LILLY, C. A.: University of Michigan Hospital, Ann Arbor, Mich. (Oct. 4, 1938).

Caries, in rats, is not definitely related to deficiency of any known food factor. Diets containing 66 percent of corn starch, sucrose, glucose, lactose, or maltose, did not induce caries in rats in six and one-half months. Diets containing 53 percent of corn starch or sucrose, fed for one year to rats that received tri-weekly oral inoculations of pure cultures of B. acidophilus, did not produce caries.

Caries did not occur in rats on diets deficient in vitamins A and B, although many died showing symptoms of deficiency of these vitamins. Rats kept in a dark room after weaning, on Steenbock-Black rachitogenic diet No. 2965 for six to ten months—or until they died—did not develop caries, if the corn in this diet was ground sufficiently fine to pass through a 60mesh sieve. These animals de­veloped roentgenologic evidences of florid rickets, dental malocclusions, and bone defects and deformities, but not of caries. Rats that were developed on diets containing one-fourth the amount of minerals, plus one-half the amount of protein, of Mendel’s normal-rat diet, had only one-third the reproductive properties and one-half the weight of normally fed rats, but did not develop caries. Diets inwhich calcium and phosphorus contents ranged from 25 percent to the full values of Menders normal-rat ration, produced bones that yielded ash definitely com­parable, in calcium and phosphorus values, to those of the diets; but the ash of the molar teeth was never less than that for rats on a normal diet. In rats, molar teeth seem to have a ” preference,” over bone, for the available calcium and phos­phorus of the diet. The Hoppert-Webber-Canniff coarse cornmeal diet produced caries in 60 percent of the tested rats ; but when the corn meal in the diet had been ground sufficiently fine to pass through a standard 60-mesh sieve, no caries oc­curred even in the second generation. Boiling (softening) the corn meal, before it was fed, also prevented occurrence of caries. Addition of purified sea-sand to the finely ground corn-meal in the diet (10 percent by weight) resulted in caries in 25 percent of the rats thus fed. Addition of vitamin D (viosterol) to coarse corn-meal diet did not affect the incidence of caries produced by that diet. Slow- starvation diets, high- and lowfat diets, and diets containing large amounts of cellulose, such as wheat- and corn-bran, produced no caries. [Study in progress.]

Reference: None submitted.

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