Effects of ovariectomy on turnover of alveolar bone in the healed extraction socket in rat edentulous mandible

Objective: The number of patients with postmenopausal osteoporosis receiving dental implants because of edentulism is increasing. Since osseointegration around implants requires formation and maintenance of new bone, knowledge of how ovariectomy (OVX) affects turnover of mandibular and maxillary bone is required. In the present study, we investigated the effects of OVX on turnover of alveolar bone in the healed extraction socket of the rat left mandibular incisor. Methods: The molars and the incisor on left side in 6-month-old Sprague-Dawley female rats (n = 38) were extracted and left to heal for 4 months. Animals were then ovariectomized and killed at the time of OVX (baseline) (n = 4), 6 weeks (n = 10), 6 months (n = 12) and 9 months (n = 12) post-OVX. Changes in bone mass and bone turnover were assessed using static and dynamic histomorphometric parameters. Results: Bone turnover was increased by ovariectomy (OVX) as reflected by increased static parameters of bone formation and resorption. The changes in dynamic parameters were not statistically significant. Cancellous bone volume/total volume (%) in the post-OVX group decreased more than that in the control group. Conclusions: Our results suggest that OVX increases the turnover of alveolar bone in the healed extraction socket of rat mandibular incisor, resulting in a decrease of cancellous bone volume with time.