SUSCEPTIBILITY TO DENTAL CARIES IN THE RAT

VIII. Further Studies of the Influence of Vitamin D and of Fats and Fatty Oils

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

One series of 90 rats were given a basal coarse rice-dextrin-spinach diet alone or supplemented in separate groups of 12 or 13 animals with viosterol in corn oil, or with corn oil or paraffin oil alone. One group was given a viosterol-corn oil dilution by pipette, 2 drops per rat per week, in amount equivalent in vitamin D to about 196 U.S.P. units per week, and in fat to about 0.15 per cent of the diet. Another group received an approximately equal amount of viosterol and corn oil incorporated with the diet. Two other groups received respectively about 70 and 175 units of vitamin D as viosterol incorporated in the diet with corn oil equivalent to 5 per cent of the diet. In the oil-control groups, the oils were fed as 5 per cent of the diet.

Another series of 152 rats, in 12 groups of 10 to 14, were given (a) a basal coarse corn-saccharose-spinach diet alone and supplemented with 0.5, 2 and 5 per cent of corn oil; (b) a basal coarse rice-saccharose-spinach diet alone and supplemented with 0.5, 2 and 5 per cent of corn oil; and (c) the same basal rice diet supplemented with 5 per cent of olive oil, cottonseed oil, hydrogenated cottonseed oil and lard.

All animals were placed on the diets at 22 days of age and kept on the diets for varying periods up to 162 days in the first series and 100 d s in the second. The incidence of fissure caries and other dental lesions and the degree of calcification of teeth and alveolar bone were determined by microscopic examination of sections of the jaws. Blood calcium and phosphorus were determined in representative animals of the first series. The results are as follows:

Vitamin D at the levels used, independently of the manner of feeding or the level of accompanying oil, induced a characteristic statistically valid decrease in the level of fissure caries as compared with the control group.

Increasing percentages of corn oil with both corn and rice diets gave decreasing levels of fissure caries, except that with the rice diet 2 per cent of corn oil yielded, as in previous experiments, the full "adequate diet effect" and 5 per cent was not more effective. Corn oil at each level was more effective in reducing the level of caries with the rice than with the corn diets. Since the amount of oil bound in the grain is considerably higher in corn than in rice, the findings suggest that free rather than bound oil is the effective factor against caries, hence that the effect is exerted locally in the mouth rather than systemically or via nutritional processes. The possible mechanisms of such effect are discussed.

The fats used other than corn oil were at least as effective against caries as corn oil. Paraffin oil was apparently less effective than the fats and fatty oils.

The relationship of the findings to those of other workers on the influence of vitamin D and of fat on dental caries in children is discussed.

Details relating to the occurrence of cusp fracture ("macroscopic") dental lesions are also given.