Systemic effect of orthophosphates and polyphosphates on oral streptococci in young men 1

Abstract

Reduced susceptibility to dental caries by increasing phosphate levels in the diets has been reported in experimental animals. Phosphates may interfere directly with oral streptococci or exert their effect systemically, and previous studies indicate, that different phosphate compounds may exert varying degrees of inhibition. The systemic effects of ortho- and polyphosphates at two levels of calcium intake in ten young males were evaluated, in this study. Each subject consumed five diets: basal; low Ca, high orthophosphate or high hexametaphosphate; and high Ca, high orthophosphate or high hexametaphosphate. Mineral supplements were provided in capsule form. For each dietary period, oral streptococci in saliva and swabs of buccal and mandibular vestibule surfaces were enumerated and analyzed. Rate of sucrose metabolism and acid production in saliva samples was assessed by pH measurements, and phosphorus and calcium levels in saliva were assayed. Counts of colony, forming units on Mitis-Salivarius agar showed no statistically significant difference in any of the diets in either saliva, buccal, or vestibule surfaces. Acid was produced at a similar rate in all saliva samples, and mineral levels in the diets did not affect their respective levels in saliva 12–14 hours after intake. It is concluded that the cariostatic effect of phosphates in humans is not mediated systemically.