' COMPLIMENTS OF THE AUTHOR. 
Chloride of Methyl. 
BY M. L. RHEIN, M.D., D.D.S., NEW YORK, N. Y. 
(Reprinted from the Dental Review for September, 1889.) CHLORIDE OF METHYL. 
By M. L. Rhein, M.D., D.D.S., New York, N. Y. 
The dental profession has long been in search of some practical 
means of alleviating the intense suffering which is often inflicted 
upon patients while preparing teeth for filling. We have now at 
our disposal numerous medicaments, each of which has its advo- 
cates. Creosote, carbolic acid, potassa, glycerine, cocaine, chloride 
of zinc, and various other therapeutic agents and combinations of 
remedies, are in daily use to accomplish this purpose. Some advo- 
cate the use of the sharpest and swiftest revolving burs; others of 
intense heat; and again others of extreme cold. All these agents 
have obtained their reputation by producing a more or less com- 
plete stage of anaesthesia of the terminal ends of the nerve fibrillae, 
the results varying in different individuals and under different con- 
ditions and surroundings. 
When we consider the density of the dentinal structure, the 
shortness of the period that a therapeutic agent remains in contact 
with the dentine, and the rapidity of the return of sensibility to the 
parts ; we are forced to the conclusion that but rarely is there any 
absorption of a remedy, and consequently no persistent benefit is 
derived from it. The vain efforts of so many to procure good re- 
sults by the use of cocaine alone, and the frequent success when 
this remedy is combined with others, is well known to all. If no 
distinctively therapeutic benefit is gained from these remedies, how 
then do they so often produce the desired results ? The only rea- 
sonable conclusion is that local anaesthesia of the dentine as ob- 
tained at the present time, under any known process, is the result 
of counter-irritation. 2 
Of all the counter-irritants, extreme heat and cold are certainly 
the most effective. The late revival of the use of the various ethers 
.in the form of spray, for the production of intense cold, indicates 
that this method of obtunding sensibility is held in esteem by a 
portion of the profession. Although very successful in the applica- 
tion of the ether spray, I was deeply chagrined by the numerous 
disadvantages attending its use, chiefly the length of time required 
to produce the desired intensity of cold, and the consequent un- 
pleasantness resulting from the volatilization of so much ether. 
About this time, while attending to the teeth of Dr. G.W. Jacoby, 
President of the New York Neurological Society, I employed hydro- 
chlorate of cocaine to produce the desired anaesthesia in the re- 
moval of some gum tissue which overlapped a third molar. This 
led to a conversation about local anaesthesia, and I learned that he 
had obtained remarkable success in the treatment of sciatica and 
all forms of neuralgia by the use of intense cold produced by chlo- 
ride of methyl, and he referred me to an article by himself, entitled 
" Treatment of Neuralgias by Means of Intense Cold." 
Chloride of Methyl was discovered in 1834. Its production 
was at first too complicated and expensive to admit of its general 
use. It was made by heating a mixture of sulphuric acid, methylic 
alcohol and sea salt. A very cheap process has been invented by 
C. Vincent, of France, and all the Chloride of Methyl used in that 
country is manufactured near Paris under his patent. He takes 
the remnants of beets used in the manufacture of sugar, and 
extracts from these the chlorate of tri-methylamine, which being 
subjected to a sufficient degree of heat produces the Chloride of 
Methyl. 
At ordinary temperature this is a colorless gas of slightly 
etherous odor and sweetish taste. It boils at 230 C. Above this 
temperature it can be kept in a liquid state only by keeping it 
under high pressure in very strong air tight vessels. When relieved 
from pressure it returns at once to a gaseous state, producing a 
reduction of temperature from -230 C. to as low as -400 C. 
Malassez and Ranvier have for some years employed this prin- 
ciple of artificial refrigeration for freezing histological specimens. 
The commercial value of Chloride of Methyl consists principally 
in its use for the extraction of perfume. 3 
Ddbove is entitled to the credit of having first used Chloride of 
Methyl medicinally. The first patient on whom he used it had 
been suffering from a severe attack of sciatica for the cure of which 
various treatments had been employed in vain. Of this case 
D^bove writes as follows : " I passed the jet of Chloride of Methyl 
over the entire painful service, from the hip to the external malleo- 
lus. A minute later the patient, who until then could not put his 
foot to the ground, walked around the ward without limping." Up 
to 1885 he had used the Chloride of Methyl in over one hundred 
cases. Since then numerous successful results have been published 
mainly by French physicians. In 1884 R. D. Santelli published the 
results of thirty successful cases treated by this means. Dr. Olive, 
of Nantez, describes four successful cases. 
Before various meetings of the Soci6t£ M^dicale des Hospitaux 
various successful experiences with this remedy were detailed by 
Rendu, Bucquoy, Sevestre, Legroux, Tenesson, and F. Rouillon, 
of whom the last detailed five cases of trigeminal neuralgia of from 
three months to fifteen years duration, in two of which both nerve- 
stretching and re-section had been performed unsuccessfully. Four 
of these cases were cured and one relieved. 
