Background Wnt signaling is valuable protein network involved in bone metabolism; however, its relationship in bone resorption and formation during orthodontic treatment is currently unknown. Purpose This study examined Wnt5a expression on the compression side in an in vivo experimental rat tooth movement model. The study then investigated the relation of compression force(CF)to Wnt5a expression from human periodontal ligament(PDL)cells. Material and Methods In vivo, to movement the maxillary first molar, we added 10 g of orthodontic force to twenty male rats for seven days. We assessed the production of tartrate-resistant acid phosphatase (TRAP) and Wnt5a protein in rats alveolar bone through an immunohistochemical analysis. In vitro, we examined the effect of compression force(CF)on Wnt5a expression using the human PDL(hPDL)cells. Results We observed resorption lacunae with the multinuclear cells in rat alveolar bone during tooth movement in the 10g group. We observed Wnt5a immunoreactivity on day seven with orthodontic force in the PDL tissue. Wnt5a expression increased for timedependent maner after addition of CF in hPDL cells. Conclusion Given these findings, the Wnt signaling response to optimum orthodontic force appears to stimulate resorption of alveolar bone in the orthodontic tooth movement.

This study aimed to evaluate the effect of CT values of the tooth root and bone on root resorption using data obtained before and after orthodontic treatment. Fortyone patients with jaw deformities were divided into those with and without root resorption (n = 18 and 23, respectively) . The distance from the anatomical root apex to the edge of the incisive canal was measured using axial CT sections before active treatment.The distance from the anatomical root apex to the labial and palatal cortical bone and the CT values of the root and alveolar bone were measured and compared using sagittal CT sections. The tooth axis and vertical and lateral movements of the maxillary right central incisor were examined using lateral cephalograms before and after treatment. Root resorption group showed significantly higher CT values of alveolar bone than the control group and different axial movement of the root apex and distance between the labial cortical bone and root apex on lateral cephalograms. The risk of root resorption increased with an increase in the CT values of the alveolar bone surrounding the maxillary central incisor. The horizontal movement of the root apex was associated with the distance between the labial cortical bone and root apex, and root resorption during maxillary central incisor movement.

No abstract