FOSDICK, LEONARD S.: Dental School, Northwestern University, Chicago, Ill. (May 2, 1938).

 [For himself and co-workers in the Department of Chemistry: HAROLD L. HANSEN, GEORGE WESSINGER, ALBERT STARK, and ERNEST CAMPAIGNE.]

Caries is primarily a disease caused by degradation of carbohydrate ma­terial, by various enzymes, to hexosphosphoric, glycerophosphoric, phospho­glyceric, pyruvic, lactic, formic, acetic, butyric, and succinic acids—and perhaps others. There are other factors, such as proteolysis of the organic portion of tooth substance. The enzyme systems in the degradation of carbohydrate material may come from mouth bacteria, mouth fluids, or oral tissues.

No one type of organism has an enzyme system complete enough for rapid production of acid. A maximum rate of degradation occurs in the presence of a balanced enzyme system, with sufficient substrate. These two factors are influenced by three primary variables : kind and amount of bacteria, kind and amount of substrate, and enzyme system of mouth fluids and tissues. In turn these three variables are influenced by several others, such as diet ; nutrition; rate of flow, viscosity, and reaction, of saliva ; and occlusion and self-cleansing capacity of teeth. All of these factors influence rate of carbohydrate degradation in the mouth ; this rate, by saliva, is a function of susceptibility to caries, which, estimated upon this rate, correlates with clinical findings in 85 percent of 750 cases. Reactions in degradation of carbohydrate material in a salivary medium depend upon the enzyme systems of the bacteria, and the substances (including enzymes) in the saliva. Thus, presence of tricalciumphosphate or tooth substance changes normal produc­tion of alcohol by yeast enzymes to the formation of acids, which decalcify human enamel. A study of acid production in relation to caries should be conducted in saliva-tooth-substance media. To date, of the bacterial enzyme-systems studied, mixtures of yeast and B. acidophilus yielded the greatest amount of acid in the shortest time in a saliva-enamel medium. To evaluate these findings completely, it will be necessary to acquire further information on the enzyme systems of all types of bacteria that occur in the mouth, and on the enzymes of the mouth fluids and tissues. A complete study and quantitative evaluation of the several variables that may be contributing factors in caries will also be necessary.

References: J. Am. Den. Assoc., 1936, 1937 ; Northw. Univ. Den. Res. Grad. Study Quart., 1937.

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