A. Peyronnet de Lafonvielle writes of eight cases of trigeminal 
neuralgia of long duration which were relieved after several appli- 
cations. In the article by Dr. G. W. Jacoby on this subject, pre- 
viously referred to, he mentions five cases of tri-geminal neuralgia 
treated by this method. He says: "In all five cases the pain was 
entirely relieved after the first application. In one of the fresh 
cases there was no return of the pain. In two others the pain re- 
turned and a second application was made, with the result of reliev- 
ing the pain again. In these also there has been no return. One 
of the old cases was so much ameliorated after four applications 
that he discontinued treatment, although not entirely well. In the 
fifth case I was able to obtain relief after each application and al- 
though six applications were made, there is no sign of permanent 
improvement. My general impression from this brief experience 
is, that we have in the Chloride of Methyl a reliable analgesic, which 
does not effect the general condition of the patient, and that it is in- 
valuable in the treatment of neuralgias for the immediate relief of 
severe pain." 4 
In the first successful experiments, the substance was placed in 
an ordinary thick glass syphon, provided with an attachment piece 
by means of which a fine spray could be produced. Numerous ex- 
plosions of these syphons caused their abandonment. The appara- 
tus as at present constructed consists of a copper cylinder having 
the capacity of about one litre. Above the cylinder is a strong screw 
which when fastened down prevents the escape of the methyl. When 
this screw is loosened the fluid escapes through a lateral opening 
into a smaller brass tube through the mouth of which it comes in 
the form of a fine spray which can be regulated in the most delicate 
manner by means of a micrometer screw. The brass adjustment is 
not well calculated for reaching the distal aspects of the posterior 
teeth, but does very well for other surfaces. I have designed for 
these posterior surfaces a special attachment which overcomes this 
difficulty. There are three methods of application, as follows: first, 
the direct application of the spray. Second, the glycerine method 
of Bardet. The part being first covered with glycerine the spray 
is directed against it, and the frozen glycerine is supposed to pro- 
duce a more intense degree of cold. Third, the "stypage method" 
of Dr. Bailly, which consists in making a tampon of prepared cot 
ton which ought to be enveloped in fine silk; (the cotton can be 
covered with glycerine if desired), and while being held with a pair 
of dressing forceps, deluged with spray and then immediately 
pressed against the painful point. The intensity of cold obtained by 
this method depends upon the amount of pressure with which it is 
applied against the surface, and it is supposed will produce a more 
intense cold than either of the other methods. It requires, however, 
too large a tampon to make it practicable in average sized cavities 
of teeth. This is the method, however, which seems to produce 
the best results in the various forms of facial neuralgia. I have 
also found it invaluable for producing relief and curing incipient 
pulpitis by means of the intense degree of counter irritation which 
it produces. The tampon should always be pressed against the 
point where the seat of the pain is located, but care must be taken 
not to hold it too long in position, as there is danger of its produc- 
ing a blister or eschar; with a little care this can always be avoided. 
The tissue becomes pale and hard following the application and 
there is a momentary burning sensation followed by an immediate 5 
relief from pain. In numerous cases the pain returns again and 
often it requires three or four successive applications to obtain a 
permanent cure. There are, however, forms of deep seated neural- 
gia, which while they are temporarily relieved, occur again at in- 
tervals. Jacoby's explanation is, that when the neuralgia is situated 
in the nervi nervorum (as it most generally is) the severe cold en- 
tirely destroys or at any rate completely paralyzes these nerve fila- 
ments, but when the seat of pain is in the nerve fiber itself, being 
not so accessible, the pain returns. 
My first experience with the chloride of methyl occurred in 
February last. Mr. M., a professional vocalist, was sent to me 
for relief from severe neuralgic pain. A dentist in extracting 
the right inferior third molar had removed all of the process and a 
sufficient amount of the maxilla to expose a portion of the inferior 
dental nerve ; cocaine produced a short respite ; but the patient 
returned soon after with a recurrence of the pain and an agonizing 
appeal for something to be done for his relief so that he would be 
enabled to sing that evening. In my dilemma I thought of the 
chloride of methyl, and having sent for Dr. Jacoby's cylinder I used 
a tampon which resulted in an entire dissipation of the patient's 
suffering. 
Early in March I procured from McKesson & Robbins a cylin- 
der filled with chloride of methyl which they import from Paris, 
and determined to keep a record of my observations. I will detail 
a few of the most interesting cases : 
March 5. Mrs. L. presented herself to have the posterior 
approximate and crown surfaces of the left superior second bicuspid 
and the anterior approximate and crown surfaces of the left 
superior first molar filled. Within the past two or three weeks she 
had a number of cavities filled without much pain. She was not of 
the nervous class that suffers from the slightest touch of an instru- 
ment. The excavation of these cavities proved to be excruciat- 
ingly painful ; they were deep but did not reach the pulp. The 
rubber dam having being applied and the cavities dried, the cylin- 
der of methyl being held in the left hand and the screw having been 
loosened, the nozzle was pointed as near the cavity as possible and 
with the right hand the micrometer screw was opened for about 
fifteen seconds. After this application the cavities were thoroughly 6 
prepared by means of large engine burs and hand instruments 
without causing the slightest pain ; the patient complained of a 
momentary sensation when the spray first struck the tooth's sur- 
face, but was delighted with the result. No bad effects have been 
noticed up to the present time, and on July 10th, it was found that 
the tooth responded perfectly to the cold and heat, showing that 
the pulp had not been injured. 
