax rims are removed, is a very questionable advantage. It tempts to carelessness in articu- lating. Moreover, if the Avidth of space, or other relation of the parts, is such as leads to suspicion of inaccuracy, any change of articulation is, at best, a sort of random guess-Avork. The most certain correction of surmised error is, undoubtedly, to take the articulation anew. Hence our preference is for the old-fashioned plaster articulator, Avith its unaccommodating fixedness, that neither offers a premium on care- lessness, nor puts the careful workman at the mercy of some loose joint or screAV. There is another class of articulators more complicated than the above, which are very useful in those cases Avhere the original models are used, instead of special models cast in the articulating plates. Fig. 243. Fig. 243 is a very excellent one for this purpose, combining all the advantages of metallic articulators, with a peculiar lateral movement closely resembling that of the natural jaw. The subject of articulation cannot be dismissed without a few Avords upon the great importance of extreme accuracy in all its details. It is a very remarkable fact that some of the most painstaking dental mechanicians practise methods of articulating in which there can be no certainty, and for constant errors in which the emery wheel is re- sorted to, in order to save them the mortification of making their work anew. In fact, there is no better evidence of the guess-work character of an immense number of articulations than the habitual attempts at correction by the equally guess-work shifting of movable articulators. SOLDERING. 577 We assert, without hesitation, that any articulation — Avhether with gold plate or with the temporary plates of vulcanite and other forms of plastic Avork—can betaken in such manner as not to require the slightest change in the relation of the articulating models. We shall not insult the profession by attempting to prove that, if it can be done, it should be done. Next in importance to accuracy of the impression is correct- ness of articulation. Defects in either are damaging to one's reputa- tion. But there is this difference: that in the former the error may often be detected on trial of the plate, while in the latter case the fin- ished work alone reveals the failure. Defective articulation is a prolific source of the disgraceful short- coming of Vulcanite Dentistry. By these terms we specialize that art, and its accompanying science, Avhich begins with Hard Rubber and ends with a Vulcanizer; Avhich knows nothing of the uses of gold save as a circulating medium, recognizing no quality in a dental mate- rial so highly as its cheapness, no merit in a process so valuable as its rapidity. So long as such principles rule in the dental laboratory, carelessness in articulation is of little consequence. But older practi- tioners, who are accustomed to handle the royal metal Avith a care worthy of its high character, will fully appreciate the great import- ance of a rigorously exact articulation. CHAPTER XI. PRINCIPLES AND APPLIANCES OF SOLDERING. SOLDERING is the union of two metallic surfaces; either by slightly fusing the surfaces themselves (technically termed sweating, or autogenous soldering), as in the union of a plate of silver to a block of copper preparatory to rolling it into Sheffield plate; or by the fusion of an alloy Avhich melts more readily than the metals to be soldered. The conditions of successful soldering, as given by Prof. Austen, are: 1. A freely flowing solder. 2. Absence of oxide from the surface over which the solder is to Aoav. 3. Proper amount and direction of heat in floAving the solder. The first condition requires good solder; of this Ave have elseAvhere spoken. The second calls for the use of borax, the specific action of Avhich, as a flux, is — first, the removal of existing oxide by virtue of its poAverful affinity for it; secondly, the prevention of further oxidation by the exclusion of the oxygen of the air. The third condition demands a skilful management of the blow- 37 578 SOLDERING. pipe flame; this is the principal difficulty with most beginners, and, indeed, with not a feAV old practitioners. The borax should be used in the lump, and rubbed with pure (dis- tilled or rain) water upon a coarsely-ground glass slab until a creamy paste is formed. Into this the pieces of solder may be placed, and also some of it applied, with a small brush or feather, to the surfaces over which the solder is required to flow. Hard water and the common practice of rubbing borax on a slate make it impure, and, to some extent, interfere with soldering. Too much borax is objectionable, and gold requires less than silver. In fulfilling the third condition — the management of the heat — the following points demand attention: (a) To raise the heat very gradually until the Avater of crystallization of the borax is sloAvly driven off; for if this is done rapidly, the borax puffs up and throAVS off the solder; rapid heating at the outset is apt also to crack the teeth. (6) To diffuse the heat, when using the blow-pipe, so that the solder shall not become melted before the metallic surfaces are hot enough to unite Avith it; else it will roll into a ball, or Aoav with an abrujjtly- defined edge; whereas it should unite so smoothly with the plate that, except for the difference in color, its line of termination cannot be detected, (c) To manage the fine point of the blow-pipe flame so as to be able to direct the Aoav of the solder to any given point; the rule being, that, unless prevented, solder will flow toAvard the hottest point. There are two kinds of flame given by the blast of the blow-pipe: 1. The broad, heating-up, or oxidizing flame; this is produced by holding the tip a little behind or at the edge of the flame. 2. The pointed, soldering, or deoxidizing flame; this is produced by passing the tip more or less into the flame. A very general mistake is to use too strong a blast. The apparatus required for soldering includes a lamp to give a suffi- ciently hot flame; a bloAV-pipe to give intensity and direction to the flame ; borax, brush, glass, slate, solder, and solder - tongs; investing materials and clamps, to protect the teeth, also to hold the parts in relation to each other until soldered; a recep- tacle to retain or give additional heat during the process of soldering; an acid (sulphuric) bath to remove the glass of borax. The simplest form of lamp is shoAvn in Fig 244, holding about a pint, and having a wick three-fourths of SOLDERING. 579 an inch or one inch in diameter. As accidents sometimes occur from the flame communicating with the explosive mixture of air and alco- holic vapor in the body of the lamp, it is prudent to make a safety- lamp by connecting the wick-tube with the body of the lamp by a small tube, Avhich shall be, under all circumstances, full of alcohol. Fig. 245 represents such a lamp. If the wick is not permitted to run below the shoulder above the horizontal tube, this tube will remain always filled with alcohol. The top of the wick-tube should be bevelled off in a direction just the reverse of that shown in the draAving, so as to permit the downward projection of the flame. Fig. 246 is a very ingenious modification of the safety-lamp, made by Dr. B. W. Franklin, so con- structed as to retain the al- cohol uniformly at the same level. The fluid used in these lamps is usually alcohol. For all purposes of dental soldering, alcohol gives a suf- ficient degree of heat, and is much more cleanly than the carboniferous flame of ethereal oil, sperm oil, coal oil, or gas. To give intensity and proper direction to the heat of the lamp, a blow-pipe is necessary. The simplest is a tapering tube, fifteen to eighteen inches long, and curved at the smaller end (Fig. 247). At this end the bore for the last half inch should heperfectly cylindrical, and about as large as a medium-sized knit- ting-needle. This may be modified in several ways, and made more useful. First, by cutting it Avithin three inches of the flame-end, and inserting a small IioIIoav ball or cylinder to receive the condensed moisture, which, in the plain bloAV- pipe, often interrupts the blast. Secondly, by at- G taching a flattened mouth- piece, Avhich it is much less fatiguing to the lips to grasp. Thirdly, by connecting the flame- end to the mouth-piece by from six to twelve inches of flexible tubing. 580 SOLDERING. The flame-end ought to be straight, and from four to six inches long: a cigar-holder makes an excellent mouth-piece. A bulb or enlarge- ment in the tube might be serviceable in retaining condensed moisture; but it is less liable to accumulate in rubber-tubing than in the metal pipes. There are many forms of mouth blow-pipes, and some quite ex- pensive ones; but the pipe with flexible tube, as here described, will be found altogether the most convenient for the laboratory. The mouth blow-pipe requires in its use a peculiar management of the muscles of the chest, cheeks, and palate, by virtue of which an uninterrupted and regular current of air is thrown from the lungs through the pipe. The simplest way to learn how to do this, is to first practise blowing exclusively during inspiration: this calls into action the cheek-muscles,, and involuntarily closes the opening between mouth and fauces. Then use the pipe solely during expiration: this teaches control of the chest-muscles in the emission of a steady, gentle blast. The art of using the blow-pipe, Avithout fatigue, consists in alternating the action of these two sets of muscles: the art of giving a perfectly steady, uninterrupted blast implies complete control over these muscles, and the ability to pass from one set to the other at the moment of opening or closing the entrance to the fauces. After persevering prac- tice of the two methods of blowing, the art of connecting them will come almost unconsciously: when once learned, it is never forgotten. Those Avho are too indolent to master the first difficulty of learning it, become the slaves to mechanical appliances, which, however useful for Fig. 248. many purposes, can never supply the place of this simplest and best of all blow-pipes. Blow-pipes working by artificial blast may be divided into four classes: 1. Alcoholic or self-acting blow-pipes; 2. Mechanical or bel- SOLDERING. 581 Fig. -249. lows blow-pipes; 3. Hydrostatic bloAV-pipes; 4. Oxy-hydrogen or aero- hydrogen blow-pipes. Of each of these Ave shall give an example. To enumerate all the forms that inventive talent has devised would fill too much of our space. The self-acting blow-pipes derive the force of their blast from .the vapor of hot alcohol, Avhich, igniting as it passes through the flame, adds to the intensity of the heat. A someAvhat complex, but very complete, blow-pipe of this class, invented by Dr. Jahial Parmly, is shoAvn in Fig. 248. The lamp G, supplied from the reservoir D D, heats the alcohol in globe I, supplied from the reservoir J, through the pipe N. The elas- tic vapor escapes at the jet P, giving intensity to the large flame L, which receives its supply of alcohol from reservoir M J. Both upper and lower wick-tubes have movable cylinders for regulating the flame. A small charcoal furnace, R, may be brought in range of the flame for melting purposes. Smaller and more portable lamps are made, of Avhich quite a num- ber of different patterns are to be found in the depots. The principle and general plan of construction are very clearly shoAvn in Fig. 249, de- signed by Dr. S. S. Wrhite. All al- coholic bloAV-pipes give intensity of heat, but are greatly inferior to the mouth blow-pipe in the control Avhich the operator has over the force and direction of the jet. The different forms of the me- chanical blow-pipe are almost infi- nite. The principle of construction is either that of the belloAvs or the force-pump combined Avith a reser- voir of air to give uniformity to the blast, which would otherwise issue in jets. A common house-bellows, secured to the floor, will form a simple and good arrangement. A spring should separate the handles, the upper one of which forms a treadle. An India-rubber pipe should pass from the nozzle to an air-tight box, from which a second tube comes out and is attached to the blow-pipe. If the belloAvs is made double, like a blacksmith's, the upper half forms the air-chamber, in place of the air-tight box. Fig. 250, taken from S. S. White's illustrated catalogue, represents a foot-bellows and regulating air-vessel, applicable to the spray appa- 582 SOLDERING. Fig. 250. ratus. It may also be used in the laboratory for soldering, and cornea in this class of blow-pipes. In Fig. 251 is shown a double - cylinder bellows, ten inches in diameter, moved by a treadle attached to the rod d f, which passes under the soldering-table. In the drawing it is combined Avith an alcohol blow-pipe, as designed by Dr. W. H. Elliot, of Montreal; but it may be used independently by attach- ing a flexible tube, with brass point, to the air-pipe a a. The following remarks by Dr. Elliot, upon this combination, will be found very instructive. " The fact that the centre of the flame of the self-acting bloAV-pipe contains no oxygen is well known to every enlightened dentist, and may be proved by placing a rod of pol- ished metal in the flame for a few seconds, in which case it will be seen that the surface of that portion of the rod occupying the centre of the flame does not unite with oxygen, hoAV- ever great the degree of heat may be; but if a jet of atmospheric air be thrown into the flame upon the rod, it will oxidize as readily as if heated by any other means. This little experi- ment proves not only the want of oxygen in the flame, but it leads to the very im- portant conclusion that, without oxy- gen, the burning of the vapor must be gradual and imperfect. In consideration of this fact, the writer was led to make the experiment of producing a more perfect combustion by throwing into the flame one of its supporters. This may be done in several ways ; but the simplest and most conve- nient is atmospheric air, thrown in by means of a bellows. The air irom the lungs will not do as well, inasmuch as it not only contains SOLDERING. 583 less oxygen, but also contains a large portion of carbonic acid, which just so far renders it unfit for the support of combustion. " The air-pipe should pass along by the vapor-pipe, and discharge about an inch and a half beyond it in the very centre of the flame, and in precisely the same direction. The calibre of the air-pipe at its apex must be equal to that of the vapor-pipe. It must be made as small as possible without being enlarged at the end, as any enlarge- ment there Avould derange the vapor-flame. It must also be con- structed of platina, as that is the only metal which will resist, for any length of time, the heat of the burning vapor. " The air-pipe appears to throAv out a pale blue flame, about two inches in length, small and pointed. At the very point of this flame, the oxygen being all consumed, the greatest amount of heat is pro- duced, and the fusion of the solder takes place Avithout oxidation ; but within the blue flame, where oxygen preponderates, oxidation of the solder goes on rapidly. The extra heat gained by the introduction of the air-pipe is nearly all concentrated at the apex of the blue flame, which may be brought to bear upon the point to be soldered, while the vapor-flame keeps up the temperature of the whole work." Dr. R. Somerby, of Louisville, has constructed a combined furnace and blow-pipe, Avhich will be found very convenient and useful in the laboratory (Fig. 252). The double belloAvs o, worked by the treadle r, sends its blast —which may be increased by the weighty—up the pipe n, either to the furnace i, or through the blow-pipe d, into the flame of the lamp b, which rests on a sliding-ring / attached to the movable stand h. The frame is of cast-iron, the pipes of brass, the lamp 584 SOLDERING. of copper, and the entire apparatus admirably made, and of the best material. When the furnace is used, a hood, resting against the flange a, carries off the smoke, and a panj receives the ashes. If desirable, the fire may be started by the blast, and then continued by simple draft Fig. 252. through the door k; this can be made of any required intensity by a pipe set directly over the top of the furnace. The process of soldering is rendered more easy by this blow-pipe than by the usual method, and is, therefore, valuable to those of the profession who are stationary, SOLDERING. 585 and occupy themselves much in mechanical dentistry. The furnace attached to it answers all the purposes of melting gold, solder, and metallic casts. The third class of blow-pipes is sometimes combined with the second to regulate the blast, or with the first to intensify it. In its uncom- bined form it consists essentially of a blow-pipe .point attached by a flexible tube to an air-chamber, from which the air is forced by the steady pressure of water. When once set in operation, it is self-acting, and in this respect has great advantage over the second class. This, Avith the perfect regularity of the blast, makes a properly-constructed hydrostatic blow-pipe, much the best of all substitutes for the lungs and mouth blow-pipe. The gasometer of the nitrous oxide gas apparatus makes a very excellent hydrostatic blow-pipe. Its form, and the manner of using it, are so familiar to dentists as to render any illustration or description unnecessary. Any required force of blast may be given by detaching the counterpoise, or by adding weights to the descending cylinder. Prof. Austen gives the folloAving description of a simple and inex- pensive apparatus suitable for laboratories where no pressure can be had, as in cities, from public Avater-Avorks. " Place in convenient posi- tion a strong ten-gallon Avater-tight oak-cask, two feet from the floor. Over this, and two feet above it, place a second of the same size, with a movable cover, so that water may be conveniently poured into it. Connect the casks by a tube running nearly to the bottom of the loAver cask, and having a stop-cock a betAveen the casks. Into the top of the loAver cask insert a stop-cock b, to Avhich attach the bloAv-pipe tube, and into the bottom a larger stop-cock c for draAving off the water. It is prepared for operation thus : close all the stop-cocks, and fill the tipper cask to within an inch of the top (if too full, it might chance to overflow the lower cask and force water out of the bloAv-pipe upon the flame and work) ; then open stop-cocks a, b, and the jet will issue with a force proportioned to the height of the water. If too strong, it may be regulated by pressure upon the elastic tube, or by partly closing the stop-cock. Ten gallons of air will suffice for any ordinary case of soldering; but the process is easily reneAved by closing stop a and drawing off the water by stop c from the lower cask, and emptying into the upper. This can be more rapidly done if stop b is left open, so as to admit air freely while drawing off the Avater. Another, but more expensive form, is shoAvn in Fig. 253, made of copper or boiler-iron, and connected by lead pipes Avith the public Avater-works. in towns and cities thus supplied. The drawing, taken in connection Avith the previous description, makes any explanation un- necessary. 586 SOLDERING. Fig. 253. The fourth class of blow-pipes is analogous in its operation to the oxy-hydrogen blow-pipe. The point is double, consisting of a tube, through Avhich comes the supporter of combustion (oxygen or com- mon air), surrounded by a cylinder, through which comes the com- bustible (alcoholic vapor, illuminating gas, or hydrogen). In Count Richmont's aero- hydrogen blow-pipe, the hydrogen is gener- ated in a vessel by the action of dilute sul- phuric acid upon zinc, and the air forced through the centre tube either with a bellows or from the lungs. The heat is less intense than that of the oxy-hydrogen blow-pipe, but is too great for most laboratory purposes. The gas blow-pipe is a very convenient in- strument : the principle is similar, and the heat very great. Fig. 254 represents Macomber's gas blow- pipe. The direction of the point 1 is regu- lated by the joint 3, and the supply of gas controlled by the stop-cock 2. The air is supplied from the lungs, or from some form of mechanical or hydrostatic blow - pipe, through the flexible tube. In the operation of soldering, the parts to be united must be held together in their exact relative position. This can sometimes be done by simply laying them together; but usually they must be held in place, either by iron wire bound around them, or by small clamps of iron wire, or by rivets; or else by some investing material, which, in dentistry, is always plaster mixed with some substances that Will counteract its tendency to shrink and crack under soldering heat. This substance maybe coal ashes,soap- stone dust, felspar, clean sand, or as- bestos. The two latter are the best, and may be mixed in proportions varying from two to six parts sand or asbestos to four of plaster. As a rule, the less but a very small quantity makes the j-j^llllii.uiiiivn-^-^ —~ IT Fig. 254. plaster, the less shrinkage; investment too friable. A common mistake is to use too large a quantity of investing SOLDERING. 587 material. This almost invariably results in the Avarping of the plate; for, as all investments have some degree of permanent contraction, and all metal must expand, if the latter is bound by a rigid, unyielding mass, it will inevitably warp. Hence, as a rule, use no more investing material than is necessary to keep the parts to be soldered in their position, and to protect the porcelain surfaces from direct contact Avith the flame. This subject will be further considered, when speaking of the soldering of teeth to the plate. In selecting a suitable receptacle for the work to be soldered, it is important to retain the heat, especially when using the mouth bloAV- pipe. A funnel-shaped mat made with scraps of Avoven iron-wire; or a large lump of pumice-stone; or one of close-grained charcoal, with the outside coated over with a thin layer of plaster, form very simple and convenient receptacles for smaller pieces of Avork. For larger Avork, or for very high temperatures, it is important to receive additional heat from ignited charcoal, for Avhich purpose the soldering-pan (Fig. 255) is a very admirable contrivance. The movable lid remains during the heating up and the cooling off, but is, of course, removed during the act of soldering. Fig. 255. After soldering, the work should cool gradually, unless it is to be re-SAvaged. If there is any porcelain attached, the cooling must be very gradual. When cold, it may be placed in dilute sulphuric acid and slowly raised to the boiling-point, kept there for a few moments, and then sloAvly cooled. This dissolves the glass of borax, which is so hard that it injures the edge of files and scrapers. 588 SOLDERING. A few general considerations may be of service in the use of the above described appliances for soldering. It is an operation regarded by many as attended with much risk; and by students generally it is considered the Pons Asinorum of dentistry. Whereas, there is no pro- cess in dental prosthesis in Avhich the desired result can be with more certainty obtained, provided such care and skill are exercised as alone can give success in any department of the art. Plates warp from want of support when heated, or from excess of investing batter: they are burnt, blistered, or melted, from careless or ignorant use of the blow-pipe. Teeth are broken from rapid heating or cooling ; they are displaced by the shrinking of an ill-judged invest- ment. Solder is condemned because it will not bridge a chasm one- eighth inch wide, will not run over plaster, Avill not attach itself to an oxidized surface, or will obstinately roll up into a ball, rather than Aoav over a surface too cold to receive it. These, and all other vexations of soldering, are the result of haste, ignorance, or want of skill. In soldering two surfaces, as in the doubling of loAver or shallow upper plates, the borax must contain no particles preventing contact of the plates ; also the heat must be directed on the side opposite the pieces of solder, so that, Avhen melted, it may flow between the plates from one side to the other. Clamps are preferable to plaster batter for holding parts together, whenever practicable, as in soldering a wire or band around plates ; but when the relation must be preserved with utmost accuracy, as in clasps, the plaster investment is essential. It is also necessary for the protection of porcelain from the direct action of flame. In soldering teeth to a plate, the batter must have such proportion of plaster with asbestos or sand as to admit of being used in small quantity, and yet be so strong when heated that it will not crack, and endanger the position of the teeth. Backings and clasps must fit accu- rately wherever they are to be fastened. There should be no trace of plaster on a surface Avhere solder is to flow ; or, in fact, substances of any kind except borax, and not too much of that. Borax must be pure and clean, and used with soft water, and the heating must be gradual, in view of its liability to throw off the solder. Solder must be of good quality and carefully placed, never putting two pieces where the position will alloAV the proper quantity to lie in one piece. It is a very common practice to cut solder into very small pieces, under the idea that it will flow more evenly ; but if a plate is properly heated and the blow-pipe flame skilfully managed, the large pieces melt in- stantly, and flow into their proper position. It is quite possible, by careful observance of these directions, and by expertness in the management of the blow-pipe, to solder any set of ADJUSTMENT OF TEETH. 