Effect of Fluoride on Dentin Formation

It is known that fluoride helps to prevent tooth decay, however an excess of fluoride can cause enamel fluorosis. Although a great deal is known about enamel fluorosis, not much is known on the effects of excess fluoride on forming dentin, and its relationship to the tooth structure. To study the effects of fluoride on dentin, 4 week-old fluoride sensitive A/J mice were exposed to either 0 (control) or 50 ppm fluoride in drinking water for 3 weeks, after which they were sacrificed and serum fluoride levels were measured. The incisors were histologically analyzed for changes in dentin formation and relative expression of dentin matrix proteins and regulative proteins for its expression. These studies revealed that when exposed to excess fluoride, A/J mice exhibited a thicker pre-dentin layer. The relative amount of dentin sialoprotein was reduced in fluoride exposed incisors, possibly related to a direct effect of fluoride on Wnt signaling pathways. Taken together, these findings show that fluoride can alter dentin formation. These findings suggest that further human studies to further determine whether enamel fluorosis is predictive for altered dentin formation are needed. It is possible that if the quality of the dentin is affected by overexposure to fluoride, this may affect the incidence and rate of progression of dentin caries