Note (32) — CANTO THIRD.

Caries is the most frequent disease of the teeth. The general seat of it is, on the sides of the front teeth and in the centre and sides of the back ones. Its progress through all its different stages is easily marked. First of all, a small dark spot appears on the enamel, through which the disease quickly passes into the internal structure of the bone. When this has taken place, the least pressure from chewing any hard substance is liable to break away portions of the enamel, and thus the internal part becomes subject to every injury which can arise from extraneous matter lodging therein. The molares are more subject to this disease than the front teeth; first, because their indented surfaces more readily retain any extraneous matter; and secondly, because they are less in view, and consequently less attended to.

In the enamel of the most apparently perfect teeth, small cracks may, with a magnifying power, easily be discovered. These, although unnoticed by the individual, are sufficient to admit disordered fluids, and to account for many forms of decay. This may likewise account for decay taking place in the broad surfaces of the molares, where the points of contraction always produce a depression, and thus afford a convenient lodgment for acrid saliva and other decomposing agents.

From my own observations I am induced to believe, that caries is universally caused by the action of external agents; and therefore cleanliness, and a due regard to the general health, after the proper offices of the dentist are performed, is the only guard against it. But some teeth, from their being of less dense structure, are less capable of resisting the action of decomposing matter, and consequently will require greater attention to ward off disease.

Mr. Brewster, of Charleston, whose experience, from having been fifteen years in extensive practice, has given him ample opportunities of judging, has, in a manuscript with which he politely furnished me, enumerated the following as the principal causes of decay. Constitutional softness of the teeth; The use of medicines during dentition or in after life; The too free use of acids, which, uniting with the lime in the enamel, destroys its strength; A too slow growth of the teeth between the time of protruding their points through the gum, and the full development of their crowns. It will often happen that the projecting points of the grinding teeth pass through the gum, and there for a long time remain with a portion of the surface, comprehending the indentations of the grinding surface, partially covered with the gum. As there is no union between the enamel and the gum, fine and soft particles of food insinuate themselves between the gum and the tooth. This matter decays, and the acid generated thereby acts perniciously on the enamel, and lays the foundation for subsequent decay of the tooth. The remedy is simple, and, in most cases, effectual. It consists in removing the gum from the top of the tooth, which is performed by a skilful operation, with little or no pain to the patient. This prolific source of decay I am not aware has ever been noticed by any writer on the teeth. Another prolific source of decay is the permitting a new tooth to come in contact with the decaying part of an old one. The remedy consists in removing a portion or the whole of the old tooth.

The too free use of mercury; The accumulation of tartar; Neglect of cleanliness by suffering the particles of food to remain between the teeth after meals; Irregular living, or any other cause which occasions a disordered stomach; Extremes of heat and cold; All Acids, whether in fruits, powders, or lotions; Metalic toothpicks; Injudicious dental operations; Most of the nostrums administered for tooth ache.

“I propose,” says Mr. Bell, “to substitute for the word caries, the term gangrene of the teeth, which expresses the real nature of the disease. It may be defined—mortification of any part of a tooth, producing gradual decomposition of its substance. It usually attacks the crown of the tooth; sometimes, though rarely, the neck; but I believe it scarcely ever makes its first appearance on the root. It invariably shows itself on the external surface of the bone, immediately underneath the enamel, and its existence is, in many cases, first indicated by an opaque spot on that substance, occasioned by partial breaking down of its crystalline structure; in others, its presence is shown by the discolored bone being seen through the semi-transparency of the enamel.” (Bell on the Human Teeth, p. 118.)

I have made the foregoing quotation from the work of Mr. Thomas Bell, with whom I once conversed personally on the doctrine contained therein, for the purpose of expressing my entire dissent from the opinion held by most of the writers on this subject, in relation both to the local origin, and the immediate cause of caries, or dental gangrene. Some of these writers divide the disease into two kinds, which they distinguish by the names external and internal caries; while others inculcate the doctrine so hostile to all my experience and observation, that caries commences, as Mr. Bell says in the passage quoted, on the surface of the bone, under the enamel, and that the disease becomes visible through the semi-transparency of the enamel, which itself is destroyed by being broken away by mechanical violence. Now I must aver, that after a constant and extensively diversified practice of nineteen years, both in Europe and America, I have never known a solitary instance of this disorder which was not evidently occasioned from external causes on the surface of the tooth, penetrating first through the enamel, if on the body of the tooth, and then assailing the bony structure.

There are teeth that are faulty, both in their enamel and organization; owing, probably, to constitutional or hereditary peculiarities which have not, as I am aware, ever been satisfactorily explained by any author.

As to the cause of caries, I published my opinion many years ago, first in London, and afterwards in this city, and have seen no cause to espouse a contrary opinion. I consider the immediate and exciting cause of dental decay to be always external to the tooth itself, and to consist of certain corrosive menstrua, to which these organs are exposed from bodily disease, improper aliments, powerful medicines and the thousand other sources of acrid filth and destructive poisons that become concentrated in the mouth and deposited upon the teeth. These procuring causes of caries may indeed derive their origin from constitutional diseases acting upon the system at various periods of life, but whatever internal defect of structure a tooth may derive from original organization, how much soever it may be predisposed to take a diseased action under favorable conditions, still, the tooth never decays till externally affected by putrescent, or corrosive, or disorganizing matter, which breaks up its structure.

That such has been my uniform opinion, will be seen from the following extract from the work on the stomach and digestive organs, published by Dr. Thomas Hare, Fellow of the Royal College of Surgeons in London, in 1821.

“The theories concerning the cause of decay in the teeth which seem to have met most attention, are those referring it to an undue degree of compression exerted by the irlateral surfaces on each other, and to a putrefactive fermentation of extraneous matter lodging in the interstices. The former has been ably set forth by Mr. Bell, of St. Thomas’s Hospital, in the Medico-chirurgical Transactions; the latter was published about two years ago, by Mr. Parmly.” (page 269.)