This section is from the book "Dental Medicine. A Manual Of Dental Materia Medica And Therapeutics", by Ferdinand J. S. Gorgas. Also available from Amazon: Dental Medicine.
Dr. A. C. Gask recommends painting the palate with a five per cent. solution of cocaine for obtaining impressions of mouths which exhibit great intolerance to the introduction of all impression materials; also a 20 per cent. solution applied to the mucous membrane on cotton, for service in wedging and separating teeth, in forcing silk, etc., up in high conical edges, in removing portions of overhanging gum, in lancing abscesses, in treating alveolar pyorrhoea, in extirpation of pulps, and in the treatment of teeth very sensitive from periodontitis; also in the form of a 1/4 grain compressed tabloid placed in the cavity, to relieve the pain following extraction.
The dangers from the use of cocaine are enumerated as follows: Certain persons possess an idiosyncrasy to cocaine, which cannot be foreseen or entirely guarded against; it exerts its toxic effects upon the nervous centres and, secondarily, the heart; its evil effects are most liable in neurotic subjects; the danger in cocaine poisoning is mainly from paralysis of the heart, syncope; special care is necessary in "weak heart" and organic heart disease; many regard its subcutaneous administration as dangerous, and that it should be avoided; the use of the strongest solutions is dangerous and unnecessary; that it may be well to precede its use by the administration of alcohol or other cardiac stimulant, as is done with chloroform.
Patients of a sanguine temperament and in good health are the most favorable subjects in the use of cocaine; while the nervous, hysterical, and those exhibiting great dread of the impending operation, as well as pregnant women, may be regarded as unfavorable subjects. Great care should also be taken to prevent even the weakest solution of cocaine from running down into the fauces, and restorative agents should always be at hand.
Cocaine appears to be absorbed with extraordinary rapidity, and the stronger the solution which is locally applied, the greater the danger of toxic symptoms. The rapidity of the absorption varies in the different tissues, absorption occurring most rapidly through the conjunctiva, then through the nose, larynx, mouth and ear. A ten per cent. solution is sufficiently strong for most purposes, and is less dangerous than one of greater strength.
The treatment of cocaine poisoning consists of measures to rouse the heart, especially inhalations of the nitrite of amyl, and such restoratives as brandy, whiskey, aromatic spirits of ammonia, strychnine, atropine, digitalis, ether and chloroform (when convulsions are present), or five minims of carbonate of ammonia by injection. The hot baths, hot drinks, and hot sinapisms over the heart, and friction are often serviceable; also artificial respiration. M. Elroy recommends flagellation with wet towels, massage, and artificial respiration, if asphyxia threatens; inhalations of chloroform against tetanization of the respiratory muscles; where there is great pallor to provoke vasodilatation, and to diminish the encumberment of the central circulation by the inhalation of amyl nitrite. If these means prove ineffectual and deglutition is impossible, give hypodermic injections of caffein and of sulphuric ether (15, 30, even 45 minims). M. Chouppe recommends in addition the hypodermic injections of morphine, but only in the very outset, and as large as from one-half to five-eighths of a grain.
Efforts should be made to moderate the reflex excitability of the nervous system, sustain the heart, and reestablish the equilibrium of the blood-pressure.
Dr. Curtis recommends a preparation called volasem as an antidote to the effect of cocaine.
Cocaine is also employed in combination with arsenious acid for a pulp-devitalizing mixture. (See Arsenious Acid.) One grain of cocaine to one-eighth ounce of chloroform is employed for extirpating pulps without pain.
When combined with nitrate of silver, decomposition of the hydrochlorate occurs with the formation of an insoluble chloride of silver, and a corresponding change in the cocaine. If calomel and hydrochlorate of cocaine are rubbed together, chemical reaction begins. Added to mercuric oxide, an irritating instead of an anaesthetic action is produced, due to the formation of oxychloride of mercury.
H. Carlton Smith gives the following simple test: "To a solution of cocaine was added a few drops of ferric chloride; the iron was reduced as usual; then the addition of a single drop of stannous chloride produced a white precipitate. This disappeared upon shaking, but one or two more drops of the chloride of tin reproduced it, and this time it was permanent."
Vapocaine consists of a fifteen per cent solution of cocaine hydrochlorate in ethyl ether, and is employed as a dentinal anaesthetic. It is neutral to litmus paper and is the production of an ethereal solution of a cocaine salt. It is principally used as an obtundent for sensitive dentine, and it is claimed for it that as aqueous solutions of cocaine salts fail to penetrate the dentine, and the ethereal solution of cocaine alkaloid is deficient in anaesthetic property, an ethereal solution of a cocaine salt, besides possessing anaesthetic properties, will secure the maximum of anaesthesia with the use of a minimum amount of cocaine. Vapocaine possesses great penetrating power, which is due to the fact that the heat of the mouth vaporizes a portion of the ether, and drives the natural fluid of the tooth out of the tubuli, thus securing a rapid distribution of the remaining portion throughout the tooth structure. From this portion the ether is dissipated, leaving the cocaine salt distributed in minute subdivisions throughout the tubuli. The cocaine is then redissolved by the natural fluid of the tooth, securing a rapid and effective anaesthetic. By its use the natural moisture of the tooth is made to act as a solvent for the cocaine, thus obviating the delay which occurs when a watery solution of cocaine is allowed to diffuse throughout the tooth. The following is the method for using vapocaine: Apply the rubber dam and dry the cavity with hot air before applying vapocaine. Then place a piece of dry absorbent cotton in the cavity and drop the vapocaine on this until thoroughly saturated. Leave this in from two to five minutes, keeping the cotton saturated until ready for operation. It is preferable to cover the cotton with a piece of rubber dam in order to prevent the too rapid evaporation of the ether. Repeated applications of the vapocaine are made after a portion of the decayed dentine is first removed, and during this operation, and the dentinal tubuli being free, the vapocaine permeates the entire tooth structure. It requires a few minutes to produce a good result. It acts quickly in some teeth, and slowly in others. It is supposed to penetrate the dentinal tububli chiefly by thermal energy rather than by capillary attraction, the evaporation of the ether causing pressure, which drives the moisture out of the tubuli and forces the vapocaine in. The ether being evaporated by the heat of the mouth, a deposit of cocaine remains in the tubuli, and is then dissolved by the natural fluid of the tooth again filling the tubuli.