589 teeth so that there shall be no roughness or abrupt edges requiring the use of files and scrapers. In fact, these tools are never needed to give finish to a perfectly-soldered joint: the natural Aoav of the solder takes a shape which cannot be improved. CHAPTER XII. ADJUSTMENT OF PORCELAIN TEETH TO THE PLATE — FINISHING PROCESS. WHERE vacancies between natural teeth are to be filled, it is highly important that the artificial teeth should correspond in shade and color Avith the natural organs; for in proportion as they are Avhiter or darker, will the contrast be striking, and their artificial character apparent. Of the two faults, it is better that they should be a little darker than any Avhiter. They should also resemble in shape those Avhich have been lost, so far as it is possible to ascertain this. Minute accuracy as to shades of color, involves the necessity of a large assortment, unless one is located near a depot or agency. But the facilities of mail and express greatly lessen this necessity, provided there is time to send for the tooth or teeth required. It is desirable, in vieAV of this method of matching shades of color to keep all refuse or broken teeth, to be used as samples in sending orders. The manufacturer supplies three varieties of plate-teeth,— plain, gum, and sections. The latter have the advantage of showing few joints, but are less easily repaired, and are not applicable to so wide a range of cases. Gum teeth or sections are applicable only Avhere there has been sufficient absorption to permit the extra fulness of the artificial gum. Many mouths are deformed by a foolish craving on the part of the patient, which the dentist is equally foolish in yielding to, whenever plain teeth are more appropriate. In point of strength, durability, and facility of repair, plain teeth are superior to the others ; they are also more readily adapted to the plate. The manufacture of gum teeth, in sections of two, three, or four teeth, has been brought to such perfection that comparatively few single gum teeth are now used ; especially since neAV methods of at- taching these sections to the plate have rendered unnecessary that exact fitting of blocks which Avas one objection to their use. This perfection of manufacture has also done away with the necessity, on the part of the dentist, of devoting to the making of block teeth the very large 590 ADJUSTMENT OF TEETH. proportion of his time formerly demanded by this difficult process. Whenever special cases demand blocks or sections made to order, it will be found more satisfactory to send proper models and descriptions, and have such teeth made by those who are thus constantly occupied, than to incur the disappointments and delays inevitably attendant upon infrequent and irregular attempts at block work. For the proper shaping of models or articulators to accompany such orders, directions will hereafter be given. These blocks, when received, do not need much, if any, grinding. But all plain teeth, single gum teeth, and ordinary sections or block teeth require, after selection, to be more or less accurately fitted to the base-plate. For this purpose they must be ground on emery- or corundum-wheels until accurately fitted, and must be so arranged, in full cases, as to meet the teeth Avith Avhich they are intended to antagonize at the same instant around the entire arch: in partial cases, the natural teeth should touch their antagonists more decidedly than the artificial ones. A correct articu- Fig. 256. Fig. 257. lation will enable the dentist to antagonize the teeth Avith perfect accuracy. In arranging an entire set for the upper, or for both jaws, the molars should be so adjusted that the inner or palatine tubercles come together before the outer ones. This precaution is necessary in antagonizing single as Avell as block teeth. If the outer tubercles strike first, the pressure there will spring and loosen the plate. For the same reason 4345974� ADJUSTMENT OF TEETH. 591 Fig. 258. upper molars and bicuspids should not be set so that the force of mastication falls outside of the ridge. A small space should be left between the last tooth of the upper and of the lower jaw, in those cases where the crown of the lower molar looks forward, its posterior edge being a little higher than the anterior. It is often necessary to cut away a considerable portion of a tooth in order to make it fit accurately to the plate. This makes the process of grinding very tedious, unless the operator has a number of sharp- cutting corundum-wheels, varying from half an inch to three or four inches in diameter. These wheels may be attached to one of the hand-lathes on pages 509, 510, or to Coy's noiseless hand lathe, Fig. 258.° The foot-lathe is, however, far more con- venient for laboratory use, where much grinding is to be done. Of these, the depots furnish some excellent varieties. Fig. 256 represents an admirable lathe for dental purposes; while, in Fig. 257, Ave have a larger, stronger, and more powerful lathe, capable of very rapid mo- tion; also adapted to the making of small instruments, handles, etc. Figs. 259, 260 represent a piece of cabinet furniture combining lathe, work-table, and drawers for implements, materials, etc., specially de- Fig. 259. Fig. 260. 592 ADJUSTMENT OF TEETH. signed for those who, having laboratory and office in one room, may Avish to unite utility and ornament. The lathe of Dr. Lawrence, with detached driving-wheel and head, that can be attached to any convenient board, shelf, or table, (Fig. 261,) has advantages that will make it very desirable to many. Fig. 261. Wheels may either be set at intervals on a long spindle (Fig. 257), or screwed singly on the end of the mandril (Fig. 256). In the latter case they should be fixed with a screw-chuck in the centre, so as to be quickly changed from coarse to fine, or from large to small. In grind- ing, the wheel should revolve toward the operator, and be kept con- stantly wet with a sponge held either in a sponge-holder or between the ring-finger and little finger of the left hand. The thumb and forefinger of each hand must be free to hold the tooth, the right wrist being steadily supported on the hand-rest. Two faults are very common in grinding: one is, revolving the wheel too rapidly ; the other, bearing the tooth too heavily against the wheel. The first hinders rather than helps grinding; the second is very apt to throw the tooth from the fingers, and destroys the delicacy of touch necessary for accurate grinding. In grinding blocks and gum teeth, and often in plain teeth, very small Avheels are required to make them fit the curves of the plate. Thin edges of gum teeth and blocks must be ground with very fine- grained wheels; in jointing them, a three-inch wheel should be used, perfectly flat on its outer side, and running very true. Wheels, when worn doAvn to small size, increase in value because they grind out curves inaccessible to larger ones. In warm weather, large and thin wheels, when not in use, should rest on a flat surface; such wheels are often warped by the softening of the shellac as they lie carelessly among other wheels. Wheels running on the end of a mandril, and ADJUSTMENT OF TEETH. 593 attached by a screw-chuck, can be made to run true by warming the mandril with a spirit-lamp, and at the same time revolving the wheel rapidly. The accuracy of fit necessary depends upon the kind of work and mode of attachment to the base-plate. In general terms, it may be stated that whenever any permanent plastic material is in contact with the base of the teeth, or forms the bond of union between the teeth and plate, grinding is much simplified. It is sometimes better, in such cases, to have a moderate space between the base of the tooth and the plate or the model, than to have actual contact But in all cases the lateral jointing of block or single gum teeth requires care. The order of grinding a set of teeth is usually to fit the central incisors, then the laterals, next the bicuspids, and so on; in case of sections, in the same order. This order will be found most conducive to uniformity of arrangement; of course, it may be modified to any desired extent. In case of a double set, there is much diversity of practice. Some adapt, first, the entire upper set, others, the entire lower; some, again, adjust the two sets of incisors, then the bicuspid blocks of both pieces, lastly, the molars. Whichever method is adopted, when all or part of one of the articulating rims is removed, the antagonizing rim must be retained, to guide in the adjustment of the teeth. During the process of grinding, the teeth are temporarily attached to the plate in several ways. Either the articulating rim is cut away sufficiently to receive the tooth (Fig. 262), or the rim is entirely removed, and its place supplied with a mass of wax covering the plate to the top of the ridge, and to which* the teeth are severally attached as they are ground; others fasten the teeth to the plate with cement. Definite rules of arrangement, or wood- cuts illustrating various forms of teeth and manner of setting them in the arch, are not all that is necessary. This branch of dental aesthetics must, of necessity, be worked out by every one for himself. He will succeed or fail just in proportion as he has the ability to observe the hundreds of models which are perpetually before him; and as he has the further and rarer ability to apply his observations to the special cases that are in his laboratory. Imitation of nature is the rule. Limitations of art> and individual incapacity, make exact observance of this rule comparatively rare. We replace the sixteen teeth with only fourteen, and often make them shorter and every way smaller than the natural organs. We do not make the grinding surfaces interlock with such deep cusps as in nature. 38 594 ADJUSTMENT OF TEETH. At one time we cannot avoid an unnatural fulness of artificial gum; at other times, the contraction of the absorbed arch compels the set- ting of molar teeth nearer the median line than the original teeth. NotAvithstanding these and many other disadvantages, the perfection of the dento-ceramic Art is such that a skilled artist, who is quick to observe what nature requires, can, in the majority of cases falling under his care, supply the lost dental organs with great accuracy, and preserve that higher order of beauty which groAVS out of the harmony of his Avork Avith the expression of the face and entire person. But no dentist can give to his work this kind of beauty who does not sys- tematically study the natural organs as they daily present themselves in the operating-chair. Few patients would object to the pressure of a roll of wax (two inches long and about a half inch thick) against the closed teeth. A model from this impression would give the size, form, arrangement, and articulation of all except the molar teeth. A Avell- matched porcelain tooth (more than one might be required) would add to these data the color of teeth and gum. To this add also the age, sex, physical characteristics of the face, and the physical temperament. If the dentist Avould have a case and book for the registration of one such carefully made observation every week, he Avould, at the end of two years, have a collection Avhich, as a practical guide in the selec- tion and arrangement of artificial teeth, would prove of incalculable value. These fixed records of minute details are made still more use- ful by a habit of close observation in society. In this way a set style, or mannerism, may be avoided, which so often stamps dental work with meaningless uniformity of expression. Artificial teeth should imitate the natural organs ; yet there is a perfection of form and arrangement AAhich it is not advisable to imitate. To disarm suspicion as to their artificial character, it is often desirable to impart a measure of irregularity. An overlapping lateral, a missing bicuspid, a worn canine, an incisor bicuspid or molar apparently de- cayed and filled with gold, an exposed neck from absorption of the alveolus, are among the legitimate devices of the skilful mechanician who has the "art to conceal his art." If there are any defective natu- ral teeth remaining to be matched, still higher art is required. A per- fect porcelain incisor is no fit companion for one that is partly broken, decayed, and discolored; and since no art can make the defective tooth perfect, and yet the patient retains it, there is no alternative but to give so much imperfection to the artificial one as shall take away that striking contrast which so painfully offends our aesthetic sense of fitness. In this class of operations a "diamond drill" is of great value; in fact, so very useful is it in many ways, that we regard it as an abso- ADJUSTMENT OF TEETH. 595 lutely indispensable instrument in the laboratory. Cutting away parts of teeth or blocks inaccessible to Avheels ; changing the shape of teeth near the gum ; drilling cavities to be filled Avith gold, or holes for the repair of broken blocks, these are some of the operations which the diamond drill will accomplish as no other instrument can. The selection and grinding of artificial teeth requires, first, a high order of aesthetic culture; secondly, great patience and skilful manip- ulation. The latter are often taxed to the utmost to make a set of blocks ansAver the requirements of a given case; especially when the blocks must be closely fitted to a gold plate preparatory to attachment by soldering. Single gum teeth are more easily fitted to the plate; but there are more joints; hence it is doubtful if much time is saved. The principal advantage of single gum teeth is, that a single tooth, if broken, may be replaced without interfering Avith the adjoining ones. Another reason A\hy many prefer them is, that a small stock of teeth in this form is adapted to a larger variety of cases than blocks would be. We think, hoAvever, that dentists living at a distance from the manufacturer should depend upon a great variety of samples rather than upon duplicates of certain forms, however desirable. It is a matter of some surprise that manufacturers have not long ago recog- nized the advantage of preparing "sample cards," numbered and let- tered ; so that any desired size, shape, and color of teeth may be ordered by mail or express, as they are required. These samples should be so made, however, that the "card" could not be injured by the temptation to use them in practice. In jointing a set of blocks or single gum teeth, one point must be remembered which has been already alluded to. In soldering, the metal expands, Avhile the teeth held in the investment are brought closer together by its contraction, and in this slightly-altered position they are soldered to the plate. The contraction of the plate on cool- ing is irresistible, and may result in one or both of tAvo accidents — chipping off the brittle edges of the teeth thus brought too closely together, or warping the plate because of the resistance Avhich the teeth or blocks offer to the contraction of the plate. Thin letter-paper slipped between the side-joints will suffice to prevent these accidents. Fig. 263 gives an external vieAV of a full upper set of single gum teeth, arranged on a gold plate, preparatory to the operations which precede soldering, or other modes of fastening them to the base. Fig. 264 is a similar view of a set of blocks, Avith a soldered rim covering the upper edge. Usually, in first or temporary pieces, and sometimes after the alveo- lar absorption is completed, the fulness of the gum is such as to forbid 596 ADJUSTMENT OF TEETH. the addition of an artificial gum to the ten incisors, canines, and bicus- pids. In such cases the plate must be cut away from the front of the ridge as far as the first or second bicuspid, and the teeth ground with great accuracy to fit the gum itself. Single plain teeth will usually be best adapted to such cases; but an excellent effect can sometimes be Fig. 263. Fig. 264 produced by grinding a block, when the shade of gum is well matched, to fit directly upon the natural gum. In partial cases the tooth or block must invariably be fitted to the gum; no plate should be seen above or at the side. In fitting directly to the plaster model, this should be scraped (after the tooth is ground), so that it may press firmly on the corresponding gum. The teeth or blocks being now arranged and fitted to the plate, the next step, preparatory to soldering, is to get access to the pins on the inside, for the purpose of backing them. Set the articulating model on the table with the teeth upward; .bend a strip of lead (an inch wide) outside the arch and about a half inch from the teeth ; then fill the space Avith plaster, inserting a strip of tin foil opposite the median line, so that the plaster rim will readily break at that point when removed. In a double set do the same with each half of the articu- lator. When the plaster has set, remove all wax or cement from the teeth and plate, and proceed to examine the pins, also the relations of the teeth or blocks to the plate and to each other. This temporary plaster-band We regard as essential in every case, except a few varieties of partial sets. It is equally essential in vulcanite and other forms of plastic work, as will be hereafter explained. It is a common but not good practice, where the teeth are soldered, to substitute for this tem- porary band the soldering investment. Fig. 265 will give an idea of the shape of this rim, except that, being here designed for a different purpose, it does not shoAV the im- press of the teeth. Fig. 266 represents the inner surface of a set of blocks with the wax removed, which Ave may suppose just withdrawn from the plate in preceding figure. Blocks or sections are readily replaced in their proper positions; but single teeth are sometimes so similar, especially bicuspids, that they are apt to be misplaced. To prevent such accidents, have a circular wooden block, four inches in ADJUSTMENT OF TEETH. 597 diameter, with twenty-eight cups or depressions so marked that each tooth can be instantly put into and taken from its proper cup. The teeth being thus arranged, a gold-plate, or backing large enough to cover the entire width, and from eight- to nine-tenths of the height of the posterior surface of each, is fitted to them in the following man- ner. Each tooth has securely fixed in the back part of it tAvo platina Fig. 265. Fig. 266. rivets for the purpose of connecting it to the backing. Each backing, therefore, should have two holes punched through it by means of a pair of punch-forceps, as represented in Fig. 267, large enough to admit the rivets of the teeth. After having punched one hole, a rivet Fig. 267. is inserted; then, by moving the strip of gold plate two or three times to the right and left, a mark will be left upon it, indicating the dis- tance the rivets are apart. But previously to this the rivets should be made parallel (being very careful not to strain them in the tooth), and 598 ADJUSTMENT OF TEETH. the ends filed off level. Otherwise the pins will not go into the holes punched, and there will be an uncertainty as to which side of the pin the mark on the plate corresponds. Dr. Samuel Mallet has very ingeniously invented a punch which will save much trouble in finding the proper position of the second hole. (Fig. 268.) After straightening the pins, one is placed in the Fig. 268. hole i, at the head of the punch, the other pin pressing out the mova- ble punch e (which works by the spring g), until it slips into the slot h; the two punches /, e, then make the holes at the exact distances apart to receive the pins. A simple form of punch, and one not liable to accident, is a piece of steel a half inch square "and three or four inches long." It consists of two halves riveted together at the top, each tapering nearly to a point. By turning a small screw, inserted midAvay in one leg, the points held opposite the pins are separated to their exact distance. A slight tap of the hammer marks this upon the backing, and then the holes are made with an ordinary punch. Pins often set very irregularly in a tooth ; they should be parallel, but not necessarily perpendicular. Too much bending of a pin close to the tooth makes it more liable to fract- ure in soldering, or by use in the mouth. Pins also vary much in thickness; it is better to have the pin of the punch-forceps of medium size, and to ream Avith a broach for large platina pins. A set of broaches are indispensable in backing teeth, and in many other oper- ations. The holes should be slightly countersunk on both sides, and after placing the backing on the tooth, it is made fast by splitting with a strong knife or a wedge-shaped excavator the ends of the platina rivets, or pinching them together with pliers. If the ends of the platina rivets are hammered so as completely to fill the holes in the backings, it will prevent the solder from flowing in and uniting the tAvo as firmly as it should do. The backings should be slightly hollowed before they are ADJUSTMENT OF TEETH. 599 put on; by so doing, they will fit up closely to every part of the back of the tooth. After the backings have been made fast to the teeth, they are to be accurately fitted to the plate, standing off from the plate enough for a very thin piece of watch-spring to be passed under it. This shows that the tooth is not raised, by the backing, from its place in the in- vestment. A much wider space makes the Aoav of solder uncertain ; the practice of placing scraps of gold under badly-fitted backings is a very slovenly one. Some dentists back the teeth as they grind and fit them, and before investing; others invest with the soldering mixture, and back Avithout taking them from the investment; others, again, partially invest with the soldering mixture, remove, and back the teeth, then replace, and add more plaster and asbestos or sand over the edges of the teeth. By the first tAvo methods neat or secure Avork cannot be made; the last is unsafe, because the tAvo layers of mortar are apt to separate in heating, and may displace the teeth. The most certain method, Avhich proves in the end the shortest, is that of the temporary plaster-band above described. hackings (called also stays or standards) vary much in size, shape, and thickness. Some variations are matters of taste; as, Avhether they shall be rounded, square, or beveled at the top corners; Avhether chamfered to a thin edge, or left thick, and then beveled or rounded. But other points, often considered optional, are not so, inasmuch as they affect the appearance or stability of the work. Backings Avhich cover the translucent edge of the tooth darken it by the refraction of the oxidized surface next the tooth, and Avhich cannot be kept bright; even if it could, the gold would impart a yellowish tinge. They should cover enough of the tooth, and fit so accurately, as to prevent motion of the tooth; for this Avill inevitably cause the pins, sooner or later, to break off. Backings, in relation to each other, must either be so far apart at their base that the solder will not flow from one to the other, forming a continuous band, or they must be in contact through- out Avhatever distance the solder will unite them. This rule is par- ticularly applicable to backings of single gum teeth, AA'hich are often (perhaps usually) made the full Avidth of the tooth up to the shoulder. This continuous band gives great stiffness to the plate. But the con- traction of the solder will certainly warp it, unless prevented by actual contact of the edges soldered. In case of plain teeth, a heavy, con- tinuous line of solder will almost certainly Avarp the plate. A block may be backed for soldering in one piece, or in parts closely fitted, or in distinct backings opposite each tooth. A block much curved is with difficulty backed in one piece; long or thin blocks are liable to 600 ADJUSTMENT OF TEETH. be cracked by the contraction of a backing, either in one piece or made continuous by soldering. Backings should be of the same gold as the plate, but heavier, especially if long or large. Sometimes the shape of a gum or block tooth may require the re- moval of the plaster rim, Avhich can readily be done; then replaced after the backing is completed, for the final adjustment of the teeth. The teeth are next to be fastened to the plate Avith a small quantity of cement (resin mixed with wax, or, still better, with gutta-percha and plaster), and a small roll of softened wax (not melted or made adhe- sive) placed over the entire surface to be soldered. In Fig. 269 the inner band may be taken to represent Fig. 269. the width of this wax roll, Avhich is of great service in preventing any plaster of the investment from getting acci- dentally upon the parts to be soldered. If the teeth have been previously sol- dered to the backings, this Avax strip should be narrower; but if rivets and backings are to be soldered at the same time, the rim must be made carefully to cover every point where solder is to flow. The plaster-band is then very carefully removed, and the piece surrounded with the soldering investment, Avhich must be no thicker than is sufficient to protect the teeth and hold them in place. The wax and cement are easily removed, leaving the surfaces perfectly clean and ready for the borax and solder. The investment should not project so far over the inner edge of the teeth as to obstruct the blow- pipe flame; it should not cover the lingual surface of the plate, nor should it be thick on the palatine surface. On the palatine side it would be well also to cut along the median line nearly or quite through the investment; the object of this is to give play to the lateral expan- sion of the plate, the antero-posterior expansion being usually, from the shape of the plate, sufficiently free. This we regard the simplest and best method to prevent Avarping of the plate, so often caused by the very means taken to prevent it. We have said nothing of fastening the teeth with a firm body of cement instead of Avax, so as to try them in the mouth before soldering, because a correctly taken articulation makes this unnecessary. As remarked in the chapter on articulation, this process admits of per- fect accuracy. Its very object is to prevent the necessity of any change in arrangement after teeth are adjusted. An error of articu- lation Avill often involve a change in the jointing of blocks more troublesome than the original grinding ; in fact, neatly-ground blocks ADJUSTMENT OF TEETH. 