THE EFFECT OF PARTLY SYNTHETIC DIETS ON THE DENTAL CARIES INCIDENCE IN SYRIAN HAMSTERS

¹ Walter G. Zoller Memorial Dental Clinic and the Department of Bacteriology and Parasitology, University of Chicago, Chicago, Ill.

Based on the assumption that certain oral bacterial are important in the development of dental caries, this investigation concerned itself with the environment of the oral cavity in the Syrian hamster. The factors considered were: (A) the nutritional substrate provided by the ingested food, (B) the bacterial flora subsisting on this substrate, and (C) the molar teeth subjected to carious destruction presumably by the action of the bacteria. Partly synthetic experimental diets containing 11 vitamins in measured amounts, with 1 or 2 of these vitamins being omitted from each test diet, were fed to 682 hamsters distributed into 18 different dietary groups for a 100-day period. During this time, the animals were provided with adequate amounts of the missing vitamins semiweekly by intraperitoneal injection for their own nutrition. As a plausible measure of the degree to which certain oral bacteria were retarded or accelerated in their growth and metabolic activities, the extent of the various lesions in the hamsters' molar teeth were evaluated.

The trends observed in this study were the following:

1. When vitamin K was absent in the diet, hamsters showed the greatest amount of dental caries.

2. The animals on a diet deficient in choline chloride developed about twice as much caries as animals in the control groups.

3. With the omission of nicotinic acid, the amount of caries was reduced to about one-half that of the control animals.

4. Animals receiving neither nicotinic acid nor inositol showed a higher degree of dental caries than the control animals.

5. Absence of vitamin E did not seem to prevent lesions from occurring but apparently retarded their progress.

6. Substitution of dextrin for sucrose caused a 50 per cent decrease in molar destruction by dental caries.