Effect of long-term administration of fluoride on plasma fluoride and calcium in relation to forming enamel and dentin in rats

Abstract

Groups [3] of 1 mo. old rats were kept on water containing 0.2, 56.5 and 113 parts/106 F-, respectively, for a period of 2 mo. These groups were set up to study the relationship between long-term administration of high doses of waterborne F-, plasma values of F- and Ca and changes in forming dentin and enamel of the rat incisor. The microradiographic study revealed that increased levels of F- caused a delay in mineralization of the enamel. In the 113 parts/106 group the radiolucent areas in the enamel exhibited a distinct periodicity along the tooth, a phenomenon which cannot at present be explained. In the dentin the fluoride interfered with the process of mineralization giving rise to radiolucent and radiopaque banding in the experimental groups. With increasing levels of F- in the water supply a significant increase in plasma F- was recorded. The serum Ca values in both experimental groups were reduced to the same extent, which differed significantly from that of the control group. The F- doses which are needed to create fluorotic changes in rats may interfere with Ca metabolism and basic mineralization processes.