601 (or gum teeth) will not permit the slightest change of position without fresh grinding someAvhere. Trial of teeth, merely to test the correct- ness of articulation, is either unnecessary, or it is evidence of a Avant of skill. When used to test correctness in the selection of teeth, it is more excusable; for it requires experience to enable us to determine, a priori, just what style of Avork is best adapted to the case. But the awkward and momentary retention of a plate, to which the teeth are so slightly attached, is no test of its aesthetic correctness, unless the selection has been grossly misjudged. It is only after the patient has become habituated to the piece, giving time for the natural form of the lips and motions of the mouth, that we can best decide Avhether or not our Avork has beauty of expression as Avell as artistic finish. Mr. AndreAV Wilson, of Scotland, adopts the folloAving method of backing teeth: After having partially fitted the tooth to the plate, take a piece of platina foil, as thick as can be used conveniently, and, pressing it against the tooth, perforate it Avhere it is marked by the pins; then cut it into the required shape of the backing, and press it as closely as possible to the back of the tooth. Apply a little borax to the platina pins Avhich come through the back; then place the tooth Avith its face doAvnward upon a thin piece of pumice, covered Avith dry plaster, putting upon the platina sufficient gold for the thickness re- quired ; slowly heat it, gradually raising the heat until the gold melts, when it will rapidly flow over the whole platina surface, uniting so firmly Avith the pins in the tooth, that Mr. W. has never, during eight years' use, seen a case in Avhich they have loosened, even Avhere there has been sufficient violence to break the tooth. After the backing has been run, and the tooth alloAved to cool slowly, it is filed to the requisite thickness and shape ; tooth and backing are then closely fitted and finally soldered to the plate. In arranging the teeth on the plate for soldering, Mr. Wilson uses a mortar of Avhite sand and plaster equal parts, placing a thin strip of platina on the outside of the teeth, with a layer of the mortar on both sides of it, so that, should the plaster crack in soldering, the platina may keep the teeth from shifting their places. The Avhole time occupied in heating and backing a tooth is about half an hour; when several are done at once, a little longer time is required. Of course, all the backings of the set should be floAved at the same heating. Instead of using the strip of platina plate to prevent the teeth from becoming displaced, in case the plaster cracks, thin sheet iron or iron wire may be used ; but platina is undoubtedly the neatest, and has the advantage of being indestructible; it may be narroAV and thin, so that its cost would form no objection to its use. But if the plaster is not in excess, the investment will not crack. A mortar, made of three or four 602 ADJUSTMENT OF TEETH. parts of asbestos to one of plaster, will stand the hottest fire of the laboratory. Mr. Wilson's method might be improved, first, by com- pletely fitting the tooth before backing; secondly, by running the thin platina backing, one-sixteenth of an inch on the plate, to any irregula- rities of Avhich it can be quickly burnished doAvn by making several slits in the edge. This flange secures a very perfect and strong attach- ment to the plate, and is the method of backing (with heavier platina) practised in the continuous-gum work. Ordinary backings, after they have been fitted to the plate and held to the teeth by bending or splitting the pins, may be removed from the plate, set in a batter of plaster (Avith or without asbestos), and soldered; the plaster should be so stiff as not to flow over the backings. The solder should be rather harder to fuse than that used to fasten the teeth to the plate. The backings, after sloAvly cooling, should be filed, and may even be Scotch-stoned. Backings can be better and more quickly finished singly than when attached to the plate. This method, or Mr. Wil- son's, are much to be preferred to the common practice of soldering the backings to both teeth and plate at the same heating. A piece invested preparatory for soldering, and placed upon a lump of solid charcoal, is seen in Fig. 270. Fig. 270. ADJUSTMENT OF TEETH. 603 Directions for applying borax and solder have already been given. Some cut the solder into very small pieces; others use one piece to each tooth at its base, and a second for the pins unless previously soldered: in the figure the pieces are unnecessarily small. If the backings are soldered to the teeth beforehand, a more fusible grade of solder should be used at the second soldering. The work, as before stated, must be very gradually and thoroughly heated up, before directing the flame upon the plate or backings. The last point to be touched with the flame is the solder, and this not before a slight melting of the edge shows that it is just on the point of floAving. If every preparation for soldering has been properly made, the actual flowing of the solder on a full piece will take less than a minute, and will be so smooth as to re- quire no other finish than the Scotch-stone and polishing-wheels. After soldering, the cover should be placed upon the soldering-pan (Fig. 255), and the work allowed to become quite cold before removal: Avhen a charcoal (Fig. 270) lump or pumice-stone is used, the Avork must also be covered while cooling. Finishing Process.—When the piece is cold, the plaster is to be care- fully removed from the teeth ; the piece is then placed in a glass or porcelain vessel containing a mixture of equal parts of sulphuric acid and water, and heat applied. As soon as the borax (which, by the process of soldering, has lost its water of crystallization and assumed a glassy hardness) is decomposed, the vessel is removed and alloAved sloAvly to cool. This process is termed, by jeAvellers, pickling, and re- quires from ten minutes to half an hour for its completion, according to the strength of the acid and the quantity of vitrified borax on the plate. After this the acid is washed from the piece; or it is still more effectually deprived of acid by boiling in Avater containing a little caustic soda. In removing the roughness which may have been occasioned by imperfect soldering, care must be taken not to cut away too much of the plate. For this purpose scrapers, files, and lathe-burrs are used, according to the position and quantity of surplus solder. After the work has been made as smooth as possible with scrapers, etc., it should be rubbed with pieces of Scotch-stone and water until every scratch is removed; some use a fine, smooth cork attached to the lathe, and charged with water and poAvdered pumice or silex. The piece is then polished with tripoli, applied by means of oil or tallow to a brush- wheel (Fig. 271), which is made to revolve rapidly against the work. As to. the rapidity with which a lathe should be worked : drills and burrs require a sIoav movement; corundum-Avheels a quicker one; rotten-stone a rapid motion ; and whiting, zinc-white, or rouge, the most rapid of all. 604 ADJUSTMENT OF TEETH. The piece may noAV be placed in a porcelain vessel containing the following mixture : nitre, tAvo ounces, salt and alum, each, one ounce — dissolved in four ounces of water. After boiling for half an hour in this, to decompose the copper from the surface layer of the solder and plate, it is boiled a few minutes in a solution of one ounce of caustic soda in four ounces of water, to neutralize the acid, then Avashed with a brush in pure water. The removal of the copper from the surface of the plate gives to the gold the beautiful orange hue, Avhich is its natural color, and which it will retain until the friction of mastication wears off this surface. The secretions of the mouth will fail to tarnish it; and it will be free from the disagreeable taste of Avhich so many complain, who wear artificial teeth set on metallic plate. But when plate is made from coin Avithout alloy, or is of twenty carats fineness, and the solder has a corresponding quality, the pickling process may be omitted. The process of finishing is completed by polishing every part of the lingual surface of the plate, backings, and clasps with highly- tempered and finely-polished steel burnishers. They should be fre- quently rubbed on a piece of wet Castile soap, and carried backward and forward in the same direction over the plate until every part of the gold exhibits a high polish. Burnishers of different shapes are required for different parts of the work: bloodstone burnishers are also used. A piece, however, can be polished in less time, if not more perfectly, with brush-wheels. (Fig. 271.) Brush-Avheels vary in diameter, thickness, and material. Bristle-wheels vary in stiffness and length of bristle; the stiffer being used for tripoli or rotten-stone, the softer for whiting and rouge. Cotton is often substituted for bristles; buckskin or felt are also much used for wheels or circular " laps," and are especially useful in dressing up the recesses of a plate. It is of the utmost importance that wheels or laps, used for different polishing substances, should be kept entirely separate: a little tripoli or pumice powder, on a rouge-Avheel, may render useless the work of an hour. The brush should be set on the spindle of the lathe, then lightly smeared Avith suet, by holding a small piece against it while it is revolving. The rotten-stone is applied in the same manner, and with the brush thus charged, the polishing may com- mence; but the plate must not be exposed too long to the friction, as it will rapidly wear away the pure gold surface brought out by the pickle; hence some use only the burnisher or rouge after pickling. Tripoli has a sharper grit, and cuts more rapidly than the ordinary RETENTION OF PLATES. 605 rotten-stone prepared for daguerreotypists' use; but the latter gives a very smooth surface, and will, in most cases, give a sufficiently brilliant finish without rouge. A very high watch-case finish can only be given by very rapid revolution of Avheels or buffers, charged Avith the finest quality of rouge, wet with alcohol. The piece must be previously washed with soap and water, so as to remove every trace of oil. Sometimes rouge is applied on a piece of soft buckskin, Avrapped or seAved around small blunt-pointed pieces of cork or wood. The lingual surface of the plate is the only one that should be polished. The dead color of the palatine surface throws out the polish of the other side, and greatly improves the appearance of the piece. The adhesion of a plate is frequently improved by roughening the plate with a file or by engraving lines upon it. The process of finishing on a gold piece, properly soldered, is a very simple matter, and one of secondary im- portance. A piece with a Scotch-stone finish is in every respect as useful, and aesthetically as beautiful, as the most highly-polished plate. There is, however, no objection to this sort of appeal to the eye, pro- vided it is not the chief merit of the work. There are three methods adopted for the retention of dental plates, and many modifications of form required by the various circumstances of different mouths. An enumeration of all the required forms Avould be impossible in this work ; but Ave hope to represent a sufficient variety to enable the operator to decide Avhich is best for any given case. We think it far more important, however, to endeavor to explain, as far as can be done, the principles which determine these different forms and modes of retention, than to lay down any set of didactic formulas for unreasoning adoption. CHAPTER XIII. RETENTION OF BASE - PLATES — THEIR SIZE AND FORM OF OUTLINE. THE utility of a piece depends largely upon the firmness Avith which it keeps its place during mastication or in conversation. The means adopted to secure this are threefold: The first two retain the plate by extrinsic support; the last depends upon an intrinsic quality of the plate itself. 1. Spiral springs, by constant pressure, keep the plates of a double set in position. 2. Clasps, by grasping some natural tooth, hold a partial piece firmly in place. 3. The close adaptation 606 SPIRAL SPRINGS. of the plate, whether of a full or partial set, causes it to adhere with a force which is lessened, first, by the amount of air betAveen the sur- Fig. 272. faces; secondly, by the liability to displacement. These modes of reten- tion will be considered in the order named. Spiral springs, formerly very much / used, are noAV seldom employed: they are applied only to double dentures. Fig. 272 gives a correct idea of the position of the springs, their points of attachment, length, and direction of curvature. Fig. 273 represents the detached portions of the spring, consisting of standards, screws, tangs, and spiral coil. The tendency of the curved spring to Fig. 273. straighten, presses each plate upon the alveolus, acting at the points of attachment of the standards. These points are chosen, first, in the upper jaAV, as nearly as possible on the line of equipoise, Avhich will be some- where between the centres of the second bicuspid and of the first molar; secondly, in the lower jaw, where a vertical line from the upper standard meets it. Perforated bicuspids and molars are sold, adapted to such cases; and the usual plan is to attach the standards before soldering the teeth. A more accurate method is to determine the position of the standards after the pieces are finished. The presence of the teeth makes soldering of the standards more troublesome, but not impossible: they may also be riveted to the outer rim of the plate. With the diamond drill, holes can be made through the teeth, or blocks, opposite each standard. Directions for making the coil have already been given: they are usually purchased ready made. Their length must be such that the curve will not irritate the ascending ramus of the lower jaw. If too stiff, their forcible pressure will irritate the gum ; if too slight, they will fail to keep up the piece. The tangs are held in the coil by close- ness of fit; when loose, they may be tightened by floss silk. The screAvs, represented in the figure, are troublesome to make, and are very CLASPS. 607 apt to loosen. A better plan is, to pass a headed pin through standard, tang, and tooth, and rivet or solder it in the backing. This plan makes the tang permanent; the pieces are separated by detaching the upper or lower tangs from the coils. It adds greatly to the strength of the pin to pass it through the tooth or block. There should also be a shoulder on the standards, to limit the movement of the tang ; else the springs, by too great upAvard or doAvmvard motion, may irritate the mouth. It is unnecessary, in vieAV of the present limited use of springs, to describe other and very ingenious methods of attaching them. Their use is noAV confined, first, to very flatly-arched upper jaAvs, usually small, covered with hard membrane, and having the attach- ment of the facial muscles close to, or quite upon, the ridge; also to lower cases, Avhere all trace of the ridge is gone. Secondly, to pieces inserted so soon after extraction that the rapid absorption will quickly destroy the adaptation. Wre shall speak elsewhere of other means adopted to meet these exigencies; in failure of Avhich, spiral springs are to be used. But they are troublesome to make, annoying to Avear, difficult to keep clean, and liable to accident; hence Ave only use them as a last resort. In conclusion, it should be noticed that the upper plate of spiral-spring pieces does not cover the palate, but is shaped more like the loAver piece. This is one of its compensating advantages ; for it is an objection to the othenvise valuable principle of atmospheric pressure that it covers so large a portion of the mucous surface. clasps. This method of retention, necessarily applicable only to partial pieces, has fallen into much disfavor, and ghren place to methods, in lieu thereof, Avhich are really more objectionable. But, like many other time-honored practices which modern dentistry has thrown in its Avaste- basket, there are very decided advantages in this mode of retention, Avhich make it, in certain cases, the best possible one. The disuse of clasps has groAvn out of, first, their injurious effects, due to improper construction and injudicious application; secondly, the difficulties of making a clasp-piece. W'e venture the assertion, that one-half the dentists do not really know how to make a perfectly adapted clasp- piece; and that, of the remaining half, two-thirds will not take the trouble. The tediousness of clasp adjustment is out of place in that rapidity of manipulation demanded by the cheapness of modern den- tistry. Nor can Ave expect to see the easily made, but ineffectual, vacuum cavity give place, in turn, to the clasp attachment, which it has to such an extent stiperseded, until the profession becomes awakened to the necessity of substituting good work for fast Avork — economical high-priced work for expensive low-priced work; until the mechanician 608 CLASPS. so far respects himself as to value his labor more than the cost of his materials, and ceases to use certain substances because they are cheap, rather than others because they are better. • Next to pivoting, the clasp is the most secure of all methods of attaching artificial teeth in partial cases. But it is not universally ap- plicable for reasons hereafter stated. In deciding upon the propriety ■„ of using clasps, the remaining teeth must be carefully examined, to determine whether, in shape, position, texture, and relation to other teeth and to the proposed plates, there are any which admit of being clasped. If there are such teeth, a perfect impression of them is necessary; then greatest accuracy in fitting the clasp; lastly, a most exact adjustment of this to the plate, to which it is to be fastened with great care. Scrupulous observance of these points, in connection with a properly fitted and shaped plate, will take from clasp work the force of the objections urged against it. In the selection of teeth to be clasped, the points for consideration are: 1. Their condition : never clasp loose teeth, or those Avhere there is much alveolar absorption; or, if possible to avoid it, those which have filed surfaces. 2. Their shape : avoid all conical teeth, such as third molars and canines; also teeth considerably larger at the grind- ing surface than at the gum. The proper shape for clasping is the cylinder, or rounded prism; and only so much, or such part, of any tooth should be clasped as has this shape. Hence it is that thick narrow clasps are best, because few teeth have much breadth of cylin- drical shape. 3. Their position : incisors, canines, and third molars must be rejected for this reason; and second molars are unfit, if the plate holds incisor teeth. The incisors and cuspids are, of all the teeth, least suited for the attachment of a clasp. It is exceedingly difficult to apply clasps to these teeth in such a manner as to retain even a single tooth with sufficient stability to be worn with any degree of comfort. We remember once to have seen a case in which a central incisor (natural tooth) was inserted and kept in place by a gold wire projecting from each side of the. tooth into holes drilled into the adjoin- ing teeth. A stage of dental progress that permitted such a process, might also have allowed the clasping of incisors; but we know of no possible circumstances that will justify, in the present state of dental art, the clasping of any of the six front teeth. No lower teeth should be clasped ; but in some cases a stay (half-clasp) may be used. The best teeth, in respect of position, are the second bicuspids; next, the first molars; thirdly, the first bicuspids; and, lastly, the second molars. These eight teeth are the only ones that should ever be clasped; and, if possible, the choice should be confined to the first four. 4. Their relation to the plate and to the other teeth. Let the clasped tooth be clasps. 609 as near the line of equipoise as is consistent Avith other considerations. For incisors alone we should, for this reason, give preference to the first over the second bicuspids; and, in case of the loss of the ten or twelve anterior teeth, we should use no clasp on the remaining molars. Teeth not decayed should never be separated from others, with which they are in contact, for the purpose of passing a clasp. If no other tooth can be found, a stay (half-clasp) must suffice. Observance of the conditions above enumerated restrict very much the range of cases that admit of clasps. In the matter of position and relation to the plate, circumstances may compel a choice not the most favorable to success ; but, in other respects, it is far better to dis- pense with clasps than to apply them so as to incur risk of failure or injury to good teeth. The liability of the tooth to decay, around which a clasp is applied, is always greatly increased by the removal of any portion of its enamel. The application of clasps to diseased or loose teeth always aggra- vates the morbid condition of the parts, and causes the substitute, Avhich they keep in place, to become a source of annoyance to the patient. Besides, such teeth can be retained in the mouth only for a short time, and when they give way, the artificial appliance becomes comparatively or entirely useless ; and even before their loss, it is not held firmly in its place. Its instability exposes its presence to the observation of the most careless observer, and this motion is injurious to all the teeth near or against which the piece comes. In the lower jaw, parts of sets are much less frequently called for than in the upper, and when they are, the use of clasps may be dispensed Avith alto- gether. A clasp can seldom be applied advantageously to a lower molar. The loAver front teeth are least liable to decay of any in the mouth, and therefore do not require replacement, except in full sets, unless lost by a blow or by the destructive action of salivary calculus. A partial lower front piece calls for half-clasps or stays; but other partial lower pieces (replacing bicuspids and molars) should not depend for their stability upon any remaining bicuspid or cuspid. If the injurious effects liable to result from the application of clasps to teeth, selected according to the rules given, could not in any Avay be counteracted, dental substitutes retained in the mouth by this means would, in the majority of cases, be productive of more injury than benefit; but they may be in great measure prevented. They are not caused, as many have erroneously supposed, solely by the mechanical action of the clasps upon the teeth, but also by the chemical action of the secretions of the mouth and decomposing particles of food. The method of measurably preventing these deleterious effects is twofold : First, to prevent the chemical action, the removal of the artificial 39 610 CLASPS. teeth, and thorough cleansing of them and the natural organs; this should be done every night and morning, and the teeth rubbed with a brush and waxed floss silk until every particle of clammy, vitiated mucus and foreign matter is removed. The inner surface of the clasps should be freed from all impurities, and the whole piece cleansed with a brush and water. Secondly, to prevent or lessen the mechanical action, the clasp should, as before remarked, fit with great accuracy the parts of the tooth protected Avith hard enamel; the whole piece should have such closeness of adaptation as to prevent motion of the clasp upon the tooth. We have elsewhere spoken of other injurious consequences of clasps placed too near the gums or exposed necks. Rapid decay and breaking off of the teeth, inflammation of the gums, of the alveolo-dental periosteum, destruction of the alveoli, and loosen- ing of the teeth, are among the common results of the clasping of teeth as it is too often practised. Consequences such as these have led many to an unqualified condemnation of this method ; yet, as we have said, when suitable teeth are selected for clasping, and the work is properly executed, it is the best.and most durable way in which a partial piece can be secured. Shaping and Adjusting Clasps. — The gold employed for clasps should be about one-third or one-half thicker than the plate, and as wide as the cylindrical portion of the croAvns of the teeth to be fitted. Some clasps are best made of half-round wire, and narroAV; others may be broader and thinner: thick narrow clasps are more universally applicable. In quality, it is better that clasp and plate be the s"ame; except when the plate is of pure coin. In this case, add copper (but no silver), to give elasticity. Platina, often used for this purpose, imparts too much brittleness, after the piece has been worn for some time. Some may fit the tooth close to the gum; but in other cases, the shape of the tooth, absorption of the alveolus, or morbid sensitive- ness of the neck, forbid this. Enamel surfaces best resist the wearing action of clasps; dentine, exposed by the file or chisel, is more liable to abrasion or decay; cementum should in no case be brought in con- tact with clasp or plate. If the clasps chafe against sensitive parts, inflammation of the alveolo-dental membrane may be set up, followed by wasting of their sockets, and ultimate loss of the teeth. With the plate in position in the mouth, a wax impression may be taken; the plate, adhering to it, on being withdraAvn, will have a cor- rect relation to the teeth which are to be clasped. Others adopt the less accurate method of adjusting the plate to the original plaster model. But as, for reasons before given, it is advisable to cut off the teeth from the model used in moulding, a second model is necessary, and usually for this purpose a second impression. Moreover, if the CLASPS. 611 mouth has marked irregularities, or rugae, and the plate covers much surface, it cannot be fitted upon a plaster model so as to hold the same precise relation to the teeth as when in the mouth. When accurately fitted, they may be at once soldered on the model, or may be attached to the plate by means of a small piece of wax or cement composed of one part wax and two of resin ; this should be softened, and applied to the plate and to the inner side of each clasp. The plate and clasps thus united are carefully removed from the plas- ter model, and laid Avith the convex side doAvnward on a piece of paper. Plaster is then poured on the upper side of the plate, covering it and the clasps to the thickness of half an inch. After this has set, the piece may be taken from the paper, placed on charcoal, the Avax being softened and removed, and prepared for soldering. This is the simplest Avay of fitting clasps to the plate and preparing the piece for soldering; but Avhen the clasp-teeth deviate from a verti- cal position, or Avhen the teeth are of such a shape that the Avax im- pression does not copy them accurately, this method is, in such cases, not reliable. The clasps must be fitted to the teeth in the mouth, instead of on the plaster model, and may then be attached to the plate as just directed. Often only one can be attached at a time, and after this has been soldered, the piece is replaced in the mouth, and the other made fast to the plate. The greatest care is necessary to prevent altering the position of the clasp in taking the piece from the mouth. The folloAving is Dr. Fogle's method for securing accurate adaptation of the clasps. They are first fitted to the plaster model, leaving the ends straight. A narroAV strip of plate, about five-eighths of an inch in length, is used as a temporary fastening, one end of Avhich is sol- dered to the lingual surface of the clasp ; the plate and clasp are now both placed on the model, (made from impression taken Avhile the plate 3296 612 CLASPS. is in the mouth,) and the other end fitted and soldered to the plate, forming a sort of semicircle or bow. Fig. 274 represents the plate, clasps, and temporary fastenings on the plaster model. In Fig. 275, they are seen separate from the model. The clasps are now adjusted to the model: however accurately this is done, it will be found, on applying the plate to the mouth, that they will not fit the teeth there. After properly adjusting them, the tem- porary fastenings Avill be found sufficient to hold the clasps in their exact position while the piece is being removed. This done, it may be invested in plaster, placed on charcoal, and the other steps connected with the process of permanent soldering gone through Avith; detach- ing the temporary fastenings when the plaster has fixed the clasps in position. Dr. Cushman advises, in very difficult cases of adjustment, as where the clasp-teeth are much inclined, and where you have to fasten to sec- ond molars, a slight modification of this plan. After soldering one end of the strip to the clasp, and having bent the other to touch the plate when on the model, put both in their proper place in the mouth; then, with a sharp-pointed instrument, indicate the point where the bow touches the plate; place them on the model again ; adjust the end of the bow to the point marked ; confine it there, and solder fast. Dr. Cush- man considers Dr. Fogle's method of adjusting clasps so valuable that he never ventures to set clasps permanently, even in the simplest case, upon the original model, with the plaster teeth as the only guide for position. Dr. Lester Noble's method is as follows: Place the plate in the mouth, and let the clasp bind upon the tooth with only sufficient firm- ness to keep it in its proper place. Then mix a small quantity of plas- ter from a lot which, by previous trial, you find requires four or five minutes to set; put it upon a piece of paper or sheet lead about an inch square, and, just before it begins to harden, introduce it into the mouth upon the forefinger, pressing it into gentle contact with a portion of the plate and about one-half of the clasp. It must be held there for three or four minutes, until it is sufficiently hard to break with a sharp fracture; this point you can determine by examining the plaster left in your bowl. The plaster must then be AvithdraAvn. Sometimes plate, clasp, and plaster will be brought away together; or the plaster and clasp together leaving the plate; or the plaster will separate, leaving both clasp and plate in the mouth. Should the plaster by any acci- dent break, it can readily be united at the point of the fracture, with- out in the least altering its shape — one great advantage over wax. If the plaster adheres to the plate on withdraAval from the mouth, it must then be carefully detached, the plate replaced, and the same process , CLASPS. 