March 18. Mrs. K. had a large cavity in the left inferior second 
molar to be filled; she was of that intense nervous tempera- 
ment, that dreads every movement the operator makes. Her teeth 
had been under my charge for the past eight years, and I knew by 
bitter experience that operating for her was alike agonizing to den- 
tist as well as patient. She was very skeptical, and my first 
application of the spray to the tooth was not very effective. This 
I believe was due to using an insufficient amount of methyl. A 
second application produced complete local anaesthesia. 
March 21st. Mr. P., aged eighteen, a very nervous young man, 
and difficult to operate for; the right superior second bicuspid had 
a small cavity on the posterior approximate surface which was very 
sensitive. The application of the chloride of methyl produced com- 
plete local anaesthesia which lasted about two and a half minutes. 
It required two applications to prepare the cavity. 
April 3d. Miss C. presented herself suffering with a toothache 
so severe as to cause an intense neuralgic headache. The second 
superior right molar had a large cavity reaching almost to the pulp; 
it was excruciatingly sensitive to the touch; the application of the 
methyl produced a momentary degree of pain which was very in- 
tense, but in turn this was followed by complete local anaesthesia 
and an immediate disappearance of the headache. Sensation re- 
turned before the cavity was entirely prepared, and a second appli- 
cation was required to complete the operation. A temporary oxy- 
phosphate filling was inserted, and there was no recurrence of 
pain. 
April 19. Miss S.had cavities on the anterior approximate sur- 
face of the second right superior bicuspid and the posterior ap- 
proximate surface of the first right superior bicuspid. They were 
acutely sensitive to the touch, but an application of the methyl 
produced complete local anaesthesia and a temporary stopping of 7 
gutta-percha was inserted. On May 6th, after removing the stop- 
ping, the cavities were found to be so acutely sensitive that another 
application was made, the result being that gold fillings were in- 
serted without the patient having any appreciable sensation of the 
operation. 
April 22d. Miss F., of nervous temperament, had a cavity on 
the posterior approximate surface of the second inferior left molar; 
it was impossible to obtain direct access to the cavity wuth the 
nozzle of the spray apparatus, as then constructed, but an applica- 
tion was made as well as possible. It seemed only to increase the 
pain, and a second and third application produced no better result. 
The patient endured the pain, and had the cavity filled, but com- 
plained of intense suffering from the tooth during the following two 
nights, when the pain disappeared. On recent examination the 
pulp was found to respond perfectly to heat and cold. 
April 26th. Mrs. F. had filled with copper amalgam on the day 
previous a cavity on the posterior approximate surface of the second 
superior left molar. The cavity was very deep, reaching under the 
gum, and though very sensitive no application was made on ac- 
count of its inaccessibility. She had suffered all night with pain 
from the offending tooth, and there were present all the symptoms 
of incipient pulpitis. A tampon of cotton having been covered 
with glycerine and thoroughly saturated with chloride of methyl, 
was pressed firmly on the gum at a point where the apices of the 
buccal roots were supposed to be; immediate relief ensued. In 
about five minutes pain returned and again disappeared after 
another application. After longer intervals there was a recurrence 
of a lesser amount of pain, but after the fourth application the 
pain disappeared not to return. 
April 27th. Miss S. had the first inferior right molar filled 
with copper amalgam six months previously. It was very painful 
at the time, and has always remained sensitive to cold and heat, 
which symptoms have increased in severity during the past week so 
markedly as to indicate approaching death of the pulp. After ap- 
plying the rubber dam, the tooth was thoroughly saturated with the 
methyl spray, which produced immediate relief from all pain. With 
a recurrence of pain, four separate applications were made, after 
which the rubber dam was removed. The patient experienced 8 
complete relief for about twenty minutes, when, according to her 
statement, the pain returned in a more intense form than had yet 
been experienced, and seemed proof against all counter-irritant 
treatment. An opening was then made through the filling into the 
pulp chamber, and the pulp removed. 
The above detailed descriptions will give an idea of the average 
results obtained. Out of seventy-six cases, four alone were found 
to be proof against the action of the methyl, and two of these are 
believed to have been due to the inaccessibility of the cavities. 
In conclusion, it is believed that, in the chloride of methyl, will 
be found a valuable addition to our therapeutic armamentarium. 
It appears to be the most reliable local anaesthetic yet introduced 
for preparing teeth for filling, though it is advised not to use it in a 
cavity near the pulp. It is wonderfully effective in affording imme- 
diate relief in all forms of neuralgia, and permanent cure in a ma- 
jority of cases. Lastly, it has been found to be remarkably potent in 
the cure of incipient pulpitis, and though its application is always 
more or less painful, it seems to be generally preferred by patients 
to the pain from which they have been suffering. 
(104 East Fifty-eighth Street.)