“Andry relates, however, that with the help of the microscope one may succeed in seeing certain worms that form beneath the deposit collected upon the teeth as the effect of want of cleanliness; these worms, he says, are exceedingly small and characterized by a small round head with a small black spot; the body is long and fine, pretty nearly like the worms seen in vinegar through the microscope. He adds that these worms destroy the teeth little by little, causing a bad odor, but not much pain. He believes it an error of the imagination to ascribe violent pains in the teeth to dental worms, and holds that these only produce a very slight, dull pain accompanied by itching.
“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.
It is undeniable that the ideas expressed by Fauchard on the pathogeny of caries, cannot hold good against criticism. Nevertheless, we owe a great deal to this author for having once for all put an end to the ridiculous theory of dental worms, and for having tried to find a reasonable explanation of the manner in which caries is produced.
The teeth, says Fauchard, have not all the same disposition toward this morbid process; indeed, notable differences are to be observed in this respect. The molars are, in fact, more apt to become decayed than the incisors or the canines; and the upper incisors and canines are more subject to this disease than the inferior ones, because, by reason of their position, they are more frequently uncovered and more exposed to heat and cold, whether in eating and drinking or whether in the mere aspiration or expiration of the air. It is to be observed, besides, that when the eruption of the last molars is considerably delayed they easily decay.[418]
Having very frequently observed the symmetrical decay of corresponding teeth on both sides of the same jaw, Fauchard considers that these cases are not simply accidental, but rather holds that the fact depends on a special cause, which, however, is not easy to determine. He offers, at any rate, a sufficiently good explanation when he says that as certain morbid causes (bad humors, etc.) must affect both sides of the mouth identically, it is but natural that the effects of such causes should be altogether analogous on the right and on the left, and manifest themselves symmetrically on teeth having the same configuration, the same structure, and the same consistence.
Before speaking of the treatment of caries,[419] Fauchard alludes to the fallaciousness of the many remedies against toothache which were largely sold at his time by charlatans and impostors of every kind.
“Some pretend to cure toothache with an elixir or some special essence; others with plasters; others by means of prayers and signing with the cross; others with specifics for killing the worms that are supposed to gnaw the tooth and so cause pain; others pretend to be so clever that they can cure the most inveterate toothache by merely touching the tooth with a finger dipped into or washed with some rare and mysterious liquid; others finally promise to cure every kind of toothache by scarifying the ears with the lancet or cauterizing them with a red-hot iron.”