613 repeated for the second clasp; or possibly the impressions for both clasps can be taken at once. Several precautions are necessary. If the clasp bind too tightly around the tooth, its ends will, when removed, spring together ; and thus it will not exactly fill the original impression made in the plaster. If the part of the clasp which you design to cover with plaster be so regular in shape as to make its adjustment, Avhen out of the mouth, uncertain, mark it Avith a file or by a small point of solder; this will be copied in the plaster, and remove all doubt as to its definite posi- tion. If the plaster be extended over some part of the edge of the plate, it will, in the absence of any marked irregularities of surface, give a better guide for its readaptation. Lastly, if the plaster cover too much of the clasp-tooth, it will be more liable to break on being vvithdraAvn. Take noAV the clasps, place them each in their separate impressions in the pieces of plaster, securing them if necessary by a small piece of softened wax. Place one end of your plate in. its corresponding bed in one of the plaster pieces. If proper care has been used, both clasp and plate will fit into the plaster with unerring accuracy, and of course hold the precise relation as Avhen in the mouth. While in this position, cover the clasp and the under surface of the plate with fresh plaster, or plaster and sand; when this has hardened, remove the first plaster, just as in other cases you would remove the wax, preparatory to sol- dering. The methods of Drs. Fogle and Noble may be thought too tedious for cases Avhere the shape and position of the teeth are such that a wax impression will accurately copy them; but in the great majority of cases it will be found essential, to accurate adjustment, to resort to one or other of them. If the clasp stands off from the tooth on its coronal edge, the food is apt to pack into the wedge-shaped space and loosen it, or even change its shape; if on the edge near the gum, it gives lodgment to the food and mucous secretions, to the injury of the tooth. Dr. Spald- ing recommends, as a preventive against such lodgment, to use in all cases thick narrow clasps; to attach them by two or more standards (Fig. 276), if the clasp is long; to put them well up on long teeth, and on short teeth, to cut aAvay the plate. In this Avay most of the neck is exposed to the cleansing action of the tongue. The close adaptation of the clasp to the surface of the tooth is too 614 CLASPS. often neglected. It is commonly done with round pliers, making trial from time to time upon the tooth of the model. This is an uncertain method in any case, and in many utterly worthless. Prof. Austen advises always to take a separate plaster impression of the teeth to be clasped; for Avhich purpose a small cup of wax, lead, or tin foil is used, one-eighth inch larger than the tooth. Let the plaster get quite hard; then slightly open the impression; withdraw it, and close up the fissure. Make from this either a plaster or a.fusible-metal tooth; if the former, harden it with soluble glass. With round pliers and a hammer, clasps can be fitted with great exactness to such a metallic tooth. Extreme accuracy of fit may most easily be obtained when the contour of the tooth is irregular, by the following method: burnish down to the tooth a strip of very thin platina; then on the outside of this strip lay pieces of gold (of the fineness suitable for clasps), with borax, and flow them with the blow-pipe. A common error in soldering clasps is to make their union to the plates too Avide. Clasps are often called springs, but if soldered through nearly their whole length, they become rigid stays, devoid of elasticity. There should always be a proportion between the size of the clasp and the width of its attachment; in no case should it exceed three-sixteenths of an inch, and one-eighth inch is ample for most cases. When practicable, the two arms of a clasp should be of equal length ; but in short clasps it is sometimes preferable to throw all the elasticity into a single arm. A single attachment is better than two, as it gives more play to the arms of the clasp in the slight unavoid- able motions of the plate. Again, in shaping the plate, cut it Avell off from the tooth, allowing a tapering tongue to extend up to the clasp, for its attachment. In clasp-pieces and in all partial pieces, remember that the plate should come in contact Avith teeth it approaches, or else stand as far off as the case will permit; the narroAV band of gum, .so often left between plate and teeth, is liable to irritation by compression between the two ; this is productive of more annoyance and injury than the direct contact of the plate against the tooth. Partial Clasps or Stays. — These differ from clasps in the absence of elastic arms grasping the tooth. Taking a short, rounded prism (tri- angular in case of bicuspids, in molars, quadrangular) as the "type" of a clasped tooth, the clasp proper must grasp a side and tAvo angles or tAvo sides and three angles. If it lies against two sides and one angle, or if two opposite sides are so inclined (in the line of the clasp) that it Avill not take hold, then it becomes merely a stay. Stays demand for serviceable action a point d'appui; hence they must be in pairs —lying either against the tAvo teeth bounding an in- terdental space, or against teeth on opposite sides of the mouth. They CLASPS. 615 have great value in all partial cases where there are no isolated teeth suitable for clasps. Their function is to give stability to the plate by preventing lateral motion. When the bicuspids or molars have inclined or bulging inner surfaces, the stays hold the piece after the manner of a clasp; the elastic force being given by the plate. This result can only be obtained, however, by a very carefully taken plaster im- pression Avhen a vulcanite plate is made; or, in case of gold plate, by getting the exact relation of the parts by Dr. Noble's method. It is a mistake to attempt forcible retention of a plate by the lateral thrust of stays; any such pressure causes the teeth to yield, and then the stays can only act as in the cases first given. It will be observed that, when the stay on each side is double, as in Fig. 277, it not only prevents lateral motion, but the points between the teeth prevent back- Avard motion. The stability given in this manner by stays, taken with an exact adaptation of the plate, is far more trustworthy than that given by any form of vacuum cavity. In connection with clasps, we shall briefly notice two methods occa- sionally practised for the retention of plates. First, by the pressure of wood against the tooth. This method Avas formerly much used, when human or ivory teeth Avere set on bone. Stays Avere carved in bone (see Fig. 277) ; or metallic stays, or clasps, were riveted, or grooves and cavities Avere cut, holding slips of some hard Avood which pressed against the teeth. This method was applied by Dr. Stokes to metallic plates — soldering gold tubes to the plate near the teeth, so that the end of the inserted Avooden pivot, slightly projecting, pressed on each side of the tooth selected. Secondly, by drilling into one or two sound roots of incisors, canines, or bicuspids, a short canal, and lining it with a gold tube. Correspond- ing pins, soldered to the plate, keep it in place much as stays do ; if the roots permit deep canals, they may retain it with considerable force. Such a pin may be used in combination Avith a clasp or stay. Directions given in chapter on pivot teeth easily explain Iioav to prepare and attach such pins. In some cases it may be desirable to use such a pin in place of clasp or stay; but the plate must cover enough mucous surface to give stability. We question the propriety of subjecting the roots of two incisors to the strain of five or six teeth on a plate of this kind. Size and Outline Form of Special Cases.—It is impossible to enumerate 616 FORM OF CLASP-PIECES. all varieties of clasp-pieces, nor could we delineate under each variety any one form as absolutely best for all its sub-varieties. The more philosophical course is to find, if possible, what principles, mechanical and physiological, determine the best form in any case, and to illus- trate, by a few examples, the application of these principles. Upper Incisors.—The plate must not cover the front of the alveolus, so that, on front or side views of the mouth, its presence can be de- tected. This rule applies also to canines and front edges of bicuspids. The model at these points should be scraped so that the corresponding die shall give a shape Avhich will sink into the gum. The plate must also be filed to a thin edge before grinding the tooth. With these precautions, a tooth or block may have the support of the plate under the centre of its base. Otherwise, it becomes necessary to cut the plate along the line of the backings; and this is, in some cases, the best plan. Incisor teeth, if firmly bedded in the gum, may trust for stability to their hold in the standards, provided they have been pro- perly fitted and soldered. The size and shape of plate between teeth and clasps will depend upon the number of incisors, position of clasps, presence or absence of other teeth, and upon peculiarities of the mouth or of the patient. For the application of the principles already given, to these several condi- tions, we shall select a few particular cases. One Incisor. — A central or lateral may be clasped to a first molar on the same side by a plate clasped, as in Fig. 278, fitting closely against the intervening teeth, or by a plate, as in Fig. 279. When three or more natural teeth intervene between the clasp and artificial teeth, the latter form is preferable, because there is no possibility of irritating the teeth by the plate or by mucous deposits. It will be noticed that the curve of the plate is opposite that of the den- tal arch, thus giving proximity to the teeth only where it is unavoidable. A lateral incisor, cuspid, or bicus- pid may be applied in the same way; and if the second bicuspid or first molar is unfit, from its shape or from decay, to be clasped, the plate may be extended to the second molar, or it may be even carried across the mouth, and clasped to a plate on the opposite side; but these modifications are suggested only in cases of necessity. Such plates may be made very narrow, if strength is given by increased thickness; but too narrow plates are open to the objection of allowing the Fig. 278. FORM OF CLASP-PIECES. 617 attached tooth to bed itself too deeply under the pressure of mastica- tion. When the form in Fig. 278 is adopted, it is usual to direct soldering a Avire or band along the festooned edge, to give strength. A much better plan is to gain strength by thickness of plate, and to chamfer the plate along this edge. The thin edge protects the gum equally well, does not wear the teeth more than the thick one, and has the decided advan- tage of giving no space for lodgment of food. This plate Avill permit attachment of clasp to the molar or to either of the bicuspids, accordingly as one or other of these may be best for clasping. Decision in this case is based on principles which apply to many other cases. Supposing the three teeth well shaped and sound, the molar is firmly implanted by its trifid root, and permits com- plete encircling with the clasp; but it is farther from the incisor; hence there is more strain upon tooth and clasp. With the clasp to the second bicuspid, the plate having the same length as before, Ave have the best possible application of its retentive power; it cannot, however, pass around the outside or front angle of either bicuspid, consequently the clasp does not have so firm a hold on the tooth. The same remarks apply with even more force to the first bicuspid. There Avill usually be some modifying circumstances to determine, in this class of cases, choice of the clasp-tooth. Tim or Four Incisors. — Two incisors maybe attached to a plate shaped as for one (Fig. 278), with the addition of a second clasp, when the teeth permit. But much the best practice is to select the second tooth on the opposite side. Fig. 280 gives the form Avhen it is decided to run the plate up to the intervening teeth. Fig. 281 represents the se- cond form, better suited than the first in certain cases of two in- cisors. With four incisors and clasps on second bicuspids, the first form is best, because only tAvo teeth lie betAveen the incisors and clasp; and it is better to carry the plate up to the teeth than to expose so small a portion of gum. For four teeth, the plate should be rather wider than for tAvo. In these cases, a closely-fitting plate assists so much in its OAvn reten- tion, that bicuspid stays will often suffice to retain them, or a clasp on 618 FORM OF CLASP-PIECES. one side and a stay on the other. When the adhesion of the plate to the gum is thus partly relied upon, it is not necessary to make the plate for four incisors larger than in Fig. 280. When the patient is very in- tolerant of the presence of much metal in the mouth, two teeth may sometimes be securely in- serted, as suggested by Dr. May- nard, upon a T-shaped plate— the cross - piece, one - fourth to three-eighths of an inch Avide, fitting the arch from bicuspid to bicus- pid; the slip to which the tooth is attached being soldered to the centre, and also fitting the arch. Such a piece, well made, will resist considerable traction upon the incisor. Owing to the peculiarity of its shape, the attempt to draAV down the tooth springs the transverse slip of metal, and causes it to bind upon the bicuspids. When the four incisors and the cuspids are to be replaced, the con- struction of the plate (Fig. 280) is upon precisely the same principle as the preceding, the only difference being that the plate should be rather larger. When the teeth on one side of the mouth are too much decayed, or are incapable of affording a secure attachment, or are missing, even this number of teeth may be held by one clasp on one side of the mouth and a stay on the other. But the plate should be extended half or three- fourths of an inch back of the tooth to which it is clasped. If this precaution is neglected, the piece, from its Aveight, may act as a lever upon the tooth, and loosen it or cause periostitis. It sometimes hap- pens that a piece made originally with clasps on both sides of the mouth loses the benefit of one clasp from the loss of the tooth; and yet the patient retains it in place as well as before. The piece is then, in part, retained by the fit of the plate to the gum ; from which We learn that if only one clasp can be attached to a plate with from four to six teeth, it is advisable to cover rather more of the surface of the mouth. In this combination the clasp and stay give steadiness, and the close fit of the plate to the gum gives adhesion. Upper Bicuspids. — One or both bicuspids on one side are often at- tached to a plate about the size of a cent, clasped to the bicuspid or FORM OF CLASP-PIECES. 619 molar behind. But such pieces are not of much service in mastication. It is better practice to leave such a space unfilled, than endanger the durability of a good tooth by clasping it. If there is a bicuspid space on either side, the plate crosses the mouth. Fig. 283 represents such a plate clasped to the first molar and fitted, as is very commonly done, closely to the incisors. But in this and all other cases where the four or six front teeth remain, it is decidedly better to leave as large a space between the plate and the teeth as possible. The strength of the plate is preserved by giving less curve to the back edge, or by doubling the plate in the middle. The design of this form is not merely to keep the plate from the front teeth, but to leave uncovered the part of the mouth immediately behind the incisors. Two important points are gained by this. The sense of taste is more impaired by covering this part of the palatine surface than any other — not because fibres of the gustatory nerve have any special distribution here, but because of the universal habit of puess- ing the tip of the tongue here, in the act of tasting; and pressure against the natural mucous surface develops this sense most fully. Secondly, the~ articulation of the dental letters (the mutes T, D, Th, the nasal N and the liquid L) is thickened by a plate covering this part. Such covering is in many plates necessary; but it is Avell to avoid it, for the above assigned reasons, Avhenever possible. When the loss of bicuspids is accompanied by that of the six front teeth, and the first molars alone re- main, a good form of plate is shown in Fig. 284. The backAvard exten- sion of the plate, curving partly over the alveolus, is designed to prevent the weight of the piece from acting injuriously on the mo- lars, and to assist their retentive poAver. If the second molars are also in the mouth, the extended plate must be differently shaped.* * The festooned shape of this and similar cuts is designed to mark the number and position of the artificial teeth. The forms of the teeth are omitted, as having nothing to do with the subject of this chapter. The plates on the models are token from the valuable work of Prof. Richardson. 620 FORM OF CLASP-PIECES. If the molars are well shaped and firm, the plate may be narrower than here represented, being careful to make it thicker also. But if the presence of adjacent molars prevents the use of complete clasps, or if their form renders stays necessary instead of clasps, the plate may be rather wider. Be careful, however, not to cover the hard floor of the palate, or to attempt giving, by a cross-band at the back of the plate, the stiffness which is best gained by thickness of metal. Plates of this class are kept in place as much by the adhesion of con- tact with the gum as by the clasps. In many cases the force of adhe- sion is such, that the lateral support of stays is quite as effectual as clasps. Hence, after a clasp-piece of this kind has been worn for some time and become perfectly set to the mouth, it may be advisable to shorten the clasps into stays; indeed, it is better practice, in all cases, to anticipate this ultimate fit of these plates, and make stays at first instead of clasps. This applies with still more force to the loss of twelve teeth, the second molars remaining, which should in no case be clasped; stays may very properly be used to prevent lateral or backward motion of the plate. The presence of these second molars, by giving lateral steadiness to the plate, prevents all necessity for covering the hard palate, and makes a vacuum cavity wholly uncalled for. A soli- tary molar should never be clasped, nor should it be allowed to remain in the mouth. Alternate Spaces. — It remains to consider the forms of plates for vacancies alternating Avith natural teeth. The forms given for four incisors will answer for all alternating vacancies anterior to the second bicuspids, remembering to make the plate wider in proportion to the number of teeth, and thicker in proportion as it is made narrow; also, that a first bicuspid may, in many of these cases, be clasped Avith better effect than a second, or than the first molar. Fig. 285 is a good type for Fig. 285. Fig. 286. cases where the vacancies include the bicuspids; notice in this cut the backAvard extension of the plate. Where the natural teeth are in FORM OF CLASP-PIECES. 621 groups of two, it is best to carry the plate close up; if as many as three or four are together, the plate may be cut away, especially if they are incisors. Fig. 286 represents an exceptional case, in which two laterals and two left bicuspids are attached, by clasping, to the right first bicuspid and molar. The left molars are supposed to be loose, or sockets much absorbed, or from some other cause forbidding clasps or stays. In this case, the undue strain on the clasp-teeth will ultimately cause their loss. Whenever an unavoidable strain of this kind is thrown upon a tooth, a clasp may be used in preference to cov- ering the palate, provided the patient is content, for the sake of the firmness which it gives, to risk the loss of the tooth. Teeth are more firmly retained by clasps than by atmospheric pressure, and this, Avith many patients, outweighs all considerations of injury to the other teeth. Partial pieces, with alternating spaces, do not acquire that adhesion by contact found in cases where the lost teeth lie together. The inter- rupted margin between the teeth so readily admits air under the plate, on the slightest motion, that the atmospheric pressure is imperfectly applied. Hence there is continued demand for the retentive power of the clasps. The vacuum cavity does not correct this difficulty, or supply the place of clasps, since, as will be explained in the next section, the vacuum acts on soft membrane and has necessarily a tem- porary force. When the six or eight front teeth remain, a plate holding bicuspids and molars cannot be retained by clasps. In the first case the cuspids could not be clasped, nor would it be proper even to carry stays against them. In the latter case, the weight and leverage of the piece would be too great for the slight clasp that a first bicuspid permits; but two stays, Avith the points passing as far to the front of the bicuspids as the cuspids allow, would tend to prevent the slipping of the plate back- Avard. Lower Partial Pieces. — These do not properly come under the head of clasp work. In replacing one or more incisors, lost by accident or salivary calculus, half-clasps may be applied to the bicuspids. For such cases the best style of Avork, beyond all question, is a vulcanite plate, made on a model from a plaster impression. Fitting with great accuracy the inner surfaces of the bicuspids, it is firmly held Avithout injury to the retaining teeth. Partial pieces filling bicuspid and molar vacancies should not clasp cuspids or bicuspids ; the position of re- maining molars seldom permits clasping, even stays cannot always be applied. In chapter fourth, on preparatory treatment of the mouth, the ques- tion of extracting molar or bicuspid teeth, Avhich might otherwise be used for clasping, is considered. The importance of permanence of 622 ATMOSPHERIC PRESSURE. the work outweighs any temporary advantage resulting from clasping one or two such teeth. In chapter third, and in the section on reten- tion by clasps, are many remarks which it is unnecessary to repeat, out which are important for the full understanding of the details of construction given in this section. PLATES RETAINED BY ATMOSPHERIC PRESSURE. Of the two methods of retaining a dental appliance, already con- sidered, the first, by springs, is suited only to entire dentures; the second, by clasps, is adapted only to partial cases. The principle of retention now to be considered is applicable to both: Avhere practicable, it is the most perfect way of retaining a set of artificial teeth. If the pressure of the atmosphere could be removed from the mucous side of a plate, allowing its full force to be exerted upon the lingual surface,' the smallest plates would adhere with a force of four pounds, the largest, forty. But, for reasons to be given, plates seldom have one- fourth of this resistance to displacement. There are two methods in present use for securing the service of atmospheric pressure. One is by close adaptation of the plate; the other, by construction of a cavity of definite form. Both act by the more or less perfect exclusion of air from between the plate and the mouth. The first will be con- sidered as the Adhesion of Contact; the second as the poAver of the Vacuum Cavity. Before describing the separate application of these to dental plates, a few remarks are necessary, in addition to what has already been said in the last section of the third chapter, in exposition of the general principles of atmospheric pressure. The surfaces of two pieces of highly polished ground-glass, if pressed together, will adhere firmly; so much so, sometimes, as to resist every attempt at separation. Surfaces less smooth and close-grained will also adhere with great tenacity, if their pores or irregularities are filled by wetting with water. If both surfaces are rigid, they may be made to slide upon each other, but will resist a force of five to fifteen pounds for every square inch, if applied at right angles to the surface; if one surface is soft and pliant, it becomes difficult to keep it in con- tact around the edges. Traction upon the centre, as in the case of a disc of wet leather upon a flat stone, will draAV in the edges, and create a vacuum in the centre. It might be supposed that in this vacuum space lies the power that raises the stone; whereas, it lessens the power by reducing the area of stone in contact Avith the leather, even if the vacuum is perfect. Still, if the entire circumference is in contact, no air enters the cavity, except what passes through the porous leather, and for a time the lifting poAver of the disc is sufficient to raise the stone. If traction be made upon the disc anywhere but in ATMOSPHERIC PRESSURE. 