RESUMO
<p><b>OBJECTIVE</b>To investigate the effect of different concentrations of fluoride on the expression of transforming growth factor-beta1 (TGF-beta1), and explore the mechanism of dental fluorosis.</p><p><b>METHODS</b>40 Wistar rats were randomly divided into three groups, and supplied with low dose F(-)(60 mgxL(-1), 13 rats), high dose F(-)(120 mgxL(-1), 13 rats) and distilled water(control group, 14 rats) respectively. After 10 weeks, hematoxylin-eosin (HE) and immunohistochemistry staining were used to observe the changes of the ameloblasts and the expression of TGF-beta1 in rat incisors.</p><p><b>RESULTS</b>The fluoride groups showed typical symptoms of dental fluorosis. The surfaces of the rat teeth fed with fluoride appeared chalky color and cross striation on the enamel surface. The HE staining showed that the morphous of ameloblast were disarranged and cellular derangement, even appeared vacuolar change. TGF-beta1 were expressed both in ameloblast of the secretory and maturation stage, and also in stellate reticulum and stratum intermedium. The expression of TGF-beta1 in rat's ameloblasts in experiment group was significantly lower than that in the control group (P<0.01), yet low dose group and high dose group still had no significant difference (P>0.05).</p><p><b>CONCLUSION</b>By inhibiting the expression of TGF-beta1 in ameloblast, fluoride interferes the normal signal transduction between epithelial and mesenchymal, and affect the differentiation and development of enamel, so leading to the occurrence of dental fluorosis.</p>