Denervation delays initial bone healing of rat tooth extraction socket

Functions of nerves on bone has been a subject of intense research. The aim of this study is to observe initial bone healing of rat tooth extraction socket after inferior alveolar nerve transection. The bilateral mandible second molars of eighteen Wistar rats were extracted in the study. The rats also suffered from right inferior alveolar nerve transection simultaneously (D + E group), only extraction as control (E group). One, two and four weeks after extraction, the mandibles were taken out for histological observation, TRAP staining, immunofluorescence, immunohistochemistry and micro-computed tomography (Micro-CT). Mouse bone marrow derived macrophages (BMMs) were cultured in vitro. Expressions of nuclear factor erythroid 2-related factor 2 (Nrf2) were detected in vivo and vitro. The alveolar sockets had been filled to a large extent with new bone at 4 weeks, but BV/TV and BMD decreased in the D + E group. Accordingly, Expressions of osteocalcin (OCN) and osteopontin (OPN) were down-regulated in the D + E group. Denervation increased TRAP-positive osteoclasts and decreased expressions of Nrf2 at 2 weeks after extraction. Decreased Nrf2 promoted osteoclast differentiation of BMMs in vitro. Denervation delays initial bone healing of rat tooth extraction socket. Osteoclast activation induced by decreased Nrf2 might participated in the process.