SECTION VII.

PHYSIOLOGY AND ETIOLOGY.

REPORT BY W. C. BARRETT, CHAIRMAN.

[Before making his report, Dr. Barrett passed around several sealed tubes containing pure cultures of several of the forms of micro-organisms found in the mouth, which he stated were prepared by Dr. Miller, of Berlin.]

PHY

Physiology.

HYSIOLOGY may be defined, the study of function. Everything, therefore, that has special reference to the nutrition of the body, to secretion and to excretion, may be properly considered under this head.

Digestion is a function the object of which is the preparation of alimentary substances for assimilation, and the separation and expulsion of the excrementitious portion as fæces; assimilation is the function by which living bodies appropriate and transform into their own substance the products of digestion. Both together constitute the function of nutrition.

That the condition of the organs which it is our special province to care for is very largely dependent upon their nutrition, no thinking man will deny. In many instances a perversion of nutrient currents, a lack of tone in the assimilative or digestive machinery of the system, is primarily manifested in the teeth. A perfect apparatus must perform perfect work. Given, then, an individual with a healthy, normal nutrition, the teeth should, in the absence of malformations that may be denominated accidental and extraneous to the present consideration, be anatomically and histologically perfect. Subsequent lesions are, of course, pathological, either externally or internally, and their consideration is not pertinent to the present inquiry. Given, again, an individual with structurally imperfect

teeth, and it follows, if our reasoning be correct, that the fault is nutritive.

What, then, is the exact source of the lesion? Is it in the digestive or the assimilative functions? Is it pre-natal, and therefore maternal, or is it personal to the diseased organism? Is it general or local? Is it due to improper or imperfect alimentation, or is it strictly and entirely functional? These are questions that may well make us pause in the generalizations with which we are apt to stifle the inquiries that naturally arise within us.

It has been urged that our structurally imperfect dental organs are due to unnatural habits of life; to improper diet; to the vicious preparation of articles of food; to the removal of necessary ingredients from that which nature has provided as pabulum; in fine, to an artificial and abnormal manner of living. In a paper previously published I have considered these points. You will allow me to repeat some of the conclusions to which I there arrived.

If imperfect teeth be due to any of these things, it will only be necessary for us to go back to the natives who were free from all the so-called vices of our modern civilization, to find a different state of affairs. During the past year I have received the testimony of many observers who were stimulated to inquiry by the published accounts of the condition of the teeth of certain pre-historic races. I have received letters from many professional men who have made examinations, more or less critical and exhaustive, of collections of skulls in all parts of the world, and of very many of the earlier races of people, who existed under the most diverse conditions, in all extremes of climate, whose habits of life were the most widely varied, and whose food ranged from the almost exclusively fruit diets of the tropics to the wholly animal alimentation of the frozen regions of the far north. With a single exception, all these observers bear witness to the fact of the existence of nearly all of the dental lesions of the present day; and the general verdict has been that, from the carliest times of which there remain dental traces down to the present, there have been little other than local changes in the condition of the dental organs. Our honored President exhumed about a dozen skulls of the early Egyptians, and the impression upon his mind was that they were comparatively free from the evidences of oral diseases, but, as I understand, he made no records at the time, and his evidence is but the dim recollection of hurried observations made some years since. In any case, the number of skulls examined was not sufficient to indicate anything more than a possibly acci

dental deviation from the general condition. Dr. J. J. R. Patrick, of Belleville, Ill., has exhumed and examined the skulls of thousands of American aborigines,-races that existed long previous to the advent of the American Indian,-and his evidence is positive upon this point.

These records are fatal to the theory that dental lesions and imperfect structural development are modern, and due to our present artificial habits of living.

It is true that wild animals, in the absence of interfering accidents, have perfect dentitions; but it is also true that in them traumatic lesions heal without suppurating inflammation, indicating more perfect function. (In an examination made this summer of the skeleton of the Elephas giganteus-the Mastodon exhumed at Cohoes, and now in the State geological collection at Albany-I discovered an abnormality in the absence of one of the molar teeth; but any one who is acquainted with the process of the eruption and shedding of the teeth of all of the genus Elephas, will readily understand that this may easily have been accidental).

It seems demonstrated that general structural imperfections of the teeth of man reach far back, and antedate the historical era. As the teeth of animals remain structurally perfect under all vicissi tudes of alimentation,-whether rioting in plenty or barely existing in a state of semi-starvation, whether feeding upon the crude products of nature or living upon food prepared for them in a state of captivity, and as the teeth of man are in general structurally imperfect under all circumstances of diet and habits of life, it cannot be that mere dietetic influences exercise any very important part in the development of the teeth, and therefore the prescribing of artificial foods, of the phosphates, etc., for the purpose of supplying lacking elements, is founded on a mistaken theory. If they act at all, it must be remedially.

