Objective To explore the relationship between serum matrix metalloproteinases (MMP-2, MMP-9, and MMP-13) expressions and dental fluorosis in fluorine exposed population.
Methods A total of 191 individuals were selected from an area of endemic fluorosis in Guizhou Province. Urinary fluoride level was quartilized based on the range of urinary fluoride in local population (<1.2 mg/gCr, 95 cases; 1.2 mg/gCr~, 43 cases; 1.8 mg/gCr~, 24 cases; and 2.4 mg/gCr~, 29 cases). The participants were classified as normal (34 cases), suspect+very mild (37 cases), mild (33 cases), moderate (56 cases), and severe (31 cases) according to the diagnostic criteria of dental fluorosis. Urinary fluoride concentrations were determined by ion-selective electrode. Serum levels of MMP-2, MMP-9, and MMP-13 were measured by enzyme-linked immunosorbent assay (ELISA).
Results ① The expression of MMP-2, MMP-9, and MMP-13 increased gradually with the increasing of urinary fluoride level. There were significant differences in MMP-2, MMP-9, MMP-13 expressions between Groups 1.2 mg/gCr~, 1.8 mg/gCr~, 2.4 mg/gCr~ and Group <1.2 mg/gCr (P < 0.05), and between Group 2.4 mg/gCr~ and Group 1.2 mg/gCr~ (P < 0.05). The expression levels of MMP-2 and MMP-9 in Group 2.4 mg/gCr~ were significantly different from Group 1.8 mg/gCr~ (P < 0.05). ② The severity of dental fluorosis increased significantly with the increase of MMP-2, MMP-9, and MMP-13 expressions. Compared with the normal group, MMP-2, MMP-9, MMP-13 was increased significantly in the moderate and the severe groups (P < 0.05). Significant differences were also found between the severe group and the suspect+very mild group (P < 0.05). ③ Urinary fluoride concentrations were positively correlated with the expression levels of MMP-2, MMP-9, and MMP-13 (r=0.808, r=0.795, and r=0.790, respectively, P < 0.05). The severity of dental fluorosis were positively correlated with the MMP-2, MMP-9, and MMP-13 activity (r=0.332, r=0.358, and r=0.316, respectively, P < 0.05).
Conclusion Through the induction of MMP-2, MMP-9, and MMP-13 expressions, fluorine can intervene the regulation of bone metabolism and lead to development and progression of dental fluorosis.
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