623 the centre, the flexible edge will be raised, air enters between the sur- faces, and counteracts that pressure on the under side of the stone Avhich Avas the lifting force. Hence, between two surfaces adhering by simple contact, one of Avhich is soft and pliant, adhesion is not so persistent as where both are rigid, because of the liability to separation around the edges admitting air between the surfaces. Applying this to dental plates, Ave may understand their liability to become detached by a degree of motion which separates them from the gum at any one point around the edge. We learn, also, that so long as absolute contact is main- tained, we have the most perfect exclusion of air practicable; hence, no force of adhesion in a limited vacuum cavity (the perfect exhaus- tion of which, is impossible) is comparable to the adhesion of the entire » surface of the plate, provided this is made as perfect as possible by accurate workmanship, and is not weakened by the admission of air around the edges. If we exhaust the air from the barrel of a key, and apply the lip, it will be drawn in, and held with a force sufficient to support the weight of the key for some time. This simple experiment will prove on examination very instructhre. The mucous and submucous tissues are pressed into the key, because the fluids pervading these parts, being under pressure in every other direction, tend toward the point from which the pressure is wholly or partially removed. The extent to Avhich the lip is drawn into the key will depend upon two conditions. First, the softness and mobility of the tissue; secondly, the shape of the edge of the orifice. If, in addition to these two points, we inquire, thirdly, why the key, after a time, drops off, we shall from this simple illustration have fully explained the rationale of the vacuum cavity, as applied for the retention of a piece of dental mechanism. First: the extent to which, or rapidity with which, a partial vacuum becomes filled up by any yielding tissue with which it is brought in contact depends upon the mobility of its structure. We say, partial vacuum, because the process of mechanical exhaustion can never pro- duce a perfect vacuum. If the Avater Avhich gives softness to mucous tissues was perfectly free to move, the cavity would be instantly filled, hoAvever deep. Parts as mobile as the tongue and lips yield readily to this fluid pressure; but the mucous membrane of the alveolar ridge and palate being more or less tied down to the bone, fills the cavity more slowly; if too deep, it will not fill it at all, except by hyper- trophy. Reverting to the experiment of the key: if violent suction is made, a purple spot is left upon the lip; the mucous tissues being pre- vented by their structure from filling the vacuum, the fluids still feel the impulse of atmospheric pressure: the blood, thus impelled with a 624 ATMOSPHERIC PRESSURE. force which the thin capillary walls cannot resist, is extravasated, as takes place also in the application of " dry cups." Hence, where a dental-plate cavity is so deep that the tissues cannot fill it; if the degree of exhaustion is such as still to draw upon the surface, the tissues are in danger of being ruptured. Such a source of irritation will, in many persons* develop morbid action, and should forbid the use of deep cavities in any plate. Secondly: the shape of the edge modifies the rapidity with which the cavity fills. If the edge of a cupping-glass is rounded, the skin glides under it, and is drawn from the adjoining parts into the glass; but if the glass is ground so as to present a sharp edge on the inside, this beds itself in the surface, and prevents so much of the adjacent skin from being drawn in. It rises to a less height in the cup, and the remaining force of the vacuum is spent upon the capillary vessels, t which are ruptured. Hence, we learn that sharp-edged cavities fill less rapidly, but act with more powTer upon the tissues; they are con- sequently more apt to excite disease, if the cavity has sufficient depth to allow continued action. Thirdly: as to the cause of the final dropping off of the key: Avater, and all the moist tissues of the body, contain atmospheric air, which they yield up under a vacuum. Hence, a mucous membrane, although, at first drawn strongly into a cavity, will make the vacuum less com- plete, by giving out the air contained in its tissue and in the blood, constantly circulating through it. The adhesion of a vacuum, there- fore, over mucous membranes, requires reneAval by occasional suction; since the blood is constantly circulating through the surface, and sup- plies air to the cavity. Mucous membranes have also the property of absorbing air; as is seen in the lining of the bronchial cells constantly, and in the power of the mucous membrane of the intestines to absorb the gases there generated. This property acts an important part in absorbing small quantities of air unavoidably caught between the plate and the mouth ; thus partly explaining the well-known fact, that plates adhering by simple contact become tighter after being worn aAvhile. Thus the double action of mucous membrane, absorbing minute por- tions of air pressed against it, and giving out its contained air to a vacuum, favors the retention of simple contact, whilst it acts against the efficacy of the vacuum. In either case it prevents the full force of pressure, theoretically possible. The practical inference from the lesson of the key is, that the Vacuum Cavity acts well at first, and may be useful for the temporary purpose of retaining a plate, until the changes of which the mouth is capable adapt it more perfectly to the plate; but for permanent adhesion, the only reliable application ADHESION OF CONTACT. 625 of the atmospheric-pressure principle is the Adhesion of Contact, which is fully developed only when the contact of the plate is com- plete. A vacuum cavity, acting as such, gradually draws the gum into it, and finally fills it by a more or less permanent enlargement; when thus filled, the plate is retained solely by the adhesion of contact. When a cavity, intended to hold up a plate, leaves no prominence or mark in the mouth, it unmistakably proves that it is exerting no force ; so far from aiding in the retention of the plate, it diminishes the force of adhesion by the presence of air, and has no compensating advan- tage, except in removing pressure from a hard palate membrane. There are, hoAvever, other and better ways of obtaining an air-space, as elseAvhere explained, without the presence of a cavity, Avhich marks the failure of its original purpose. ADHESION OF CONTACT. Full plates, which are designed to adhere by force of contact, differ from those retained by spiral springs, in that the former are larger than the latter, covering more of the palate, so as to give a larger surface for the pressure of the atmosphere. They may cover the Avhole of the outer surface of the alveolar ridge, and a considerable portion of the roof of the mouth; but should not go as far back, nor run so high up, as some dentists are in the habit of extending them. If allowed to cover those parts of the bone, where the cheek-muscles on the outside of the ridge, or the palate-muscles at the back of the mouth, are inserted, the gums will be chafed or ulcerated, the patient nauseated, and the piece rendered unstable by the action of the muscle. It is not always necessary to employ a very wide plate to give secure reten- tion, for a comparatively narroAV one will often adhere Avith very great te- nacity to the gums. But such a plate is more liable to be bent, and lose its perfect adaptation to the parts, than a Avide one, unless made thicker in proportion as it is narroAver. As it is never necessary to make an upper plate so narrow as a loAver one, there can be no difficulty in giving the requisite strength, either by increas- ing the thickness throughout, or by doubling the anterior half. The diagram (Fig. 287) represents half-section outlines of six modifications of form in the posterior mar- gin of the plate, where it is proposed to overcome the difficulties incb 40 626 ADHESION OF CONTACT. dent to a hard palatine membrane by cutting out the plate. The line P, curving forward from a little behind the termination of the top of the ridge (dotted line), is the extreme limit of any plate not compli- cated with cleft-palate. The curve a or ay will give surface sufficient for the retention of most plates, except in small arches. This form is more agreeable to the patient than the first, and is less apt to produce nausea; it removes the plate from all action of the palate-muscles, and lessens the liability to dislodgment, often caused by the forcible action of the tongue against the back of the palate, in certain efforts of deglu- tition. The curve b or by may often be used solely to avoid unneces- sary covering of the palate. In mouths of average size, and having moderate and regular softness, such shape "will prove quite as firm as one following the line P. But these lines are more frequently to be fol- lowed, for the same reason that we take the curve c or c\ to keep the plate off the hard central ridge. When this ridge is narrow, we give greatest width to the plate by following the curves on the side R of the diagram; but if the surface is broad, the space must be widened, asxm the side L; and the plate made thicker. This method of relieving the central bearing of plates gives them great steadiness on the ridge, and has an advantage over other methods, in having no band or ridge of plate pressing along the line P — a point very often as hard as any other part of the palate. It is advisable, in those cases where a vacuum cavity has been tried with unsatisfactory results, to cut out the cavity and part behind it, and thus try the effect of a plate folloAving curve b or c. There are other methods of taking off the central bearing of plates. When the ridge is soft, a wax impression does this by compressing the gum. Models from plaster impressions are scraped on the ridge for the same purpose; but this is not so good a plan, as it is difficult to do it uniformly. A much better expedient is to brush some thin plaster over the central part of the model, being careful to mark the line of the back edge of the plate, and put no plaster there: this layer must not be thicker than a card, and should have no abrupt edges. In deep arches, the shrinkage of the zinc-die accomplishes the same object; if the model is carefully scraped along the back edge of the plate, this part will fit closely, while the central portions will stand off; this is far better than the attempt to adjust the edge with pliers. In adapting atmospheric-pressure plates, the form and fit of the alveolar margin must be considered. Close adaptation of this edge is by no means so essential to firm retention of a full upper piece as in the posterior margin; for the reason that, in most cases, the loose mucous folds, which lie against, the plate, prevent the access of air. But closeness of fit is very desirable for other reasons: to prevent ADHESION OF CONTACT. 627 lateral motion; to avoid unnecessary fulness; to prevent irritation of the soft parts by projecting edges of metal. The form of the alve- olar edge is not essential to adhesion, provided it rises high enough to give steadiness to the plate. ^Esthetic considerations, hoAvever, often compel us to run the plates up as high as the muscular attachments will permit; either for the support of an artificial gum or to restore sunken features. In both juavs, especially the lower, the effort to get the deepest possible edge often gives instability, by subjecting the piece to the action of the facial and lingual muscles. In any case of doubt make the plate too shalloAV rather than too deep; especially when the edge is turned over, which makes it impossible to take off any excess Avithout spoiling the plate. Full lower plates are held by adhesion of contact; but in these the weight of the piece increases the adhesion. The surface is so small that every part of such plates should fit the gum with accuracy. The simple rule for the form of loAver plates is to extend them as far on the inner and outer edges as the muscular attachments Avill permit. The outer and inner edges are often rounded by soldering a gold wire, after determining the exact outline. Thickness of edge is also given by doubling the plate necessary for the strength of narroAV plates. The second plate is to be swaged precisely as the first; then, after partial trimming, the two plates are swaged together over a new die. One should be wider than the other, on the outer or inner edge, to give a place for the solder; the borax-cream should be free from granules, and the bloAv-pipe flame directed on the edge opposite the solder. A simple and convenient clamp for binding plates together, or holding rims whilst being soldered, is made of iron (or nickel) Avire (Fig. 288). a The first bend; b the second bend ; c a side view of the same; d side view of clamp, open and grasping tAvo pieces of plate. The curves should be so adjusted that the points of contact Avith the plates Avill be just opposite, else clamp or plates are liable to change position. Partial pieces may also be retained by closeness of adaptation ; but there are tAvo elements of instability Avhich usually will prevent them from having the security of full sets, or of partial clasp-pieces — lateral movement and extent of margin, admitting air on slightest motion. All such pieces should, if possible, have two stays, one on each side of the mouth, to prevent lateral motion ; they should cover an extent of surface proportioned to the number of teeth ; the edges of the plate should fit with great 628 THE VACUUM CAVITY. accuracy. If the exact outline of the plate is determined on, a good plan is, to paint the model with a coat of thin plaster, keeping one- eighth inch inside the margin, and laying an extra coating over very hard places ; this causes the edge to sink slightly into the gum ; yet, if carefully done, it will not change the general contour of the sur- face. Partial plates, holding the eight, ten, or twelve anterior teeth, if assisted by stays against the remaining molars, are nearly or quite as firm as full plates. But, in either partial or full pieces, whenever the plate has to be cut off, for setting the six front teeth directly on the gum, this dentated margin is more apt to admit air than the upturned rim, which has the folds of the lip lying against it. Partial lower plates are unstable, not from any admission of air, but because of the small extent of surface, inadequate to the pressure of mastication. THE VACUUM CAVITY. In some mouths the base-plate of a full upper piece adheres, from the beginning, with great firmness. When the gum is moderately and regularly soft, the palatine arch deep, and the mouth of average size, want of adherence, on trial of the plate, is positive evidence of defect in construction. But very hard, or very small, or very shallow mouths usually require time for the perfect adaptation of the best made plates. Dr. Dwindle thus explains the temporary failure of a simple atmos- pheric-pressure plate to fit firmly when first inserted. When the plate is applied and an effort made to exhaust the air, the gums are drawn down so as to meet it, along the line and behind the edge of the plate, thus resisting every effort, made from without, to withdraAV the air from the central part of the plate; so that the pressure of the atmosphere is exerted upon only a small breadth of surface, along its edge, Avhere the adhesion is constantly liable to be disturbed in mastication. With the view of obviating this difficulty, the idea of constructing a plate Avith a cavity suggested itself to the author as early as 1835, and was mentioned at the time to several of his professional brethren. The construction of the chamber then devised was found objectionable, and he abandoned its use; and it was not until the early part of 1848, when he had the opportunity of seeing a cavity-plate upon a plan contrived by Dr. J. A. Cleaveland, two or three years previously, that he Avas again induced to construct a base-plate of this kind. Dr. Dwindle made a cavity-plate, with an external opening and valve for exhausting the air, in the winter of 1845; and in the summer of 1847 or 1848, Dr. Jahial Parmly exhibited to the author a plate, Avith a simple cavity struck into it by swaging. Some months after, he heard for the first time of a cavity-plate patented by Mr. Gilbert, of New THE VACUUM CAVITY. 629 Haven. The cavity now generally employed is formed on the median line, either far back for full plates (Fig. 289), or immediately behind the alveolar ridge for some partial plates. Dr. Flagg adds two lateral cavities on the slope of the palate, with a view to prevent the plate from rocking, and to give it increased stability. Dr. Levett's lateral cavities are placed directly upon the ridge. (Fig. 290.) With this brief Fig. 289. Fig. 290. history of cavity-plates, Ave shall proceed to give a concise description of the manner of constructing them. The folloAving is the mode of construction of Dr. Cleaveland's cavity-plate, which, for reasons given below, is now seldom used. A metallic die and counter-die having been obtained, a plate is swaged, covering the entire alveolar border and extending back as far as the line P (Fig. 287). This done, it is placed in the mouth, and if found to be accurately adapted to the parts, it is removed; a half- round gold Avire, about the size of a common knitting-needle, is then soldered to the lingual side of the plate, enclosing a space shaped someAvhat as is shoAvn in Fig. 289, varying in size and form with the differences in shape and size of the plate and alveolar ridge. The part Avithin the wire is next cut out Avith punch-forceps, or saAv, and the plate placed on the model; a piece of Avax, about a tenth or twelfth part of an inch in thickness, having a circumference one-fourth greater than the hole in the plate, is then placed over the opening, extending a short distance beyond the wire on every side. The Avax at the outside is brought to a thin edge, and is also made thinner in the centre than where it covers the Avire surrounding the opening in the plate. From this model with plate and Avax upon it, die and counter-die are obtained Avith Avhich to swage a thin plate of gold, large enough to cover the Avax; its edge is chamfered off, and it is then soldered to its place on the plate, where it may be secured, during soldering, either by iron Avire clamps or by gold rivets. A sectional view of the cavity is represented in Fig. 291, A. The Cleaveland cavity causes the plate to adhere Avith great tenacity; as, from its shape, it is impossible for the mucous membrane entirely to 630 THE VACUUM CAVITY. fill it; the traction of this cavity is constant. A serious objection to its use is the great irritation it excites in the mucous membrane, in the majority of cases. The simpler cavity-plate used by Dr. Jahial Parmly, of New York, and patented by Mr. Gilbert, of NeAV Haven, may be formed with nearly as much ease as a plain plate. Fig. 291, B, represents a sec- tional view of this description of plate. ' If it is desired to have lateral Fig. 291. cavities, three pieces of wax are placed on the plaster model —one A in the centre, as already described, and one on the slope of the alveo- 3 lar ridge, on each side. When it is desirable to make a cavity Avith . ^r ^V Jq sharply defined border D, a second ^"^ plate, a little larger than the pro- D jection, should be SAvaged over the base-plate. From the base-plate the projection is to be cut out, and the smaller plate soldered over the opening. For hard mouths, the thickness of the main plate will give sufficient depth of cavity C; in this case no projection is to be placed on the model. Should the usual method of exhausting air from these cavities be thought insufficient, the valve of Dr. Dwindle (Fig. 291, V) may be inserted in the plate covering the cavity. The conical portion is neatly fitted by grinding: the stem is soldered to a spring on the pala- tine surface. A valve of easier construction is given at V; a small rubber pad acts, by the spring, upon the outside of the hole. The size of valves and thickness of plate are exaggerated, the better to illustrate the details of construction. By means of either of these valves, a vacuum may be created, which will draw Avith great force upon the membrane over the cavity. The forms B and D, Fig. 291, necessitate a prominence in the die, which is variously formed. When the die is made by sand-moulding, a corresponding one formed of wax, lead, tin, or plaster, is put on the model; a die made by dipping, or pouring, or by the fusible metal process requires plaster. Dies made by pouring into the impression require the cavity to be cut out in the impression itself. A variety of shapes in tin and lead are furnished by the depots, chiefly for vul- canite Avork; but they may be used also for the sand-moulding model. Plates made by the metallo-plastic processes require plaster prominences. The size, depth, form, and position of the cavity are important con- siderations. In size, it must be proportioned to the plate. Fig. 292 THE VACUUM CAVITY. 631 gives a fair average size, and is excellent in form, except that it is unnecessarily pointed; all angles and sharp corners should be avoided, and fanciful shapes are aesthetic blunders: the form should appear to groAV out of some neces- sity ; and hence it should be modi- fied to suit the form of plate. Shallow cavities may be larger than deep ones; partial pieces usually have a cavity larger in proportion. In depth, the cavity must vary with the softness of the membrane. If soft, it quickly fills a shallow cavity, and is less liable to injury by a deep one. Sharp-edged cavities fill less quickly than round-edged ones. They may vary in thick- ness from No. 14 to No. 24, gauge plate, page 535. When the cavity is designed, after a temporary retaining power, to act permanently in relieving pressure on central hard parts, it should be very shallow. When, in Very flat mouths, it is proposed to prevent lateral motion by the mucous prominence, the cavity should be deeper. Extreme depth, with a view to keep up constant action, makes a most unsightly piece, and injures the mouth. As to position, there Avould seem to be much difference of opinion, if Ave judge by the various points selected. We have never had but one opinion on this subject, and that is in favor of the central cavity. The cavity resists the greatest force of displacement, Avhen applied at right angles; as this force is ahvays nearly or quite vertical, it follows that the most effective cavities are horizontal; hence, they should only be on the roof of the palate, and limited to its level portion. Cavities covering the rugse, or sloping Avails of the palate, act at disadvantage. Again, after the cavity ceases to act, its secondary use in relieving pressure can be available only in this position. The very Avorst posi- tion for a cavity is on the ridge of either upper or lower jaAV. Firm pressure on the ridge is one of the most important elements of stability in a plate. It is difficult to comprehend what compensation for the loss of this is found in the cavity. Partial plates require, when the cavity is used, a modification of form to- enable the cavity to be placed on the roof of the palate. Yet the shapes elsewhere given may be used in connection with Flagg's lateral cavities as represented by the oval in Fig. 293. If no 632 THE VACUUM CAVITY. stays can be used, as in a piece of artificial bicuspids and molars with natural incisors and canines, a central or two lateral sharp- edged cavities may be of service to prevent lateral motion. In all other partial cases stays may be used; these combined Avith accurate fitting will give as firm a piece as any form of cavity. In comparing the two applications of atmospheric pressure, it is unnecessary to add to Avhat has already been said. Dentistry, like medicine, has its fashions. The salivating and blood-letting fashion of a bygone age is matter of sad Avonder to the physician of the present day ; because adopted not alone by the routine practitioner, but by men of profoundest learning and Avidest experience. The universally preva- lent fashion of the vacuum cavity, Avhich characterizes the decade in dental mechanism just passed, will form the subject of Avondering comment to some future generation. As, in times past, no case of pleurisy Avas permitted to take its chance of recovery without the preliminary bleeding; so, in these days, many of our best mecha- nicians can scarcely be persuaded to alloAV any plate to display its power of attachment, Avithout the inevitable cavity. Thousands of plates, that are Avorn without leaving their mark on the palate, give evidence of its uselessness; ulcerated mouths speak in strong language of its injuriousness; Avhilst the myriads of slovenly-made pieces that are thus temporarily stuck to the mouth, until in the fervor of satis- faction the bill is paid, attest the injury Avhich this perverted ap- plication of a valuable principle has Avrought upon the moral and artistic status of the profession. In \riew of this last influence, whilst acknowledging its occasional utility, Ave urge its total exclusion from practice: we unhesitatingly assert that any skilful mechanician Avho shall do so will never have occasion to feel that he has lost any real advantage. The processes heretofore described, and the rules laid down, have been considered mainly in their relation to artificial teeth mounted upon gold plate by the operation of soldering. But other metals may be swaged by the same processes, as platinum, aluminum, and silver. Silver is the least valuable of these, and has nothing to recommend it except its cheapness, in which questionable merit it has aluminum and vulcanite as its competitors; and hence it is noAV not very much used. It is manipulated in all respects like gold ; except in the oper- ations of refining by acids, the composition of solders used, and the care necessary in soldering, from the fusibility of the plate. As every good dental mechanic values his work far beyond the mere cost of CONTINUOUS ARTIFICIAL GUM. 633 material, Ave can in no case recommend silver as a base-plate. Patients, who can pay the greater cost of the work, can pay the lesser cost of the gold; and dentists, who can afford to give the Avork, can give the gold still more easily. We assume that he who gives work gives his best; otherwise he gives away his reputation also — an excess of generosity not to be commended. Aluminum can be rolled into plate, and SAvaged. It requires extreme care in annealing, but makes a rigid, strong, and very light plate. It does not Avithstand the buccal secretions as well as tAventy-carat gold, but is nearly or quite as good as eighteen-carat gold. The obstacle to its general use lies in the fact that, as yet, there is no good solder for