A careful analysis of some of the foods supposed to be lacking in the phosphate elements that enter into the bones and teeth, finds an amount largely in excess of the needs of the system. Even supposing a pregnant woman to live solely upon the finest wheat flour, the amount that she would consume contains a much greater quantity than would suffice for her own wants and those of the fetus that she carries. It is a fact that pregnant women and rachitic children excrete the mineral elements largely, showing that under all circumstances it exists in excess in the food.

Considering all these facts, we must seek in functional disturb

ances, in impaired digestion and assimilation, the cause for anatomical and histological imperfections in the teeth. But the record of these abnormalities (if they have not already become the normal condition) extends so far back that it demonstrates these functional divergences as inherent to the present condition of the human race. Whether in the long course of development of man in his present state from some lower order, or from some remote intellectual condition, the nervous organization-the brain, the intelligence-has been cultivated at the expense of the mere animal functions, it might be profitable for ethnologists to inquire. That the causes of the lack of perfect development in any part of the human system are in some way connected with non-assimilation, many considerations lead us to believe. That the habit of looking solely to the diet to find reasons for existing abnormalities is a search in the wrong direction, most thinking men will admit. It is time for dentists to take a broader view, and by a more careful study of function, by deeper physiological research, by the abandonment of specific treatment and a careful examination of all the factors that enter into the problem of existence, to endeavor to become physicians indeed, in the very broadest sense of the term.

THE ETIOLOGY OF DENTAL CARIES.

It is indisputable that within the last five years more has been learned of the probable character of dental caries than during the whole previous history of the profession. The late discoveries of Koch, Pasteur, DuBois-Raymond, and others, in the pathology of zymotic diseases, have paved the way for investigations that have revealed the nature of many oral diseases.

Sir William Jenner was far in advance of his age when he discovered that inoculation with the vaccine matter from animals suffering with cow-pox was a protection from that dread scourge, small-pox. He had noticed the relation between the two diseases when but a student, because of the popular belief that the two were antagonistic. At length, after long study, he inoculated a boy about eight years old, on the 14th of May, 1796, with cow-pox matter, and subsequently with variolous matter, and, as he had predicted, small-pox did not ensue. But he was far from comprehending the true principles of this protection, and, until a recent period, vaccination for small-pox was but an empirical method, accidentally discovered. It was left for modern pathologists to demonstrate that all the so-called zymotic diseases, together with many others not

previously suspected as such, were due to certain microscopic organisms that multiplied with astonishing rapidity in the human system; that each one of these maladies had its specific organism, but that they were antagonistic to each other, and that when certain ones had been allowed to run their course they exhausted the ability of the body to nourish certain others. Physicians had always been aware that a patient who had once had small-pox was not liable to a second attack, except under circumstances and conditions that were very unusual. The studies and observations of Koch gave us a clearer insight into the character of those organisms, for he isolated some of them, and learned their life-history. Finally, Pasteur crowned the work with his immortal discoveries, and to-day we know that if a person be guarded against the intrusion of these microbes, the contagious diseases need no longer be feared. We have learned that the final dissolution of all nitrogenous substances is invariably brought about by the influence of micro-organisms, and Tyndall demonstrated that if they be excluded putrefaction and fermentation are effectually prevented.

Few, however, even in view of these discoveries, would have anticipated that any of these organisms might prove to exert an influence in the production of dental diseases. The theories concerning dental caries that had been entertained held that the disease was but a chemical solution of matter that must be considered inorganic. The fact that it was living, vital tissue was not considered, and caries was looked upon as a simple change of affinities, such as occurs in the chemist's retort.

In 1868 Drs. Leber and Rottenstein published their work on "Dental Caries and its causes," and in 1873 it was translated into English by Dr. T. H. Chandler, of Boston. In this they advanced the theory that the disease was mainly due to the influence of certain fungi of the mouth, the chief of which was Leptothrix buccalis. Long previously it had been discovered that vegetable organisms existed in the oral cavity, but comparatively little weight had been given to their presence, which was usually supposed to be accidental. Ficinus had averred that dental caries was sometimes due to infusorial animalcula that produced a putrefaction of toothsubstance; to these he gave the name of Denticolæ. Klencke described a soft caries caused by putrefaction, as he called it (at present we know that caries is not produced by putrefactive, but by fermentative, organisms), and another due to a parasite that he called Protococcus dentalis. But these observers made little impression.