“I have done everything possible,” continues Fauchard, “to convince myself with my own eyes of the existence of these worms. I have made use of the excellent microscopes of Manteville, sworn surgeon of Paris, and have made a great number of experiments with them both on caries in teeth newly extracted as well as on tartar of different consistency accumulated on the same, but have never succeeded in discovering any worms. I am also still less disposed to believe in the existence of these animals, because Hémard declares that he has never been able to find any worms in carious cavities. I am thoroughly convinced of Andry’s sincerity; neither do I doubt the truth of the facts he relates; but it is easy to perceive from his own words how little the pretended healers of teeth and their specifics for killing worms are to be held in account; from the moment that, according to this writer, the pains for which one is most obliged to have recourse to remedies are almost always those not proceeding from the cause in question.” In short, Fauchard does not believe at all that dental caries is occasioned by worms; and only from respect for the authority of Andry and other writers does he admit the accidental existence of these little animals in the carious cavities or upon the teeth, refusing, however, to attribute any importance to the same as regards the etiology of caries. This disease, says Fauchard,[417] is produced by a humor that insinuates itself into the midst of the osseous fibers of the teeth, and displacing the particles which compose these fibers, gives rise to their destruction. The causes from which these disorders derive may be external or internal. The external causes are blows, violent efforts made by the teeth; the improper use of the file, the application of acids or of other substances that injure the enamel, alteration of the saliva, impressions of heat or cold, and also certain kinds of nourishment. Blows or violent efforts may produce caries, according to the writer, by occasioning the effusion of the liquid contained in the vessels. The author gives analogous explanations for the other external causes. As to the internal causes, they consist, he says, in alteration of the blood and of the humors. The teeth, says Fauchard, are more subject to caries than all the rest of the bones in the human body, because, their tissues being denser, the vessels are on this account closer together and more easily liable to be obstructed, choked up, and broken. Besides, the position of the teeth exposes them more than the other bones to the immediate action of external causes capable of producing the disorders alluded to; and finally, what demonstrates the dental caries to be produced, for the most part, by external causes, is that false teeth, either human or formed from those of animals, sometimes become carious just in the same way as the natural ones; which evidently happens by the sole action of external causes.