The effect of fluoride on the bone formation of embryonic chicken in vitro

Objective To observe the effective of fluorid e on the bone formation in vitro and to explore the mechanisms of fluorosis.Methods The femur of chicken was cultured with fluorid e in various concentrations(120,240,480,960 μmol/L)for 11 days, then morpholo gic changes and calcification of cells were examined; apoptosis was detected by terminal deoxyribonucleotide transferase-mediated dUTP-bintin(TUNEL) method, a nd the apoptotic index(AI,%) was calculated; the ultrastructural changes of chon drocytes were observed with electron-microscope; at the same time the contents of H 2O 2,NO and SOD in the culture were tested.Results The mean values of calcification area, general light dense and sum light dense of fluoride-treated groups were higher than tho se of the control( P0.05). The AI(%) of fluoride-treated groups was remark ably different as compared with the control (P0.05 and P0.01). It was observed there were apoptotic cells or apoptotic bodies in cells with electron -microscope. The H 2O 2 content increased in media of groups-treated with fl uoride above 240 μmol/L. (the differences were significant when compared with t he fluoride free control);the NO content in all fluoride-treated groups was mar kedly higher than that of the control group (P0.01); the SOD activity was lower in all fluoride- treated groups (P0.05) except for 120 μmol/L tha n that of control.Conclusions In vitro, fluoride promote apoptosis,calci fication and ossification. This is probably the mechanism by which osteofluorosi s occurred. Excessive free radicals might be responsible for the abnormal occurr ence of apoptosis, hence the excessive bone formation in case of fluorosis.