The effect of sodium fluoride on the calcification of the enamel and dentin of the rat incisor.

According to SCHOUR and SMITH (1934), in ground sections viewed microscopically with transmitted light, enamel and dentin showed light (disturbed) and dark (recovery) incremental layers for each injection of sodium fluoride. IRVING (1943) injected fluoride in different doses in an attempt to estimate its effect on the basis of the amount per kilogram of body weight of the animal. Both hypocalcification and hypercalcification of the dentin occurred. When the phosphorus or calcium in the diet was reduced, only hypercalcification of the dentin occurred following fluoride injection. YAEGER and EISENMAN (1963) have reported that the injection of fluoride induced both hypomineralized and hypermineralized increments in forming dentin. It was observed by ALLAN (1963) that the enamel of young dogs injected with smaller doses of fluoride showed hypercalcified lines only. WEBER and YAEGER (1964), on the other hand, induced a pair of lines in the enamel when they gave parenteral doses of fluoride to rats. The pair of lines showed up in the historadiographs as hypomineralized and hypermineralized lines. The purpose of this study was an investigation of the response of the enamel and dentin in the incisor teeth of rats injected with sodium fluoride.