it. Hence it is necessary to attach the teeth by vulcanite. This can be very successfully done, as vulcanized rubber adheres more closely to this metal than to any other, excepting, perhaps, pure gold or pure platinum. The process will be described in the section on vulcanite: it is equally applicable to twenty-carat gold and to platinum, but not at all to silver. Platinum, if alloyed with five to ten per cent, of gold, has stiffness sufficient to be used as a base-plate, in the manner previously given for gold. As it has no advantage over gold Avhen used in this Avay, its less cost is not a sufficient offset to the inconveniences attending its use and to the color, Avhich is so objectionable to most persons that they are unwilling to pay as much as for the same Avork in gold. Platinum has, hoAvever, one remarkable property, possessed by no other used by dentists except palladium, which is now scarcely at all, if ever, used. It cannot be fused in the highest heat of the forge or porcelain-baking furnace. Hence it is the only metal used for the metallic pins and other fastenings inserted into porcelain teeth ; requiring for its fusion the flame of the oxyhydrogen bloAv-pipe. It is also the only metal used in a remarkably beautiful style of Avork knoAvn as the Continuous Gum Work, which forms the subject of the next section. TEETH SET UPON PLATINA WITH A CONTINUOUS ARTIFICIAL GUM. The idea of uniting porcelain teeth to a metallic base by means of a fusible silicious composition originated in France, where the method has, to some extent, been practised since 1820. But Dr. Fitch, who spent much time in Paris, and Avas well acquainted Avith the French method and Delabarre's formulas, states, that the latter had never per- fected his recipes, or brought them into practical use. The composition employed there, judging from the specimens Avhich the author has in his possession, cannot be used in connection Avith porcelain teeth con- taining as large a proportion of felspar as those manufactured in this 634 CONTINUOUS ARTIFICIAL GUM. country. Ddabarre's compound, according to Dr. Locke, required 3761° Fahrenheit to fuse it completely. Below this, it fused imper- fectly, and was found too fragile. The process now known as the Continuous-Gum consists essentially of a silicious paste, similar (except more fusible) in composition to that of Avhich the teeth are made, which is applied around the bases and fastenings of teeth previously soldered upon a plate of purest platina, and then fused at a temperature of about 2200° Fahrenheit. It takes its name from the fact that, unlike blocks or single gum teeth, it presents an unbroken continuous gum outside the alveolar ridge, as is shown in Fig. 294. It is applied in two layers — a yellowish white body, giving the general contour of the gum, and an enamel to produce that correct imitation of the nat- ural gum, for wdiich nothing but ceramic materials have as yet been found suitable. Dr. Allen covers with the same material the entire lingual surface of,the plate, and also certain projections outside of the molars and above the cuspids, designed by him for the restoration of the natural fulness of the face. This falling in of the features is due to the absorption of the alveolar ridge, and cannot be fully restored by an artificial set of teeth, as usu- ally made; since, if the molars were set out to the original width of the teeth, the force of mastication would fall outside the absorbed alveolus and render it practically useless. Dr. Allen's device corrects this sinking, under the malar prominence of the superior maxilla and in the canine fossa, and thus greatly aids in the restoration of the face to its original appearance. This process was patented by Dr. John Allen, in 1851; but the priority of invention was contested by Dr. William H. Hunter, in a suit, the progress and result of which are well known to all readers of the journals. Dr. Allen surrendered his patents of 1851, owing to certain defects in the same, and in 1856, a new patent was issued to him for the process as then improved. The process is very generally known as "Allen's Continuous Gum," the materials for which, as pre- pared by him, can be obtained at all the depots. The formulas given in this chapter are those of Dr. Hunter, and the earlier ones of Dr. Allen. As all such materials are more perfectly prepared on a large scale, we think it much better to purchase than to make them. A "continuous-gum" piece, made in the most perfect manner, is only surpassed in point of beauty by the occasional productions of a very few block carvers ; but so rare are these specimens of perfection CONTINUOUS ARTIFICIAL GUM. 635 in block Avork, that we may safely say of the continuous-gum work that, Avhen properly made, it is the most beautiful, as it certainly is the purest and sweetest, that can be worn in the mouth, so long as the porcelain covering maintains its integrity. As regards this important point, durability, our own experience does not permit us to speak con- fidently. It was thought, when this method of mounting artificial teeth Avas first adopted, that the springing of the plate in the act of mastication Avould cause the gum to crack and scale off; Avhich did occur in a large proportion of the cases. Although the injury could be repaired by replacing the loss with fresh composition, and fusing it to the fractured edges of the remaining portions and to the plate, yet this formed a very serious objection to its use. But later improve- ments in the strength of the compound, and also in the rigidity of the plate and soldered backings, have so far corrected this evil, that it is perhaps no more liable to accident while in the mouth than any other kind of work. But, out of the mouth, its Aveight renders it peculiarly exposed to accident; a fall is almost certain to break one or more teeth, or crack the silicious covering of the plate. Hence, it is neces- sary to impress upon the patient the great importance of the most careful handling. By uniting the teeth to each other near their base, and to the plate with a glazed porcelanic material, the cleanliness of the substitute is most perfectly secured ; as all the openings beneath and around them are completely closed, excluding the secretions of the mouth and par- ticles of food, Avhich have no affinity for or action upon the porcelain. In this respect, they are superior to the most perfectly mounted block teeth; Avhile the labor of putting up a set of the former can be per- formed in half the time required for making and mounting a set of the latter. A person Avho can mount single teeth well may acquire a knoAvledge of this method, with proper instruction, in a feAV Aveeks : although much of the peculiar talent required in block-carving is needed in arranging the teeth and shaping the gum for this process, the details are comparatively simple, and may soon be taught. Of course, much practice will be required, especially in the management of the furnace heats. The necessity for such practice, to enable one successfully to manage the furnace, is the chief obstacle to its casual use by the practitioner. Unless he makes it a specialty, and does all his own work, and some for his neighbors, he will be certain to meet with many discouraging failures in the final process of baking an otherwise perfectly constructed piece. We therefore advise the dentist to swage the platina plate, select and arrange and articulate the teeth ; for no one should be so competent, to this as the one whose intercourse Avith the patient enables him to judge 636 CONTINUOUS ARTIFICIAL GUM. exactly what form, color, and arrangement of teeth are best suited to the case; and only he can decide upon the correctness of the fit of the plate. But when all this is done, the piece should be securely packed, and sent by express or mail to Dr. John Allen, of NeAV York, or some experienced Avorker in the Continuous-gum. The piece will be returned with the plate unchanged in shape, and the porcelain Avork executed in such style as can be reached only by constant practice and familiarity with the special details of this work. The artificial gum consists, as Ave have stated, of tAvo parts; the first is termed the base or body, as this constitutes the principal part of the cement, and is used for filling in between the teeth and building up the gum on the plate ; the other is gum-enamel. The materials employed by Dr. Hunter, in the composition of his compounds, are silex, fused spar, calcined borax, caustic potash, and asbestos. The silex and spar should be of the clearest and best quality, and ground very fine. The asbestos should be freed from talc and other foreign substances, and reduced to a fine powder. He gives the following formulas and directions. Flux.—Take of silex, 8 oz.; calcined borax, 4 oz.; caustic potash, 1 oz. The potash is first ground fine in a wedgeAvood mortar, and the other materials gradually added until they are thoroughly mixed. Line a Hessian crucible (as white as can be had) with pure kaolin, fill with the mass, and lute on a cover of a piece of fire-clay slab with the same. Expose to a clear, strong fire in a furnace with coke fuel, for about half an hour, or until it is fused into a transparent glass, Avhich should be clear and free from stain of any kind. This is broken and ground until it will pass a bolting-sieve. Granulated Body. — Spar, 3 oz.; silex, H oz.; kaolin, h oz.; completely fused. Break and grind so that it will pass through a wire sieve No. 50, and again sift off the fine particles, which pass through No. 10 bolting cloth, Avhich leaves it in grains about the size of the finest gunpoAvder. It may be made of hard porcelain, fine china, or wedgewood ware. Body.—Take flux, 1 oz. ; asbestos, 2 oz.; grinding together very finely, completely intermixing. Add granulated body, Vi oz.; and mix with a spatula to prevent grinding the granules of body any finer. Enamels. — No. 1. Flux, 1 oz.; fused spar, 1 oz.; English rose- red, 40 grains. Grind English rose-red extremely fine in a mortar, and gradually add the flux, and then the fused spar, grinding until the ingredients are thoroughly incorporated. Cut doAvn a large Hess- ian crucible, so that it will slide into the muffle of a furnace, line with a mixture of equal parts silex and kaolin, put in the material, and raise CONTINUOUS artificial gum. 637 the heat to the point of vitrification, not fusion, then withdraAV from the muffle. The result will be a red cake of enamel which Avill easily leave the crucible, Avhich, after removing any adhering kaolin, is to be broken down and ground tolerably fine. It may now be tested, and, if of too strong a color, tempered by the addition of covering. This is the gum which floAvs at the lowest heat, and is never used before sol- dering. No. 2. Flux, 1 oz.; fused spar, 2 oz.; English rose-red, 60 grains. Treat the same as No. 1. This is a gum intermediate, and is used upon platina plates. No. 3. Flux, 1 oz.; fused spar, 3 oz.; English rose-red, 80 grains. Treat as the above. This gum is used in making pieces intended to be soldered on, either in full arches or in the sections known as block work. It is not necessary to grind very fine,, in preparing the above formulas. Covering. — What is termed covering is made by the same formulas as for the enamel, omitting the English rose-red. Being with- out any coloring Avhatever, it is used for tempering the aboAre enamels Avhen too highly colored, Avhich may be done by adding, according to circumstances, from one to six parts of covering to tAvo of enamel, thus procuring the desired shade. When it is to be used for covering the base prior to applying the enamel, it may be covered with titanium, using from tAvo to five grains to the ounce. Investient. — Take tAvo measures of Avhite quartz sand, mix with one measure of plaster of Paris, using just enough Avater to make the mass plastic, and apply quickly. The slab, on which the piece is set, should be saturated with water to keep the material from setting too soon, and that it may unite with it. Memoranda. — In preparing material, always grind dry, and use the most scrupulous cleanliness in all the manipulations. In all cases where heat is applied, it should be raised gradually from the bottom of the muffle, and never run into a heat. Where it is desired to lengthen any of the teeth, or to mend a broken tooth, it may be done with covering, properly colored Avith platina, cobalt, or titanium. In repairing a piece of Avork, wash it Avith great care, using a stiff brush and pulverized pumice-stone. Bake over a sIoav fire to expel all moisture, and Avash again, Avhen it will be ready for any new applica- tion of the enamel. Absorption, occurring after a case has been some time worn, by alloAving the jaAvs to close nearer, causes the lower jaw to come fonvard and drive the upper set out of the mouth. By putting the covering on the grinding surfaces of the back teeth in sufficient quantity to make up the desired length, this difficulty may be to some extent remedied. 638 CONTINUOUS ARTIFICIAL GUM. Any alloy, containing copper or silver, should not be used for solder or plate, if it is intended to fuse a gum over the lingual side of the teeth, as it will surely stain the gum. Simple platina backs alone do not possess the requisite stiffness, and should always be covered — on platina with the enamel, and on gold with another gold back. In backing the teeth, lap the backs, or neatly join them up as far as the lower pin, in the tooth, and higher if admissible, and in soldering be sure to have the joint so made perfectly soldered. The compositions, originally employed by Dr. Allen, consist of— Body: Silex, 2 oz.; flint glass, 1 oz.; borax, 1 oz.; wedge-wood ware, 1? oz.; asbestos, 2 drachms; felspar, 2 drachms; kaolin, 1 drachm. Enamel : Felspar, £ oz.; Avhite glass, 1 oz.; and oxide of gold, 1$ grs. Since the publication of the seventh edition of this work, great im- provements have been made by Dr. Allen in the composition and prep- aration both of the body and gum-enamel, Avhich are furnished by the manufacturers, and may be obtained at any of the dentists' fur- nishing establishments at a very moderate price. The metals Avhich may be employed for the base in this method of mounting artificial teeth are platina or pure palladium. The common commercial article of palladium is not pure, and is never used in this country. Platina, alloyed with from one to ten per cent, of pure gold, may also be used; but it is objectionable from its liability to spring or warp. It makes a stiffer plate, and so far has the advantage over pure platina, but for the reason given the purest metal should be selected. Because of its softness, it must be used thicker than gold plate. The process of swaging the plate is the same as before given. It must be often annealed, and gradually carried into any deep depressions, for its softness makes it more liable than gold to be torn, made thin, or punched through. A narroAV rim, partially turned up, is to be left around the outside. The process of articulating, etc., is similar to that for gold. In adjusting the teeth, accurate grinding is unnecessary; but each tooth should touch the plate. Part of each backing should lap over the adjoining ones, and, behind the six front teeth, should also be lapped over an additional narroAV band, to give greater rigidity to the plate. In this process, there is great opportunity to give to the teeth that irregularity of arrangement Avhich forms one of the charac- teristics of natural teeth ; neglect of which gives to many, otherwise excellent pieces of work, an unnatural, artificial appearance, that shoAVS great deficiency in the cultivation of dental aesthetics. Before backing the teeth, the piece may be tried in the mouth, and any inaccuracy of articulation readily corrected ; careful articulation makes this trial unnecessary; but if from any causes changes are found on trial to be needed, they can be made more readily in this CONTINUOUS ARTIFICIAL GUM. 639 work before the gum is added, than in any other; since no joints or neat fitting to the plate are disturbed by changes in the position of a tooth. After they are backed, the piece should be set in a mixture of plaster and asbestos (Dr. Allen prefers asbestos to sand), resting on a muffle-slide, and coming up around the outside of the teeth, to keep them in place. The solder used must contain no trace of either silver or copper, as they will stain the gum-enamel and body; but must be either pure gold, or alloyed with about five per cent, platina. Borax may be used, not in this case as a flux — for Avhere there is no oxidation no flux is required — but to tack the pieces of solder to place until ready to Aoav. The slide is then gradually carried into the muffle, and the whole piece raised to the melting-point of the solder. The form of furnace, and rules for the management of the heat, are the same as hereafter given for block work. The heat required for this is not, however, so great as that required in block work; the gold and the continuous-gum materials fusing at about 2200° Fahrenheit. Having thus soldered and cooled off the piece very gradually, it must be thoroughly Avashed, so as to remove every particle of invest- ment. Then, wdth a camel's-hair brush and small knife, such as are used in block-carving, the spaces between the teeth and plate are to be perfectly filled with a finely-compacted paste of body and rain-Avater. The paste must be applied very moist, so as to exclude the air and run into all the spaces; then dried with cloth or blotting paper, and compressed with the knife. If the lingual surface of the plate is to be covered, this should be made rough by soldering small clippings of platina over it, at the time the teeth are soldered. The natural rugas of the palate should be imitated in the thin layer of body which is applied. The work must then be slowly and thoroughly dried, and the piece put on a slide Avith the coronal ends of the teeth dowmvard, and im- bedded to the depth of an eighth of an inch in a thick batter of plaster and asbestos. But if the teeth are very securely soldered, it will be best to flow the body with the plate resting, teeth upAvard, on the plaster and asbestos model on Avhich the soldering was done. The slide is then gradually introduced into the muffle, and subjected to a heat sufficiently high to fuse the compound —say, twenty-two hun- dred and fifty degrees. It is then AvithdraAvn sloAvly, and completely cooled. Usually there will be cracks and flaAVS Avhich need filling with paste. The outside rim is also to be turned doAvn over the edge of the body with hammer and pliers, and any defects at this point filled up ; then heat a second time with the same care as at first. The piece, noAV ready for enamelling, should present a semi-vitrified appearance; if too highly glazed, it is too much done, and the enamel 640 PLASTIC WORK. will not take so firm a hold; if too dull-looking, it is not sufficiently baked, and will be deficient in strength. The enamel must be applied moist, and is best put on Avith a brush : much plastering Avith the knife makes it apt to fly off in baking, and for the same reason it must be heated very gradually. The layer of enamel should be thin and irreg- ular, the yellowish Avhite of the body shoAving more or less through it, so as to give the variations of tint observed in the natural gum. If a thick and even layer is applied, the result will be an unnatural uniform color, Avhich will destroy much of the peculiar beauty of this work. The greatest care is necessary, in applying the paste, to remove every particle from the parts of the teeth and plate Avhich are not to be covered, as it adheres with great tenacity and roughness, and dis- figures these parts. Much experience is also necessary in determining the exact heat necessary to develop the full beauty and strength of the Avork. Repeated heatings, either for the first making or for re- pairs, do not injure the plate or teeth, provided proper care is taken to heat and cool gradually; and provided, in case of repair, the piece is thoroughly cleaned in strong soda, to remove all trace of the buccal secretions. This Avork is peculiarly adapted to full loAver dentures. The prin- ciples of construction are precisely the same, only the plate should be very heavy, and the extra band behind the six or eight front teeth very thick and strong. Many use it for partial cases ; for which, how- ever, the author does not regard it as well suited. The three distin- guishing advantages of the continuous-gum work are its ready adapta- bility to every variety in shape of gum and arrangement of teeth, its extreme beauty, and its great cleanliness; its three disadvantages are its Aveight, its liability to be broken by accident, and inapplicability to partial cases. CHAPTER XIV. MOULDED PLATES OF PLASTIC MATERIALS. IN the classification of operations, for the Replacement of Teeth, given on pages 485-7, difference in the order of these operations was made the ground-work of a division of all base-plates into two classes: Swaged and Plastic. In describing, up to the point of completion of the model, the operations common to both classes, the PLASTIC work. 641 modifying requirements of each were duly considered. The special order and details of swaged wTork were then taken up, Avith incidental allusions to plastic work, by way of comparison or contrast. Operations, materials, and apparatus peculiar to the latter, will form the subjects of this and succeeding chapters. Plastic work includes all dental substitutes, in Avhich the base- plate is brought into contact Avith the teeth and the model of parts to be fitted, whilst in a fluid softened or plastic condition, then hard- ened, during continuance of this contact, either by the application or the withdraAval of heat. Plasticity, as thus used, is the property of being moulded, and has already been spoken of as an essential quality of impression materials. In them it is associated with other qualities especially fitting them for their particular use ; so in plastic work, mere plasticity is of no avail, if other properties do not give to the material the qualities essential to a base-plate. It must have strength and durability, and must be in harmony with the parts to Avhich it is applied. This harmony implies that it shall not act injuriously upon the mouth, or receive injury from it; that it shall not, in form, color, taste, or smell, be repulsive to patients. It ought not, if possible, to be even objectionable; but tastes are so variable, that this contingency cannot be a positive ground for exclusion of an othenvise valuable material. As, in swaged work, there are four metals of which plates may be formed — gold, platinum, aluminum, and silver — so, in plastic work, there are four varieties of plastic material of Avhich plates may be moulded: 1, Porcelain clay; 2, tin and its alloys; 3, sulphurated gum; 4, aluminum. The first tAvo have been longest in use; the third has become the most important in modern dentistry; the fourth and latest has yet to pass the ordeal of experience. The first is moulded by tools, not in flasks, as are the other three; it also requires intense heat to vitrify or harden it. The second is made plastic by fusion, requiring a flask, hot to prevent cracking of teeth, and tight to prevent escape of metal: these plates harden by cold. The third, less plastic, demands force in the act of moulding: it is hardened by heat; but the tempera- ture to which the teeth are subjected is less than in the other three. The fourth is made plastic by fusion ; but, though more plastic than the third, it does not Aoav as readily as the second; its extreme light- ness and sluggish flow necessitates peculiar apparatus in mouldiug. Comparing them in respect of certain other properties—weight, durability, strength, and necessary thickness of plate; amount of change in shape from contraction ; resistance to change by the action of the buccal fluids — Gum is lightest; aluminum, being thinner, is very nearly as light; porcelain, though a light substance, requires such 41 642 PORCELAIN PLATES. bulk, that it is heavier than either; tin and its alloys are heaviest. Gum plates, properly made, are strong, durable, and may be as thin as any, except aluminum ; aluminum plates are thinnest and strongest, their durability is still an open question ; tin alloys are variable, some being tough and strong, others stiff and brittle, others soft and flexi- ble ; they have about the same bulk as gum, and the best are perhaps nearly or quite as durable. Porcelain plates contract very much; aluminum much less, but still very considerably; tin alloys contract very slightly; gum has no contraction. Porcelain most perfectly resists the buccal secretions and substances taken into the mouth; gum nearly on quite as effectually; tin alloys undergo some change; aluminum is not changed by sulphur, as silver is, but will probably be found, in some mouths, to undergo slight change. To give uniformity of nomenclature, the four varieties of plastic work will be classed under three heads. 1. Ceramo-plastic, or porcelain. 2. Metallo-plastic, including tin, cheoplastic metal, other tin alloys, and aluminum. 3. Vulcano - plastic, including caoutchouc, gutta- percha, and all vegetable substances that, by combination with sulphur, iodine, etc., have the property of hardening by heat, under the process known as " vulcanizing." CERAMO-PLASTIC WORK. Porcelain plates are remarkable for cleanliness, and, in the hands of a skilful worker in the ceramic art, may have great artistic beauty. There are, however, several considerations that must prevent their ex- tensive use. Like continuous-gum work, ceramic plates are adapted only to full sets. They are frail, occasionally breaking under the force of powerful mastication; they will inevitably break, falling on any very hard surface. It is but just, however, to state that the few, who make porcelain plates a specialty, claim that they are no more liable to accident than other pieces; that the teeth of all, especially continuous-gum, are as apt to break as this work ; and that a broken tooth, or plate, is more easily and quickly mended in porcelain-plate work than in any other. A second objection is the great shrinkage of any strong porcelain substance. Efforts to correct in the material itself, this shrinkage, makes it proportionately weak. Correction by enlargement of the model is not only troublesome, but it is uncertain: the same is true of the correction by grinding with corundum-wheels, Avhich is very tedious, and cannot be exact. When base-plates Avere made of ivory, and fitted to the mouth by carving, this imperfection of porcelain plates was not objected to, because the former fitted no better, if as well: but in contrast with the exact adaptation of other forms of plas- BASE-PLATES OF TIN AND TIN-ALLOYS. 