BRODERICK, F. W.: Bournemouth, England (June 29, 1938).

There is no special or specific cause of dental lesions. Fundamentally the causes of all diseases are the same, although there may be many manifesta­tions, dependent upon differences in structure and environment of the various organs and tissues. The matter becomes primarily one of constitutional vege­tative imbalance upon which environmental circumstances act. This concep­tion explains much that is otherwise inexplicable in medicine : the constitutional element in disease ; the antagonisms of disease, so well illustrated in caries and pyorrhea; the association of dental and more general lesions along the lines of a common origin rather than of cause and effect through sepsis.

The author believes (a) that caries and pyorrhea are etiologically and clinically opposite and antagonistic to one another, the consequences of devia­tions of physiology in opposite directions, and (b) that gingivitis is not causally related to pyorrhea and can be, and frequently is, associated with caries. Disturbance in the acid/base balance of blood and body tissues ac­counts for both caries and pyorrhea—acidosis being associated with the former, alkalosis with the latter—but this conception does not clarify the milder condi­tions of imbalance. So long as our ideas are bounded by a chemical conception, such as is entailed by acid/base balance, gingivitis cannot be placed in its proper relation to these two conditions, which is absolutely necessary to obtain a clear visualisation of the etiology of either. The modern conception of the vegeta­tive system removes this disability. The physiological control of all in­voluntary function is now believed to be attained through the innervation of the vegetative nervous system and a number of associated factors, including the ratios between ions of potassium and sodium and of calcium and mag­nesium; the hormones of thyroid and adrenal glands working in conjunction with the sympathetic side of the vegetative nervous system, and insulin with that of the parasympathetic side; and the state of the colloidal electrolytes. With an imbalance to the sympathetic side of the vegetative system there is, in addition to sympathetic nervous overaction and excess of thyro-adrenal stimulation, an excess of calcium over potassium in the body cells, a tendency to acidosis of the body fluids, and dehydration of the plasma colloids. The reverse occurs with parasympathetic predominance. By distinguishing the etiological factors of gingivitis from those of caries at one extreme, and of pyorrhea at the other, all our difficulties disappear. We see that the etiological factors in caries and pyorrhea are opposite and antago­nistic to one another, and we have a yard-stick to measure any suggested causes of either. The etiological problem of either condition is one, not two. It becomes clear how acidosis, through ensuing alteration in the reaction of saliva, slowly decalcifies enamel in those positions in which food plaques tend to be present ; and why, when the mean salivary reaction is well over to the alkaline side—from which pH-point many and varied factors, life being a dynamic process, cause constant departure—even food fermentation cannot bring about such decalcification. The hypercalcification of enamel, with caries immunity, is understandable by reversing the factors on which caries depends, substituting a tendency to alkalosis for that of acidosis. When we consider the question of pyorrhea, we have to include not the production of only one sign, enamel decalcification, but a number : hypercalcification of enamel, giving immunity from caries; gingivitis, either simple or suppurative; deposition of a particular kind of calculus, in a particular position in relation to tooth and supporting tissues ; and alveolar destruction. Here we find that a consideration of only a disturbance of acid/base balance in the direction of alkalosis does not give all the information we need. When, however, we take into considera­tion the other factors in the build of the vegetative system, all these are readily explainable.

To understand the foregoing theories, certain fundamental misconceptions must be appreciated. Disease is a dynamic process, not a static thing. Although with the present conceptions of medical science, disease cannot be diagnosed until it has altered function or damaged tissue, this does not necessitate the conclusion that disease occurs suddenly, or commences when function is altered or tissue damaged. It is but common sense to conclude that a milder disturbance pre-dated these changes, which must have been mild deviations in normal physiological processes. These deviations are simply physiological ones carried to extremes, and persisting over prolonged periods of time, as are deviations related to the waking and sleeping hours, normal digestive processes, etc. What are ordinarily called diseases are not in reality separate and distinct entities, but rather consequences of certain bio­chemico-physical changes which are normal processes carried to extremes, and constitute the disease. What have been called diseases are in fact only symptoms of disease, or else end-points brought about by organic changes in organs and tissues dependent upon continuation over a long period of time. Thus caries and pyorrhea are not essentially diseases but only symptoms of disease states.

Just as the modern conceptions of chemico-physics—built upon the work of Rutherford on the structure of the atom—has led to the science of physical chemis­try, which has revolutionized both chemistry and physics, and removed many mys‑teries from each, so colloid chemistry helps in our search for etiological factors. Whilst we were bounded by a chemical conception, the colloids evaded us because it was impossible to conceive a unit that was partly acid and partly alkaline at the same time. Only the more extreme cases were understandable. When we begin to think in terms of physics, it is possible to conceive—in fact it is almost universal in vegetative imbalances to find—persons having both hydrated and dehydrated colloids in the blood plasma at the same time, of course in differing proportions. With this conception it is possible to place cases showing gingivitis in a distinct position differ­ing from those showing either caries or pyorrhea. Gingivitis cases come where the proportion of dehydrated to hydrated colloidal particles approaches or departs from the ratio 1 : 1—a position where all inflammatory phenomena make their appearance. Caries appears where the proportion of colloidal dehydration greatly exceeds that of hydration ; pyorrhea, where hydration is in excess. Thus this centre group over­laps either of the extremes, giving a tendency to gingivitis associated with caries or pyorrhea, and the presence of either without gingivitis. It is necessary, however, to be quite clear upon one point : whereas acids and alkalies neutralise one another— so that when these are present in equal reactive amounts there is normality— hydrated and dehydrated particles do not ; in health—normality—there should be neither one nor the other. The presence of either, or both, shows a deviation from physiological vegetative balance.

The gingivitis so often associated with pyorrhea is explainable along the lines of a hydration-dehydration ratio near to 1: 1, getting less as this difference in­creases in the direction of hydration excess, until it reaches a position where the dehydration element is greatly diminished and alveolar atrophy presents. In this case factors responsible for alveolar destruction are more in evidence, accounting for greater destruction of bone. Infection of gingival margins is dependent upon alteration of the soil in which microorganisms live, permitting change from harm­less saprophyte to hurtful parasite—not a new infection. This result is entirely dependent upon alterations in vegetative status of the individual ; calculus deposition rather than tartar sedimentation depends entirely upon the state of body colloids and the reaction of body fluids, and inevitably conies about when the colloids tend toward hydration and the reaction tends toward alkalinity. Alveolar destruction is dependent upon change in vegetative balance in the direction of parasympathetic dominance, associated with calcium deficiency and dilatation of capillaries and small blood vessels.

Reference: The principles of dental medicine ; 3d ed., 1938 (C. V. Mosby Co., St. Louis, Mo.).

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