SUSCEPTIBILITY TO DENTAL CARIES IN THE RAT

VII. INFLUENCE OF MINERAL SALTS, PROTEIN AND SUGAR, AND RELATIONSHIP OF CALCIFICATION OF TEETH AND BONE

¹ Departments of Bacteriology and of Biological Chemistry, College of Physicians and Surgeons, and School of Dental and Oral Surgery, Columbia University, New York City

In one experiment 65 rats 22 days of age were given diets adequate but for vitamin D and without added fat for periods ranging from 50 to 167 days. Two diets were used, identical except that one contained coarsely ground brown rice, the other coarsely ground yellow corn, as the primary caries-producing ingredients. Despite the absence of vitamin D or added fat the resulting caries levels in both groups were low, falling within the range we have found to be characterstic of adequate diets or of diets containing adequate vitamin D or corn oil.

The histological picture of calcification of teeth and alveolar bone varied among individual animals in these groups from normal to defective, but such variation could not be correlated with the respective degrees of dental caries. In another experimental series 113 rats 22 days of age were distributed among groups that received a basal deficient caries-producing diet containing either coarsely ground brown rice or coarsely ground yellow corn, with the addition, in individual groups, of saccharose at several levels, and of 1 per cent of calcium lactate, alone or with 7 per cent of egg albumin. Animals that survived were killed after 100 days of feeding, but many of the animals died from the 33rd day on.

The increasing levels of saccharose tended to increase the incidence of caries on both the rice and the corn diets, but inconsistently and to a degree that is not statistically significant. The calcium lactate addition, although it effected a slight improvement in calcification of bone and teeth, did not reduce the incidence of caries with either the rice or the corn diet. The further addition of protein, on the other hand, brought about a reduced incidence of caries in both rice and corn groups, more effectively in the corn group, despite the fact that this diet yielded a much higher mortality than the corresponding rice diet. Among the other groups in this series there was likewise no apparent relationship between the percentage of animals that died before the end of the 100 day experimental period and the incidence of dental caries.