643 tic Avork, and of swaged plates, it becomes very manifest. There are many mouths in Avhich a porcelain plate could not be retained at all; there are others which adapt themselves so readily to moderate inac- curacies, that such a plate is worn with entire satisfaction. A third objection is the necessity of constant practice, to keep up that skill in ceramic art which is essential to an artistic piece, and to insure uniformity of result by proper control of the furnace. This difficulty, however, can be met in the same Avay as in continuous-gum work. If the dentist will make the model, select and articulate the teeth, arrange them on a temporary plate with wax, to give the ful- ness of gum, and a sample tooth to show its color, then pack se- curely, and send to any block-carver or porcelain teeth manufacturer, he can have a porcelain plate made better, and with more certainty, than only an occasional practice will enable him to do for himself. If it is desired that the teeth and plate shall be carved at the same time, it will be sufficient to send correct model and articulation, Avith direc- tions as to the style, color, etc., of the teeth. We think, however, that it will be safer for the dentist to select and arrange the teeth, as he can better judge what is appropriate than one Avho does not see the patient. For details of construction, the reader is referred to other chapters. Impression and model are made like any other work; articulating processes are the same as for other forms of plastic work ; grinding teeth is very simple, as in continuous-gum work; enlargement of the "fur- nace model " and manipulation of the porcelain mixture will be de- scribed in the chapter on Porcelain. The second and fourth varieties of Plastic work will be described in the next chapter, under the head of Metallo-Plastic Work. The third variety will form the subject of the subsequent chapter, under the head of Vulcano-Plastic Work. CHAPTER XV. METALLO-PLASTIC WORK. rnilE use of a fusible metal in the construction of base-plates is by ■ no means new ; but many of the metallic compounds suggested, or now used for this purpose, are of quite recent introduction. Except aluminum, none of them fuse above the melting-point of tin, 440°. Pure Tin is the oldest form of metallo-plastic base-plate, and Avas used 644 BASE-PLATES OF TIN AND TIN-ALLOYS. exclusively for the lower jaw. It is objectionable on account of its softness; even in a heavy lower rim, it is apt to bend, and for an upper plate it is wholly unsuited. In its resistance to chemical change in the mouth, it stands next to gold and platinum; is superior to silver and probably to aluminum; superior also, in this respect, to any of its own alloys. The process of constructing a lower plate of pure tin is the same as for any of the tin-alloys. Tin may be made harder and more rigid by alloying with Silver, Copper, Antimony, Zinc, Lead, Bismuth, or Cadmium. Copper and lead make it unfit for the mouth ; antimony, zinc, and bismuth make it brittle, unless used in very moderate proportion. Silver gives it hardness, also cadmium, without imparting the objectionable properties named. Probably the best of all alloys for tin is cadmium. Closely resembling tin in its physical properties, it hardens it without making it too brittle, or imparting increased liability to the action of fluids of the mouth. The majority of tin-alloys at present recommended for base-plates contain cadmium, with some zinc, antimony, or bismuth: they ought not to contain copper or lead. In absence of their for- mulas of composition, it is impossible to say that they will prove inju- rious or harmless in the mouth, or that they will undergo no change by time. Even if we knew the formulas, it would, in some cases, be impossible to speak positively on this point. The primary strength of any of these alloys can be easily detected; with rather more trouble, its fusion-point and free flowing qualities may be learned. For all else, the safest rule is to use any or all of them " under protest," until, by personal observation, every one ascertains for himself how far they are free from change, or keep their original strength after being Avorn. It may be thought that such distrust of the assertions of others is unprofessional. Possibly it may be; but what other course is open to any careful operator, in the face of such circulars as the one just received by the Avriter, in which a certain " rubber preparation " is recommended, as enabling the dentist to com- plete a set of teeth in " one hour after taking the impression." The sad truth is too notorious for concealment, that the inventors of dental "improvements" are like the discoverers of quack medicines — they magnify excellences, conceal defects, substitute assertion for evidence, and claim a confidence in their inventions which should only be the sIoav growth of experience. Experiments in tin-alloys, unlike those in vulcanite compounds, are easily made by any well-informed dentist: he can have his favorite tin- alloy, as he has his pet solder, both the result of his OAvn experiment- ing. He can judge at once of certain properties ; for others, he must Avait the teachings of experience. If he prefers to use the labor of CHEOPLASTIC PROCESS. 645 another, and buy an alloy Avhich pleases him, but of which he really knows nothing, Avhy should not full judgment upon this also be sus- pended until a jury of his patients have rendered their verdict. CHEOPLASTIC METAL. This alloy was patented by Dr. A. A. Blandy, of London, in 1856, together with certain processes used in the construction of dental plates. The manipulations, since so familiar in the working of vulcanite, were then as unknown as vulcanite itself. The peculiar merits of plastic work were at once recognized by many of the profession ; and the Cheo- plastic process would have passed into very general use, Avith such modi- fications as experience may have dictated, had it not been for the introduction of Hard Rubber. After some years' contest, the profession decided in favor of rubber. Dr. Blandy's departure from the States in 1862, and the failure of the supply of his metal, led to a total disuse of the cheoplastic metal. The abuses of vulcanite, and the gross mismanagement of Rubber Patents, have urged many advocates of plastic Avork to revert to vari- ous tin-alloys, which are, in their principle of composition, and in the essential character of the processes employed, identical Avith Dr. Blandy's patents. The name chosen by him (signifying the making of plates, by pouring a metal, made plastic by heat) is equally applica- ble to all alloys of tin noAV used. The alloy of the cheoplastic metal was silver, Avith some bismuth, and a trace of antimony. The exact proportions are not knoAvn, but may be learned by reference to the patents. The alloy imparted no taste whatever to the mouth; and its purity, so far as its capability of resisting the action of the secretions of the buccal cavity is concerned, Avas said to be equal to eighteen-carat gold. Its color became slightly darker after being worn some Aveeks, but was immediately restored by placing it in a strong solution of caus- tic potash. Many details of Dr. Blandy's process were adopted in the construc- tion of vulcanite ; whilst some of them may be advantageously modified by the use of moulding-flasks, etc., contrived for the latter. The mode of forming a cheoplastic model, before the invention of the flask, is shown in Fig. 221, page 550, and may be used in the absence of flasks of the proper size. If the plate is to have a vacuum cavity, one of the proper size, depth, shape, and position should be cut in the impression; this, if of plaster, is varnished, then placed on a piece of foil or paper, and surrounded with soft putty, clay, or other plastic substance. The lower edge of a tin ring is then slightly imbedded in the putty, large enough to leave a space of over half an inch between the impression and the ring, for the formation of an articulating surface for the tAvo parts of 646 CHEOPLASTIC PROCESS. the matrix: at the back part, the space should be an inch and a half, so that it may also be used as part of the antagonizing model: also by the length of the "gate," to give weight to the melted metal. The model should be an inch thick, measured from its shoulder, and is made of equal parts, by weight, of plaster and finely pulverized spar. This composition is not so hard as plaster alone, but is sufficiently so for all practical purposes : if desirable, the density of surface may be increased by the use of dilute soluble glass. The directions previously given for making models are here to be observed. Several models can often be taken from the same impression. When the alveolar ridge projects, it is sometimes necessary to cut away the outer part of the impression before the separation can be effected ; when this is done, care is necessary to prevent injuring the model. Having removed the impression, the prominence which is to form the cavity in the base-plate may be altered and trimmed before proceeding further. The next thing to be done is to make an antagonizing model: as the method of obtaining it for this process is different from any heretofore given, we subjoin a brief description. Tavo or three conical holes are made in the back part of the model, for the proper adjustment of the antagonizing portion, (Fig. 295:) a coating of varnish or soap-Avater, or very thin foil, is applied to every part except that which is to be covered by the base-plate: this part is now covered with a plate of thick tin-foil, stiffened by the application of a thick sheet of Avax or gutta-percha. A rim of wax is then placed along the alveolar border and trimmed down Avith a knife until its depth is a little greater than the length required for the artificial teeth. Remove this articulating plate, place it in the mouth, and if the rim is found to be properly shaped, request the patient to bite upon it, closing the lower jaw naturally, until a distinct imprint of all the lower teeth is made in it. (See Fig. 295.) The Avax and plate are then removed from the mouth, replaced on the model, and the other half of the articulator made ; first covering the centre of the plate C and the flanges B B Avith paper pulp, so that it shall articulate only with the back A of the half- matrix and copy the impressions of the teeth in the wax. CHEOPLASTIC PROCESS. 647 This half is then removed, also the articulating plate; and the por- tion of the model representing the alveolar ridge and roof of the mouth is to be covered with a fresh plate of tin. This is accurately Fig. 296. moulded to the various depressions and prominences with the finger, and with hard rolls of chamois leather, cut nearly to a point at each end, called stumps (Fig. 296), such as are used by artists. One or two extra strips of foil should be placed over the alveolar ridge and under the foil plate, to secure sufficient thickness of metal between the teeth and gums. A plate of prepared sheet wax or gutta-percha, No. 20, (gauge plate, Fig. 208) in thickness, covering only so much of the model as is to be occupied by the metallic base, is carefully moulded to the tin-foil plate, and trimmed to the required shape (Fig. 297). The teeth are noAV selected, ground, and fitted to the foil-plate, from the outer edge of which the wax should be removed, to permit the adaptation of the teeth or blocks. The foil-plate also should be cut away from the front of the ridge, Avhen the teeth are to be set directly upon the gum. Gum teeth, either single or in blocks of two or three, are preferable to plain teeth. As they are arranged upon the model, the ap- proximate sides should be ground until they come together so perfectly 648 CHEOPLASTIC PROCESS. at every point as to render the line of union scarcely perceptible. The teeth used in this process are constructed differently from those designed for swaged plates. Teeth and blocks having holes or dove- tail grooves were used at the first introduction of the cheoplastic pro- cess. A sectional view of these single and block teeth is given in Fig. 298, the shaded line representing the metal. These teeth are no longer made, having been superseded by the more desirable forms designed for vulcanite work. Fig. 299 represents one of the many of these designs, manufactured by Dr. S. S. White. Fig. 299. Ordinary plate teeth can be used and attached by '"^gjfpllljjlll^^ bending the platina pins, if long enough, until the ends come together. As it is not a matter of import- ance Avhether the base of the teeth fit closely to the Avax-plateornot,it is rarely necessary to do much grind- ing, except when the teeth are too long, or when the part of the ridge requires careful fitting. Each tooth or block, after having been properly ground, is secured by applying melted wax to the inner surface, Avhich fills the holes or grooves, and unites with the plate beneath. The antagonizing models are, from time to time, applied to each other to insure accuracy of adjustment: if the bite of the lower teeth has been correctly taken, no alteration will be necessary in the piece upon trying it in the mouth. The amount of wax applied to the backs of the teeth, after the grooves or holes are filled, should equal the amount of metal required to unite them firmly to the base. This may be done by putting a narrow strip extending around the inside of the arch, or it Fig. POO may be applied in small pieces; in either case using the Avax-knife, (Fig. 300,) Avarmed by a small spirit-lamp, to unite the strip or pieces to the teeth and wax-plate. Another strip is applied along the upper edge and on the outside of the teeth, filling the groove above the gum, and uniting it to the teeth and plate with the wrax-knife. This strip should be long enough to pass behind the last tooth or block on each side, and unite Avith the wrax on the lingual surface. As metal is ultimately to take the place of the wax, it is important that the exact quantity required be put on, and every part made perfectly smooth. This may be done with the warm wax-knife and brushes. (Fig. 301.) The larger for pressing it down upon the model, and the smaller for smoothing it between the teeth, where the Avax-knife cannot be con- CHEOPLASTIC PROCESS, 649 veniently employed. The use of prepared gutta-percha plates will Fig. 301. Fig. 302. save time, by limiting the use of the wax-knife and brushes, give a more uniform plate. In proportion as this part of the operation is neatly and skilfully executed, Avill the labor of finish- ing, after the metal has been poured, be lessened. An upper set of single gum teeth, thus arranged on a wax or gutta- percha plate upon the model, is represented in Fig. 302. If there is any doubt as to the proper adjustment of the teeth, the piece may noAV be tried in the mouth; any necessary alteration must be made before proceeding further with the Avork. When single teeth without Fig. 303. and 7000 650 CHEOPLASTIC PROCESS. Fig. 304. gums are used, the strip of Avax in front and on each side is pressed between them, and the festooned appearance of the natural gum given to it. A set thus prepared is represented in Fig. 303, giving an ex- ternal vieAV of the festooned wax-band. The work is placed in the tin ring in Avhich (Fig. 221, page 550) it was made — the upper edge of the ring projecting about a fourth of an inch above the summits of the teeth, as shown in Fig. 304. The exposed surfaces of the model, after cutting broad grooves on the shoulder of this half of the matrix, (see white lines of Fig. 303,) to keep the tAvo parts in proper re- lation, and of the wax (but not of the teeth), are to be well oiled, or covered Avith thin foil, and the second half of the matrix made of the mixture of plaster and spar above given. It is of utmost im- portance that the plaster batter should be worked into all the joints and interstices between the teeth, and be free from air-bubbles ; for the metal searches into the most minute space, and the attempt to cut off some little button of metal between teeth often results in their fracture. When the mixture becomes hard, the ring is removed, and the part of the matrix first made is tapped lightly with a small mallet; the two may then be easily separated : but if there is any undercut, or thin ridge, the matrix must be warmed before separation, so as to soften the Avax. This done, a groove or gate, and on each side of it two vents, are to be cut in the back part of the matrix, Avhich contains the teeth and AArax-plate; through Avhich gate the melted alloy is to be poured, the air escaping through the two vents. The length of the gates and vents adds to the press- ure on the fluid metal, and insures more certainty in the flow of the plate. It is well to have the flask of such shape as Fig. 305. CHEOPLASTIC PROCESS. 651 Fig. 306. to give a gate at least two inches long. Fig. 305 represents the gate and vents, also one-half of the wax-plate removed, shoAving the ends of a set of plain teeth. All necessary trimming of the plaster is done before the Avax is removed, to prevent small pieces from falling in the matrix by the sides of the teeth. The main body of the Avax is now removed, as the absorption of any considerable portions left in the matrix has a tendency to roughen the surface, and thus to pre- vent the metal from running as smoothly as it Avould othenvise do; but no attempt should be made to remove the wax around the teeth or pins: these small remnants of wax will totally disappear in the pro- cess of heating up. After removing the wax, each half of the matrix may be held over the flame of a tallow candle, until a slight coating of lampblack forms on it. The two parts are now bound firmly to- gether Avith iron wire, and the line of union luted with a mixture of plaster and spar, leaving the gates and vents open. This is done to prevent the escape of the metal when poured, which sometimes requires additional means of security. One method is to put the matrix, after Aviring it, with the gate and vents upward, into a sheet-iron or tin rim (Fig. 306), partially filled with a batter of plaster and spar. Another method is to bury the matrix in sand, in a sheet-iron box, about four inches square; and in this sand-bath to heat it up, until some of the cheoplastic metal, placed on the sand, begins to fuse. Or the piece, set in the rim (Fig. 306), may be placed in a kitchen range or bake-oven, and exposed to a bread-baking heat, say from 300° to 400° Fahrenheit, for from three to five hours, or until every particle of moisture is driven from it; then placed in an upright position, the melted metal poured quickly into the matrix. If there is no ebullition, and the metal comes up into the vents freely, the piece will come from the matrix in a perfect condition. If it bubbles, it may be lightly tapped several times on some hard surface. When perfectly cold, the two parts of the matrix are separated, exposing one of the surfaces of the plate. When the process is properly conducted from the beginning up to 652 CHEOPLASTIC PROCESS. the point of pouring the metal, the piece will come from the matrix perfect in all its parts. But Avhen the metal fails to Aoav freely around the teeth, and to cover perfectly the alveolar border and palatine arch, it is better to replace the removed half of the matrix; then, turning the gate down, heat it up to the melting-point of the metal; place again in the sand-bath, and pour a second time. Attempts are some- times made to patch the plate where the defects are small; but it will prove far more satisfactory in the end to pour it entirely anew. The matrix should become entirely cold before any attempt is made to remove the piece; otherwise, there will be danger from the sudden exposure of warm teeth to the air. The dried felspar and plaster mixture is easily cut; dipping it in water will make it still softer, and more easily removed. If care has been used in shaping the wax-plate, if the plaster has been kept free from air-bubbles, and if the joints between gum teeth or blocks have been nicely jointed and filled, on their front edge, in the plaster moistened with soluble glass, the piece may be finished with little trouble. The gate and vents and irregular edges of the plate may be sawed off or removed with coarse files; fine-cut files become clogged with the metal. Scrapers (Fig. 307) are made for removing Fig. 307. the roughness of surface; curved and rounded for the inner surface; flat, straight-edged, and pointed for outer surfaces or dental interstices. If carelessness in making the Avax-plate renders it necessary to cut away much thickness of metal, the lathe-burrs used for vulcanite will be found useful. In reducing the thickness of plates, frequent use of calipers (Figs. 308, 309) is necessary to avoid the accident of cutting through the plate. This is especially apt to happen in the use of lathe-burrs. Fig. 309 should have the tips on one side pointed as in Fig. 308, and they should be occasionally examined, to see if both sides come together alike. It will make the use of calipers more easy, 2603 CHEOPLASTIC PROCESS. 653 if the arms are kept permanently open by an elastic band, closing by pressure of the fingers at each trial of the plate. Graduated calipers are useful also for measuring the depth of articulating rims, the length of teeth, etc., and are quite indispensable. This donjs, the sur- face is rubbed first with coarse and afterward with fine emery-cloth, then washed in soap and water with a hard brush, afterward burnished and finished by polishing with chalk on a brush-wheel; coarse Scotch- stone may be used in place of the emery-cloth. The upper surface of the plate must neither be scraped nor polished, as the accuracy of its adaptation to the gums and palatine arch would be injured: it should Fig. 308. be Avashed simply Avell with a brush, using perhaps a little whiting. Every other part ought to be finished in the neatest and most per- fect manner; the piece is put in a strong solution of caustic potash, boiled for tAvo or three minutes, then Avashed in pure water, wiped dry, and finished with chalk and the brush-wheel. Under no circumstances should the cheoplastic metal, or any other tin-alloy, be gilded. The least imperfection of the electrotype deposit, or the abrasion of any edge or prominence, or the removal of the coat- ing by trimming the plate at any point, presents to the fluids of the mouth tAvo metals having widely different galvanic relations; electric 654 CHEOPLASTIC PROCESS. action is inevitable, causing decomposition of the plate, annoyance to the patient, and often ulceration of the gum. The cheoplastic metai, and some other tin-alloys, are quite harmless in the mouth. They all slightly tarnish, but the surface oxide seems to protect from further action, except where abraded by the mastication of food. The brilliant polish of new work cannot be kept so long as on a gold plate, because it is much softer ; this, however, is of secondary importance, provided the metal is hard enough to resist wearing aAvay under the necessary operations of use and of cleansing. In mounting a set of teeth for the loAverjaAV, the gate through which the metal is poured into the matrix should have two lateral branches, one on each side, to admit the metal more freely. The wax-plate should also be thicker, to give sufficient strength and stability to the base; in other respects, the process is the same as that described for an upper set. For a partial lower set of molars and bicuspids on each side, the wax-plate should be extended behind the remaining front teeth; and two or three thicknesses should be applied here, giving stiffness suffi- cient to prevent breaking or bending under the pressure of mastication. In making ah antagonizing model for an entire set of teeth, the Avax- plate for the lower jaw is stiffened by the adjustment of a stout iron wire, bent to the curvature of the arch, and made fast to and partly bed- ded in the plate. The rim of Avax is now arranged on the ridge, and after being properly trimmed, it is taken from the model. Upper and lower plates are then adjusted in the mouth; the articulation is obtained, and the articulator (Fig. 310) made in the manner described for a full set of teeth mounted on gold plate. Fig. 311 represents a double set of teeth arranged in wax upon a plaster articulation, ready to be placed upon their respective models preparatory to the formation of the remaining halves of the matrices (Fig. 304). The Cheo- plastic process is also applicable to partial sets of teeth : a single tooth, or several teeth situated in dif- ferent parts of the arch, can be replaced, and retained so as to occasion no inconvenience or an- noyance to the patient. The only precaution necessary to be CHEOPLASTIC PROCESS. 