CHAPTER IV.

The Use of Anæsthetics during Extraction of the Teeth.

The anæsthetics used during the extraction of teeth may be divided into two classes, viz.:--general and local. It is not proposed to make any allusion to the methods of administering general anæsthetics, as they hardly fall within the scope of this volume. There are, however, a few points which the operator should bear in mind when employing them and which may with advantage be briefly dwelt upon, but before considering these, a word or two may not be out of place with regard to the choice of the anæsthetic. In dental practice three agents are generally used, nitrous oxide alone or in combination with air or oxygen, ether and chloroform.

In the very large majority of dental operations nitrous oxide is to be preferred to ether and chloroform, and possesses the great advantage over them of being practically safe. In addition, the administration of nitrous oxide occupies a shorter period, and the recovery is rapid and complete. Within the last few years, combinations of nitrous oxide with oxygen and with air have been introduced by Dr. Hewitt and Mr. Rowell respectively, and both combinations possess advantages over nitrous oxide used alone.

_The advantages of nitrous oxide and oxygen over nitrous oxide alone are_:--

(1) The anæsthesia is quieter.

(2) The mucous membranes of the mouth do not swell to the same extent, and the operator therefore gains a clearer view of the tooth.

(3) The period of anæsthesia is lengthened, perhaps by only a few seconds, but the quieter condition of the patient assists indirectly in prolonging the period for operating.

_The advantages of nitrous oxide with air over nitrous oxide alone_ are somewhat similar to those of nitrous oxide and oxygen, though less marked.

_For operations requiring a long anæsthesia_, such as the extraction of a difficult third molar, ether should be used, the administration being commenced with nitrous oxide. In such cases many operators prefer to use chloroform, but the regular employment of this agent in dental surgery is to be severely condemned, and the cases are rare indeed in which its use is called for. A most careful inquiry into this important subject has been made by Dr. Hewitt, and the results of his work were communicated in an exhaustive paper published in the _Journal of the British Dental Association_ for November, 1895, which is well worthy the perusal of all those who are in the habit of administering chloroform.

Whenever a general anæsthetic is given for the removal of teeth, two people should always be present, one to confine his attention solely to the administration of the anæsthetic, the other to the removal of the tooth, as it is impossible for one person to operate and at the same time to observe the condition of the patient during the anæsthetic period. This rule should be strictly adhered to.

For extraction under nitrous oxide, and also to a great extent under ether, the positions of the patients should differ but little if at all from those already advocated, with this exception, it is advisable not to have the head too far back. Before the administration of the anæsthetic is commenced, any removable artificial teeth that may be in the mouth should be taken out; the operator should decide exactly what he intends to do; at the same time it is well not to attempt too much and to avoid pricking the gum during the examination of any roots that it may be necessary to extract. The prop should be placed on sound firm teeth in such a position that the operator can work without being hindered by it, and a final view of the mouth should be taken. Where several teeth have to be extracted at one sitting, their order of removal should be decided upon before the operation is commenced, and if any particular tooth is causing pain, it should be extracted first. The order of removal should also as far as possible be arranged so that changes of instruments are reduced to a minimum. As a rule, lower teeth should be extracted before upper teeth, because if the latter are removed first, the blood may pass down and so obscure the lower ones. Roots should be removed before whole teeth for the same reason. Each tooth or root must be cleared from the mouth before any attempt is made to remove another except in cases where the gum is thoroughly adherent; under this condition the tooth or root may be left and freed from the gum when the patient has recovered. With teeth which have a liability to slip out from between the blades of the forceps, it is well as a precaution to keep a finger of the left hand behind the blades to prevent the tooth passing backwards should it slip out.

LOCAL ANÆSTHETICS.

(_a_) =Cocaine.=--The most efficacious of the local anæsthetics in use is cocaine. It is an alkaloid obtained from the dry leaves of Erythroxylon Coca, and in practice the hydrochlorate form is generally used. For the removal of teeth it is necessary to inject a solution of the drug into the tissues, a simple application to the gum being of little use. Cocaine has the reputation of not being thoroughly reliable in its action, but this in a great measure often arises from want of care in injecting it. Not more than half a grain should be injected for the removal of a tooth, and even then with people of feeble health, untoward symptoms may supervene.

_Mode of Employment._--A fresh solution of the drug should be made each time its use is called for, by dissolving a tabloid weighing half a grain in 5 minims of distilled water. Half of the solution should be injected into the gum on each side of the alveolus. The gum being such a dense tissue, the solution should be injected slowly, otherwise the bulk of it will escape by the side of the needle into the mouth. As there is always a tendency for this to happen even when the solution is slowly injected, it is well to keep a finger of the left hand pressed on the gum where the needle is inserted.

Speaking personally, I usually occupy about eight minutes over the injection, and wait for four or five minutes after its completion before operating. As a local anæsthetic I have generally found cocaine satisfactory, so far as its anæsthetic properties are concerned, but the occasional appearance of toxic symptoms, especially in those of feeble health, should not be lost sight of. Tropacocaine has been recommended as possessing the anæsthetic properties of cocaine without giving rise to toxic effects, but in practice I have not found these statements fully borne out.

_Toxic Effects._--The administration of cocaine, especially if given in large doses, may be followed by well-marked toxic effects of which the following are cited by Dr. Hewitt.[4]

“Headache; vertigo; pallor; a cold, moist skin; a feeble, slow, or rapid pulse, becoming imperceptible in grave cases; incoherence of speech; nausea; vomiting; unconsciousness; trismus and other muscular spasms; epileptiform attacks; dilated or unequal pupils; and disturbances of respiration, culminating in dyspnœa and asphyxia.” The treatment of cocaine poisoning should be directed first to restoring the circulation by the administration of a rapidly acting stimulant, such as sal-volatile, brandy, or the hypodermic injection of ether. The patient should be placed in the horizontal position, and the respiration watched for; should this tend to fail, artificial respiration must be immediately resorted to.

(_b_) =Freezing Agents.=--This group includes such preparations as _chloride of ethyl_, _coryl_ (a mixture of chloride of ethyl and chloride of methyl in such proportions that the mixture boils at 0° C.) and _anestile_. Generally speaking, the anæsthesia produced is by no means satisfactory, and to use them to the greatest advantage, attention must be given to the following points:--

(1) The gums must be well dried, and as far as possible all neighbouring regions, such as the cheeks or tongue, protected by napkins or other suitable material.

(2) The gums must be thoroughly frozen before commencing to operate.

(3) The extraction must be carried out as quickly as is consistent with thoroughness.

(4) If possible the spray should be continued during the operation.

(5) Too great a jet should not be used.

Freezing agents can be employed much better for front than for back teeth, in fact it is found at times difficult to freeze the gums at all satisfactorily at the back of the mouth.