1st. The presence of the micro-organism.
2d. The existence of a suitable pabulum.
3d. A certain degree of moisture.
4th. A certain degree of warmth.
5th. A certain amount of oxygen or air.
6th. A lessening of the resisting power of the tissues affected, as compared with health.
All of these first five conditions are notoriously present in the mouth. That we do not oftener suffer from their effects is due to the absence of our sixth element, the lessening of the resistance of the tissues. Thus, in health, those organisms which flourish best in an acid secretion have their baneful activity held in check by the alkaline saliva as well as the resisting power of the dense enamel. But once let the alkalinity of the saliva be lessened, or changed to an acid reaction, or let ever so small an abrasion occur in the enamel, and the myriads of these agents find a foothold for starting the morbid train of symptoms. Similarly, even in the tissues themselves, the enamel, no less than the dentine, suffers from those predisposing causes of constitutional malnutrition, which are so important in their effect on the central cell, and which act in lessening the normal resistance of the periphery.
It would be a work of supererogation to trace the progressive course of caries and the mechanism of the production of pain through irritation of the pulp. But when we come to the question of treatment, the two main considerations to be accomplished are worth our study; these are: the relief of the pain, and the arrest of the carious process. The arrest of the pain is what the patient comes to you for, and prompt action is eminently desirable. I was much impressed with this in a case I saw a few weeks ago, in which an active business man, somewhat run down by overworking, suffered from toothache (I think due to caries) for several days before consulting his dentist, my friend Dr. Jarvie. The pain in the third division of the fifth nerve gradually subsided after treatment, but was followed by a well-marked neuralgia in the great occipital nerve of the same side. He again allowed some days to elapse before sending for me, and I found him suffering from a very intense crisis when I called. It was promptly relieved by the use of a remedy to which I invite your particular attention, namely, aconitia.
It has seemed to me for some time that this agent should form parts of the armamentarium of every dentist. From the fact that I have found it unused or unknown by some of your most progressive men, I shall not hesitate to say a few words about it to bring it before you.
Aconitia, or aconitine, is the active principle of the familiar drug aconite. Although discovered fifty years ago, it is only within the last ten or twelve years that it has been intelligently used. It is an extremely potent remedy, and must be used with great caution. In large doses it acts as a dangerous heart depressor, and paralyzer of motion and sensation. But in physiological doses it is without danger and is pre-eminently useful, because of a special action it has in relieving pain of the fifth nerve. In other neuralgias it is, for some unknown reason, far less potent. Our excellent Brooklyn pharmacist, Dr. Squibb, has put upon the market a most reliable preparation of this drug, an oleate, containing two per cent. of the crystallized salt. This seems to me a form which is peculiarly adapted to dental work. Ordinarily in prescribing this remedy internally I begin with 1
200 of a grain and repeat it every hour; often one or two doses will suffice to relieve the pain, and it is seldom that more than four are required.