OBJECTIVEThis study aimed to investigate the expression function of substance P and the formation of osteoclasts in the periodontal tissues after the inferior alveolar nerve sectioned in rats.

METHODSThirty Wistar male rats were used in the experiment and were divided into six groups (n = 5) randomly: 0 d (normal), 3 d, 7 d, 14 d, 21 d, and 28 d. The periodontal tissues were removed from the denervation of the inferior alveolar nerve in rats. The periodontal tissues were checked by paraffin sections through immunohistochemical staining to trace the expression of substance P and through tratrate resistant acid phosphatase (TRAP) staining to detect the osteoclasts. The average optical density and osteoclast were measured, and the obtained data was statistically analyzed.

RESULTSThe expression level of substance P in the first three days decreased significantly after the inferior alveolar nerve was cut. In addition, the lowest expression level was measured after 7 d. Normal levels in the periodontal tissue were measured after 21 d. In addition, we found that osteoclasts vary proportionally with the changes in substance P.

CONCLUSIONThe changes in substance P is positively correlated with the quantity of osteoclasts after the inferior alveolar nerve section. Therefore, we deduce that substance P may regulate the differentiation of osteoclasts formation, and thereby participate in the balancing of aveular bone metabolism.