Oral bone loss is increased in ovariectomized rats

Alveolar bone loss associated with periodontal disease occurs frequently in postmenopausal females, the same group that is predisposed to osteoporosis. To determine if the estrogen-deficient state enhances oral bone loss, we studied ovariectomized rats administered the potent bone-resorbing cytokine interleukin-1 or the periodontal pathogen Campylobacter rectus lipopolysaccharide (LPS). Distal root canals of first mandibular molars were instrumented with endodontic files, and bone resorbing factors were deposited and sealed into the root canal. Radiographs of periapical bone loss were evaluated using computer assisted image analysis to determine lesion size. Both interleukin-1 and C. rectus LPS caused a significant increase in lesion area in both ovariectomized and normal rats when compared with controls and a significant increase in ovariectomized animals compared to nonovariectomized animals receiving LPS. Using this endodontic model, we have demonstrated that estrogen deficiency results in increased oral bone loss in rats.