655 observed in their construction, in addition to that of accuracy of ad- justment and neatness of execution, is to thicken the projections of the Avax-plate between the remaining natural teeth sufficiently to give strength to the metal at these points. These portions,, when very narrow, should have twice the thickness of the other parts of the plate. Clasps cannot be used, as the metal itself has no elasticity, and gold clasps could not be connected to such plates. With this exception, the forms of partial pieces for this Avork are the same as for vulcanite work, hereafter described. After having adjusted the artificial teeth, and made them fast to the wax-plate, the teeth of the model should be cut off before making the other half of the matrix, as it would be almost impossible to separate the two halves without breaking the teeth and other important parts. But if iron flasks are used, similar to those designed for vulcanite, it is not necessary to cut off the teeth. In the same manner, as here- after described for that Avork, the model may be set in the deep half of the flask until the edges of the teeth are nearly or quite level with the edge of the flask: the investing plaster supports the outside of the teeth, and prevents breakage on separating the flask. A piece from which one or more teeth have been broken can be easilv repaired. If any portion of the tooth remain it is removed, and the metal that united it to the base filed away: a new tooth is selected, and ground until it corresponds Avith the adjoining teeth; it is then put in place, and wax appjied on the outside and inside of the tooth, smoothing it with the Avarrn Avax - knife evenly with the plate. The apex of a conical-shaped roll of wax, about an inch and a half in length, is united to the wax on the back part of the tooth : the apex should be little more than an eighth, and the base half an inch in diameter, which latter should be half an inch above the edge of the teeth. A small stem of wax is united to the Avax on the outside of the tooth, with the free extremity half an inch above its edge. A tin ring, smaller than that used in making the model, is now filled about one- third full of plaster and spar mixture, and the piece put immediately in it Avith the base downward, first filling the irregularities of the plate with the plaster: a thin mixture of the same composition is then poured on top, filling the ring, and covering the edges of the teeth about a quarter of an inch. When hard, the ring is removed, and the project- ing stems of wax withdrawn : the wax on each side of the tooth, and betAveen it and the base, will be melted and absorbed during the drying process. The matrix is dried in a stove or furnace, as in the first instance, being careful not to heat it up to the point of fusion of the plate The alloy is then melted, and poured into it through the gate behind the tooth : and if it flows, filling the vent in front without bub- 656 STANNIC ALLOYS. bling, the piece will come from the matrix perfectly restored. When cold, the plaster and spar are broken from the teeth, and the metal around the new tooth finished according to the direction given for full sets. .In repairing pieces, the heating of the matrix and metal must be done very carefully. If the matrix is too hot, the plate may fuse; if too cool and the melted metal too hot, porcelain may be cracked. In using cheoplastic metal and all other tin-alloys, in con- nection with platina pins, it should be remembered that the exposure of a single rivet to the action of the buccal fluids forms a galvanic battery, which will cause an unpleasant taste, and render the piece liable to slow decomposition ; hence all pins must be carefully covered with metal, so as not to be exposed in the finishing processes. STANNIC ALLOYS. The details of the Cheoplastic process have been given in their origi- nal form, with few modifications. These have been adopted and im- proved upon in the vulcanite manipulations, as Avill be shown in the next chapter. The cheoplastic metal is the pioneer of the numerous alloys of Tin (stannum) which are now claiming the attention of the profession as substitutes for vulcanite. We have elsewhere spoken of the necessity of testing all such alloys in the crucible of "' practice." We shall mention only twro: those of Dr. B. Wood, and that of Dr. H. Weston. The first, because, next to the cheoplastic metal, they have been longest known to the profession, particularly those alloys adapted to the filling of teeth. The last, because it is very strong, Aoavs Avell, and, in the short time it has been observed by us, retains its color Avell. Of the composition of Dr. Weston's alloy, AATe know nothing beyond an assurance that it contains no copper or lead. It may be better than any of its competitors, closely resembling it; but, in ignorance of the formulas of any of them, we can only say what, perhaps, if we knew these formulas, we might still say — submit to the test of experience that which seems to be the best. Dr. Wood's alloys are the result of an elaborate series of very careful experiments made some ten years ago. His plate-alloys consist mainly, perhaps altogether, of tin and cadmium : they vary in fusibility, hardness, and rigidity, but are nearly, if not all, more fusible than Weston's metal. The following instruc- tions, in connection with Avhat have been given for cheoplastic work and Avhat remain to be given for vulcanite, will be a sufficient guide in the construction of plates made of Wood's, Weston's, or any other Stannic alloy. Teeth for rubber-work are best suited for this, Avith the folloAving pre- cautions : First: Grind off the thin upper edge of gum teeth or sec- tions : the anterior band is useful in rubber, and does no harm; if of STANNIC ALLOYS. 657 metal, it is apt to crack the block, and is unnecessary, as teeth are rather more firmly set in metal than in rubber; hence, no metal should overlap the upper edge of the gum. Secondly: In jointing blocks, do it as squarely as possible; if merely the edges of gum touch; the slight contraction of the alloy may cause them to scale or break. If, hoAvever from accident or necessity, this last kind of joint occurs, do as in sol- dering blocks to gold plate—place a thin piece of paper in the joint, before securing it to the wax-plate. Before drying the flasks, this slight space caused by the paper may be closed Avith plaster and soluble glass, to prevent metal from running in and making a metallic seam on the front of the block. Thirdly : Be careful to cover the pins Avith the Avax which gives shape to the metal, so that in finishing up the latter they will not be exposed. Instead of the cheoplastic matrix, the vulcanite flask (Fig. 312) may Fig. 312. be used, by filing out at the back a central opening and tAvo small side openings, corresponding to the gate and vents. But this does not give sufficient length of gate; and there is occasionally a failure of the plate in such flasks, from want of the force given by a larger head of metal. Hence, a much better flask is one recently made for Weston's metal, shaped like the above, except that it extends about tAvo inches further back; it also has two flanges in front, to alloAv it to stand firmly while the metal is being poured. It is very important to clamp it well before pouring, that the weight of fluid metal may not separate the halves of the flask; the slightest space will alloAv much or all the metal to flow out. Instead of the felspar used by Dr. Blandy, the plaster may be mixed Avith soapstone poAvder, pumice-poAvder, or clean Avhite sand. Asbestos would prevent shrinkage, but its fibres Avould interfere with the free fiWing of the batter. The same care in heating the flask is necessary as before stated, remembering that plaster confined in metal flasks takes longer to become dry. The flasks Avould be much im- proved by having a dozen or more holes drilled through ends and sides, to aid the escape of moisture; they could be temporarily closed 42 658 STANNIC ALLOYS. With wax while making the matrix. It is not safe to pour under less than three hours' drying; and this must never be done in direct con- tact with flame. Moisture is one of the products of combustion in all flame, and is largely absorbed by the plaster; hence plaster over flame can never be made perfectly dry, unless contained in some box, say of sheet-iron, excluding this vapor. Directions for heating, pouring, cooling off, and finishing are the same as given for cheoplastic work. We have seen pieces made of Weston's alloy which, after cutting off the gate and vents, were ready for the emery-cloth and brush-wheels. This result can be uniformly secured by care in shaping the wax and proper attention to tempera- ture in pouring. These alloys have a slight shrinkage, not sufficient to break blocks or chip the edges, if the directions above given are observed. The slight shrinkage gives these plates an advantage over vulcanite, in point of adaptation. Directions for repairs are the same as in the cheoplastic metal. It is also recommended to mend a broken tooth by investing as for gold soldering; then dry the piece, use muriate of zinc for aflux, and solder with blow-pipe or soldering-iron. After melting one-half the pieces and disfiguring the half of the re- mainder, it will probably be concluded that the seemingly more tedious process is the shortest. Still, we do not object to trial of the blow-pipe and soldering-iron; experience is the best of all teachers, perhaps because she enforces her teachings by such hard blows. The strength of the Wood or Weston metal permits its use for par- tial pieces, and allows stays to be formed on the plate; but full clasps cannot be made, because alloys of this class are not sufficiently elastic. The form of such plates will be discussed in the next chapter. In pre- paring the above directions, Ave have discarded some innovations upon Dr. Blandy's process, as being anything but improvements: such, for in- stance, as the recommendation to heat to 210°, or, "so that it can hardly be held in the hand," a flask containing teeth on to which a metal is to be suddenly poured at a temperature of 440°. This temperature may be quite sufficient, however, for some of Dr. Wood's alloys. The safest rule in all cases, except for repairs, is to heat up to the fusion- point of the alloy. As an offset to this error, we notice a good sugges- tion for removing small remnants of wax by washing out with hot water. It has an advantage over the plan of allowing the hot dry plaster to absorb the wax, in permitting examination of the pins and joints, and allowing closure of front joints with plaster; also, by ena- bling the mould to be thoroughly cleansed just before closing, it pre- vents the accidental retention of small particles of plaster, which may interfere with the flow of the metal. ALUMINUM AVORK. 659 ALUMINUM WORK. In answer to the question constantly asked by students whether aluminum or aluminium is correct, we offer the following explanation of the spelling adopted at the head of this section: This metal is in nearly all Avorks on chemistry called Aluminium, making it similar in termination to twenty-three other metallic bases discovered by modern science, and known by Latinized names ending in ium. None of these, however, have any practical value in the Arts as metals, except Cadmium, Magnesium, Palladium, Rhodium, and Iridium. The last three names are taken from classical Latin, the first two are Latinized from Cadmeia and Magnesia. These five metals, therefore, we would leave with their chemical terminations unchanged ; the first tAvo for euphony, the last three out of respect for antiquity. But Ave prefer the termination um for the metallic base of alumina for three reasons : First, chemical nomenclature does not demand ium, since Molybdenum, Platinum, Arsenicum, and all the metals known to the ancients end in um except Mercurium; secondly, the same change Avhich makes cad- mium and magnesium from cadmeia and magnesia, makes platinum and aluminum from platina and alumina; thirdly, because this ending is unifcrm with Aurum, Platinum, Argentum, Cuprum, Zincum, and Stannum, with which useful group of metals it has physical properties in common, rather than Avith the larger group of metallic bases, known only in the chemical laboratory. Sir Humphry Davy inferred, from his discovery of sodium and potassium, that alumina Avas the oxide of a metallic base. This con- jectural metal, named Aluminium, Avas subsequently discovered by Wohler, but remained for more than tAventy years a mere chemical curiosity, until, in 1854, St. Clair Deville succeeded in manufacturing it in large ingots by the action of sodium upon the chloride of alumi- nium; but the cost of metallic sodium made this an expensive pro- cess. He subsequently obtained it by the action of chloride of potas- sium upon the once rare mineral Cryolite — an alumino-fluoride of sodium, large deposits of Avhich have been discovered in Greenland. All rocks, except limestones and some sandstones, contain alumina; and it enters largely into the composition of all clay and slate rocks; hence, next to oxygen, Avhich constitutes one-half of the globe, and silicon, which forms one-fourth, alumina is the most universally dif- fused of all metallic oxides, and aluminum is the most abundant of all metals. The vast beds of iron-ore become insignificant compared Avith the ore-beds of aluminum. As iron is iioav the most useful as well as the most abundant of all metals, it may not be unreasonable to antici- pate a time when the extent and variety of uses to which aluminum 660 ALUMINUM WORK. will one day be applied shall be proportioned to the vastness of its ore- beds. The present use of aluminum, in dentistry and in the arts gen- erally, bears a small proportion to its future use, when its properties shall become developed, the manner of working it better understood, its metallurgy simplified, and its relations to other metals ascertained by experiment. Its valuable qualities now knoAvn, and its history during the sixteen years just past, go far to justify these expectations. Wre shall give a brief summary of the present state of knowledge of aluminum. It is the lightest metal known except magnesium (excepting also, of course, sodium and potassium); its specific gravity is 2.56 for cast metal and 2.67 for hammered metal, about the Aveight of glass or por- celain. Its point of fusion is somewhere near 1000° Fahrenheit. It is malleable, laminable, and ductile in a high degree; has a hardness equal to silver and excels it in point of tenacity; is eight times better than iron as a conductor of electricity, being nearly equal to silver. Unlike silver, it wholly resists the action of sulphur, also of nitric acid, unless it is boiling. Sulphuric acid does not affect it, nor do the vegetable acids, as citric, oxalic, and tartaric. Its proper solvents are hydrochloric acid and chlorine. It is somewhat affected by the caustic alkalies, soda and potash; also, perhaps, by ammonia and quicklime. A solution of salt and vinegar is said to affect it, possibly due to a liberation of the chlorine in the salt. Its record of resistance to change by acid and alkali is a very fair one, and gives rise to the conjecture of possible impurity of metal, in explanation of the cases reported in which aluminum plates undergo change in the mouth. The conjecture is strengthened by the pecu- liarity of this change; it occurs in spots, seeming to indicate some local impurity or alloy, not by a general discoloration of the plate, such as we see on eighteen-carat gold, or silver, and on the stannic alloys. Hence we infer that a perfectly pure aluminum plate will probably resist the secretions of the mouth ; also that it is desirable to avoid placing in the mouth alloys of aluminum with zinc, tin, or cadmium; and that alloys with gold, silver, or platina will prove less valuable than the pure metal. The subject of aluminum alloys in connection Avith the mouth and as solders is an open field of inquiry, which is at this time being diligently explored by Drs. Keep, Starr, Franklin, and others: these researches may some day be croAvned with the discovery of an aluminum base-plate equal in all respects to gold plate, Avith the peculiar advantage of its remarkable lightness. Present experience is unfavorable to its poAver of resisting the buccal secretions. Aluminum plates are swaged, teeth backed and soldered by the blow-pipe, just as in gold work. The best solder for this purpose is ALUMINUM WORK. 661 probably Dr. Starr's, containing seven parts aluminum to one of pure tin. Soldering is also done Avith a copper soldering-tool similar to that used by tinners; sometimes by the combined action of both But the results as yet reached, in the experiment of soldering aluminum, do not justify us in recommending this form of plate; hence Ave shall not give any description of the processes referred to, although esteeming them highly as experiments. The swaging of aluminum is done just as in case of gold or platinum, except that frequent annealing is neces- sary. The annealing must be done Avith extreme care, since the fusion- point of the metal is so little above red heat that the slightest excess of heat Avill Avarp, blister, or melt the plate. The extreme lightness of this metal permits the use of a plate tAvo or three times the thick- ness of gold plate; hence aluminum plates may be the very strongest that can be made in any given case. The best method yet proposed for attaching the teeth to such a plate is by vulcanite, the details of which process Avill be given in the next chapter. It is a peculiarity of pure aluminum that vulcanized rubber adheres to it with great tenacity. A set of Avell-chosen block teeth, skilfully arranged, and secured to an accurately fitting aluminum plate, may safely be offered to the most fastidious and critical patient. It has, moreover, the great advantage that " sixty-minute " dentists will not care to imitate work which takes " several" hours to do even passably Avell. Another form of aluminum work, and that which has led to the present classification of this metal under the head of Plastic Avork, is the moulded or cast aluminum plate. Experiments in this direction have been made during the past ten years. None, however, seem to us to have been conducted with such care as those of the late Dr. James B. Bean, of Baltimore, who perished under an avalanche, in the summer of 1870, Avhilst ascending Mont Blanc. Dr. Bean's inventive ingenuity and remarkable dexterity are dis- played in his well known "Interdental Splint" for fractures of the jaw; also in the apparatus hereafter described, as well as in many valuable suggestions in dental mechanics. In placing the "aluminum process" of our lamented friend before the reader, we shall take the liberty of entirely remodelling his paper now before us, omitting details already given common to other Avork; avoiding also that minuteness of detail, which, however desirable in a special pamphlet of " Instructions," is out of place in a general text-book; aiming to present such a condensed statement of the process as will best display its distinguishing merits. We shall also omit certain points, as to the value of which Dr. Bean had expressed to us some doubts, and shall make several modifications, which, in our last conversation with him, were acknowledged to be improvements. 662 CAST ALUMINUM PLATES. Dr. Bean's Process. — The details of this process should be classified in* order to get a clear idea of the difficulties to be overcome, and the ingenious devices by Avhich this is accomplished. Dr. Bean's earlier experiments demonstrated the inevitable cracking of block Avork in arty attempt to cast the aluminum in direct contact with the teeth; hence the plate is first made fitting all the irregularities of the blocks; the teeth are then slightly changed to suit the contracted size of the plate. The contraction of aluminum is so considerable that it inter- feres with correct adaptation of the plate in many cases; hence a plaster mould is taken and a second model made, so as to give three expansions of plaster, as an offset to this contraction. The lightness and sluggish flow of aluminum is another difficulty; this is overcome by the height of the conduit, and by the preparatory injection of gas or hydrogen into the matrix, Avith a view to exclude the oxygen of the air, supposed by Dr. Bean to interfere with the perfect flow of this metal. The processes peculiar to Dr. Bean's method are 1. The construction of sectional model and mould; 2. The manner of making the matrix, arranging the flask, and pouring the aluminum; 3. The mode of attach- ing the teeth to the plate. These will be minutely described ; but of other operations, such as the impression, articulation, grinding of teeth, and finishing, only so much of his description Avill be given as is pecu- liar to this method, or may contain some valuable suggestion not before mentioned. In taking impressions for full or for partial cases, Dr. Bean always used plaster in a brass cup, swaged for each case, and coated with cot- ton fibre as described in the chapter on impressions. In place of the band, there mentioned crossing the plate, he often used a stout wire, grasping it Avith pliers or forceps, if more force Avas necessary in remov- ing the impression than could be conveniently exerted by the fingers. In partial cases he found that the cotton fibre prevented the total sepa- ration of pieces necessarily broken, and made their readjustment more easy. The impression is partly dried, then varnished and oiled; it is then ready for making the first plaster model. The impression cup is carefully surround- ed with a narroAV strip of sheet AArax, (Fig. 313,) softened and tacked to the edge by the aid of a hot Avax-knife. In loAver cases, this rim, on the inside, should cross from ridge to ridge; in partial cases, it should fill the spaces corresponding to the natural teeth. The impression is then filled, turned down CAST ALUMINUM PLATES. 663 upon the remaining batter on the plaster-table, and moulded into shape with the spatula; then trimmed with the knife as usual, with slightly flaring sides. (See Figs. 315, 318, and 319.) Another method is to surround the impression with putty, clay, or paper-pulp, as hereto- fore described, and set upon this a tin ring or lead band, (Fig. 314,) curved so as to give proper flare to the sides of the model; then pour FlG- 314- the plaster, remove the rim, detach the impression, and trim as before. In deep upper arches, and in all lower cases, the model should be made in two halves, as described on page 553, by means of the leaden septum (Fig. 226) ; otherwise the expansion of the central portion (c, d,f, Figs. 318 and 319) of the plaster mould will be apt to break the model. It is important that the plaster of this model, and of the mould next to be made upon it, shall have as much expansion as possible. Dr. Bean's experience was that thin plaster expands more than a thick batter, and quick plaster more than the slow-setting: our own expe- rience is that coarse-grained plaster makes a stronger and more expan- sive model than the fine-grained variety. If, therefore, model and mould are made of coarse, quick-setting plaster made into a thin batter, the extreme limit of expansion will be secured. The model is to be dried sufficiently for varnishing; then coated Avith shellac or sandarach varnish until a glazed surface is given; then well oiled, and placed in position (Fig. 315) for making upon it the plaster mould. This must be made in sections, otherwise mould and model cannot be Fig. 315. separated; for the plaster mould will not in any case yield like the sand mould, used in swaged AAfork. Before making this mould, Dr. Bean directs the formation of the prominence for the vacuum cavity, expressing himself as " decidedly in favor of shalloAV cavi- ties, and some of our best operators are recommending none at all. If this principle holds good in other kinds of work, it is still more advisable in aluminum, on account of the superior fit. The principal advantage of the cavity in a permanent set is in easily securing a firm adhesion at first, consequently giving to the patient satisfaction at once. In temporary sets, the piece is often held firmly by the cavity, long after an amount of absorption has taken place, that would entirely prevent 664 CAST ALUMINUM PLATES. the plate from being sustained Avithout such aid. When an air-cham- ber must be used, take a piece of sheet-lead, which should seldom be thicker than one-thirtieth of an inch, or about No. 22, Stubbs' gauge. Cut this to proper size and shape, and press it into place on the model by the fingers, and with the aid of a blunt-pointed burnisher." The prominence may also be formed by cutting a corresponding depression in the mould (see /, Fig. 317) ; this we think the better plan, when the model is made in tAvo parts. As to the propriety of using the cavity at all, our views are elsewhere fully given; a very shallow cavity in plastic work is the least objectionable form of the vacuum cavity. For making the mould, the model is surrounded by a flaring leaden band (Fig. 314) or tin ring, curved as in Figs. 316 and 317; if of tin, Fig. 316. Fig. 317. it must be closed with a clamp (not soldered), so as to permit free expansion of the plaster. The centre of the model, to the top of the alveolar ridge, is filled with a mass of soft clay or putty, shaped as shown in the sectional vieAvs, Fig. 318, cfd, and Fig. 319,/. The space e gh (Figs. 316, 318, and 319; is then filled Avith plaster, placing at the front and back three tin-foil septa (, XTB DISK A $S: $7 WITH THEIR TREATMENT; INCLUDING THE GOUTY HEART. By J. MILNER FOTHERGILL, M.D., Author of "The Practitioner's Handbook of Treatment," "The Antagonism of Therapeutic Agents," etc. OCTAVO. PRICE, $3.50. " It is the best, as well as the most recent work on the subject in the English language."— Medical Press and Circular. " To many an earnest student it will prove a light in darkness; to many a practitioner cast down with a sense of his powerlessness to cope with the rout and demoralization of Nature's forces, a present help in time of trouble."—Philadelphia Medical Times. "The work throughout is a masterpiece of graphic, lucid writing, full of good sound teaching, which will be appreciated alike by the practitioner and the student."—Student's Journal. " Dr. Fothergill's intention has rather been to present the natural history of heart disease as a series of vivid pictures before the imagination of the reader, and to carry the doctor as a living actor into the scene. For this purpose he has properly chosen to use academic detail, not ex- haustively, butas a means to this end, and he has brilliantly succeeded."—Westminster Review. " The most interesting chapter is undoubtedly that on the gouty heart, a subject which Dr. Fothergill has specially studied, and on which he entertains views such as are likely, we think, to be generally accepted by clinical physicians, although they have not before been stated, so far as we are aware, with the same breadth of view and extended illustration."—British Med. Journal. " Dr. Fothergill's remarks on rest, on proper blood nutrition in heart disease, on the treat- ment of the sequelae of it, and on the actions of special medicine, all indicate that, in studying the pathology of heart disease, he has earnestly kept in view the best means of mitigating suf- fering and of prolonging life."—The Lancet. LINDSAY & BLAKISTON, Publishers, PHILADELPHIA. AMERICAN HEALTH PRIMERS. Edited by W. W. KEEN, M. D., Fellow of the College of Physicians of Philadelphia; Surgeon to St. Mary's Hospital, etc. This series nf American Health Primers is prepared to diffuse as widely and cheaply as possible, among all classes, a knowledge of the elementary facts of Preventive Medicine, and the bearings and applications of the latest and best researches in every branch of Medical and Hygienic Science. They are not intended (save incidentally) to assist in curing disease, but to teach people how to take care of themselves, their children, pupils, employees, etc. They are written from an American standpoint, with especial reference to our Climate, Sanitary Le^i Aavaan tvnouvn snidiqsw do Aavaan tvnouvn snidiqsw do Aavaan tvnouvn ► A RARY OF MEDICINE ' 4 NATIONAL LIBRARY OF MEDICINE NATIONAL LIBRARY OF MEDICINE > Aavaan tvnouvn ► -g O snidiqsw do Aavaan tvnouvn snidiqsw so Aavaan tvnouvn X RARY OF MEDICINE NATIONAL LIBRARY OF MEDICINE NATIONAL LIBRARY OF MEDICINE i Aavaan tvnouvn SNiDiasw do Aavaan tvnouvn snidiosw do Aavaan tvnouvn / M^l «\ I /MM I Air x .f ^ y \ I gfy IL ICINE NATIONAL LIBRARY OF MEDICINE NATIONAL LIBRARY OF MEDICINE NATIONAL LIBRARY OF MEDI ouvn SNiDiasw so Aavaan tvnouvn snidiosw do Aavaan tvnouvn snidiosw so Aavaan tvnc >ICINE NATIONAL LIBRARY OF MEDICINE " NATIONAL LIBRARY OF MEDICINE NATIONAL LIBRARY OF MEDI jouvn snidiqsw so Aavaan tvnouvn snidiqsw so Aavaan tvnouvn snidiqsw so Aavaan tvnc 3ICINE NATIONAL LIBRARY OF MEDICINE NATIONAL LIBRARY OF MEDICINE NATIONAL LIBRARY OF MEDI •jouvn snidiqsw do Aavaan tvnouvn snidiqsw do Aavaan TVNOUVN snidiqsw so Aavaan TVN( DICINE NATIONAL LIBRARY OF MEDICINE NATIONAL LIBRARY OF MEDICINE NATIONAL LIBRARY OF MED jouvn snidiqsw so Aavaan tvnouvn SNiDiasw so Aavaan tvnouvn snidiosw so Aavaan tvn< I II )ICINE NATIONAL LIBRARY OF MEDICINE NATIONAL LIBRARY OF MEDICINE NATIONAL LIBRARY OF MED W l - »«.* OUVN 3NIDIQ3W dO Aavl '(wfUjOjlVN 3NIDI03W dO AavaaiT TVNOUVN 3NIDI03W so Aavaan TVN< NLM031926483