Abstract:

Dept. of Oral Medicine，Hospital of Stomatology, Tongji University, Shanghai 200072, China）[Abstract]  Objective  To investigate the effects of overdosed fluoride on the expression of MMP-20 and TIMP-2 in rat incisor. Methods  20 Wistar rats were randomly divided into experiment group and control group. The distilled water was given in control group. 100 mg/L fluoride- was given in experiment group. After 8 weeks treatment, the rats were killed. Immunohistochemical staining was used to observe the expression of MMP-20 and TIMP-2 in rat incisors. Results  Immunohistochemical results demonstrated the presence of MMP-20 and TIMP-2 protein in ameloblasts, odontoblasts, stratum intermedium and the stellate reticulum of rat incisor. The imagination analysis results showed that the expression of MMP-20 was reduesed in experiment group（P<0.01）, and the expression of TIMP-2 had no significant difference（P>0.05）. Conclusion  The overdosed fluoride inhibits the secretion of MMP-20 and leads to the disturbed balance between MMP-20, TIMP-2 in rat incisor, which leads to the delay of the amelogenin removal and the enamel demineralization.

Key words:  fluoride, rat incisor, matrix metalloproteinase-20, tissue inhibitors of metalloproteinase-2