Effect of suboptimal zinc nutrition during gestation and lactation on rat molar tooth composition and dental caries.

The main objective of this study was to determine the relationship between zinc content of teeth and susceptibility to dental caries. Pregnant albino rats were fed a purified diet containing 8, 15 or 30 ppm zinc throughout gestation and lactation. Food intake of all rats was restricted to that consumed by the lowest zinc group. At day 20 of lactation, pups were weaned to a high sucrose, caries-promoting diet and orally innoculated with streptococcus mutans. Dams consuming the lowest zinc-containing diet exhibited a mild zinc deficiency as evidenced by reductions in gestational weight gain and zinc content of milk, serum and tibia when compared to other groups. All offspring survived. Pups originating from the lowest zinc group had significantly less zinc in molar enamel and dentin fractions compared to other groups at the end of a 30-day caries test period, but tibia zinc was essentially equal. This apparent pre-eruptive reduction in zinc content of enamel and dentin of offspring was associated with significantly greater dental caries score on the buccal surface. This suggests that moderate dietary zinc deficiency is sufficient to reduce the pre-eruptive zinc content of both enamel and dentin and to increase dental caries.