Heavily Induced Root Resorption Stimulates Wnt5a Expression in Cementoblasts

Abstract

Wnt signaling plays a vital role in bone metabolism. However, currently, its role in bone formation and resorption during orthodontic tooth movement is still unclear. This study aimed to investigate in vivo Wnt5a expression in the resorbed root in rats during experimental tooth movement. Eighteen 6-week-old, male Wistar rats were subjected to an orthodontic force of 10 or 50 g for 7 days to induce the mesial movement of the upper first molars. Immunohistochemical analysis was performed to assess tartrate-resistant acid phosphatase, receptor activator of nuclear factor-B ligand(RANKL), and Wnt5a protein expressions in the alveolar bone. Additionally, the effects of different compression forces (CFs)on Wnt5a production were investigated using human periodontal ligament(hPDL) cells and human cementoblast-like cells in vitro. Resorption lacunae with multinucleated cells in the CF-10 g group under experimental tooth movement conditions in vivo. Moreover, RANKL and Wnt5a immunoreactivity was detected in the alveolar bone-PDL tissues. In the CF-50 g group, resorption lacunae and RANKL and Wnt5a expressions were detected in PDL-cement tissues. In the in vitro study, 1.0-and 4.0-g CF increased Wnt5a production in hPDL cells and HCEMs, respectively, in a time-dependent manner. These results indicate that the Wnt signaling response to heavy orthodontic forces stimulates the root resorption process during orthodontic tooth movement.