Effect of Dietary Phosphate Supplements on Dental Caries in the Rat

Abstract

The effect of various dietary phosphates on the occurrence of dental caries in the NMRI-D strain of rat was studied. It was found that the addition of either CaHPO4 or Na2HPO4 to a purified diet resulted in fewer carious teeth, fewer carious lesions and a tendency for the lesions to be less severe than in the unsupplemented control rats. The results with Na2HPO4 were confirmed, and it was found that (NH4)2HPO4 was also an effective cariostatic agent when added to the diet at a level equivalent to the Na salt. Na4P2O7 and Na5P3O10 were not effective. Titration curves of aqueous preparations of the various phosphates showed that Na4P2O7 had the highest pH in solution, and after reaching a pH of about 6.5 it titrated similarly to Na2HPO4 or (NH4)2 HPO4. If the buffering capacity of the various phosphate compounds is the only mechanism of caries reduction, Na4P2O7 would be expected to be effective; since it was not, some possible reasons were discussed.