Methods: Periapical lesions were induced in ovariectomized (OVX) and sham-ovariectomized (Sham) rats. After mandibles were collected, radiographs of periapical bone loss were evaluated using computer assisted image analysis to determine lesion size. And the enzymehistochemical test for tartrate-resistant acid phosphatase (TRAP) and immunohistochemical examination for P-p38 and RANKL were performed.
Results: On day 0, 7, 28, the numbers of osteoclast in the periapical areas of the OVX rats were significantly more than those of the Sham group. The data were shown statistic differences on day 0, 7, 21, 28 for P-p38 -positive cells and on day 7, 21, 28 for RANKL-positive cells between the two groups.
Conclusion:Estrogen-deficiency induced severe periapical bone resorption might be mediated by increased expression of RANKL. The p38 mitogen-activated protein kinase signal pathway might be involved into progressive bone resorption of apical periodontitis under estrogen deficiency.