Abstract
A total of 588 weanling rats was used to determine the effect of different amounts of stannous fluoride and sodium fluoride on the incidence of experimental dental caries. Stannous fluoride furnishing 18 p.p.m. of fluorine in the drinking water decreased the incidence of caries approximately 75% in rats on a diet high in coarsely ground corn, whereas the decrease was about 50% when the supplement was sodium fluoride furnishing 21 p.p.m. of fluorine. Also, stannous fluoride furnishing 9 p.p.m. of fluorine in the drinking water, greatly lowered the incidence of caries in rats fed a high sucrose diet. In addition, different amounts of stannous fluoride and sodium fluoride were added to the high corn diet. In all cases the stannous fluoride was superior to the sodium fluoride in preventing caries. Stannous flouride furnishing 159 p.p.m. of fluorine and 500 p.p.m. of tin in the food was definitely injurious to the rats, as indicated by the marked impairment of growth and the abject appearance of the animals. However, this compound appeared to be no more toxic than sodium fluoride. With concentrations no higher than 26 p.p.m. of fluorine in the food or drinking water there was no evidence of toxicity. The reason for the superior effect of stannous fluoride remains to be determined. The tin moiety alone may have some beneficial effect, because large amounts of stannous chloride decreased the number of carious lesions, whether it was fed or given in the drinking water.