Effects of bisphosphonate and indomethacin on alveolar bone remodeling in rats

Cho, Myeong Sook; Kim, Jong Chul

Abstract

The purpose of this study was to examine the effects of bisphosphonate and indomethacin, blockers of bone resorption with different mechanisms, on alveolar bone remodeling. Male rats were divided into control, bisphosphonate and indomethacin groups, and then each group was divided into an experimental side and a control side according to the force application. Bisphosphonate(6.3/kg, 2.52x10(-2)mol/L) and indomethacin (9mg/kg, 2.52x10(-2)mol/L) were injected 6 hours and 1 hour before or 24 hours after the force application. The rats were killed 72 hours after the force application and histologic examination was performed. The values of serum acid phosphatase and lactate dehydrogenase were also measured in the control and experimental groups treated with bisphosphonate or indomethacin 1 hour before the force application. In the experimental side, the least number of osteoclasts was noted in the groups treated 1 hour before the force application with indomethacin or bisphosphonate, while there were no differences between the control and the groups treated with drugs 6 hours before or 24 hours after the force application. In the control side, the number of osteoclasts was not inecreased with no differences among the groups. Histologic examination revealed a severe alveolar bone resorption in the control group and the groups treated with indomethacin 6 hours before or 24 hours after the force application. Indomethacin treatment 1 hour before the force application and bisphosphonate treatment at any time significantly attenuated the bone resorption. Electron microscopically, ruffled border and clear zone of osteoclasts were observed in the control and indomethacin groups, while some osteoclasts were detached from the bone surface and exhibited dull cellular projections in the bisphosphonate groups. The bisphosphonate and indomethacin groups showed lower values of acid phosphatase and lactate dehydrogenase than the control group. The acid phosphatase value in the bisphosphonate group was lower than that in the indomethacin group, whereas there was no difference in the lactate dehydrogenase value between the groups. These results suggest that bisphosphonate reduces the activity of osteoclasts as well as the number of osteoclasts and that indomethacin reduces the number of osteoclasts without affecting the activity of osteoclasts. Bisphosphonate has a larger inhibitory effect on bone resorption and thus less limitation in the application time than indomethacin.