Purpose: In order to systematically study the role that Cbfa1 palyed during the whole process of bone resorption, a tooth movement model in beagle-dog was established to examine in vivo the mechanically induced Cbfa1 protein and its expressions during the process of bone remodeling in orthodontic treatment.
Materials and Methods: Orthodontic force was applied continuously for 16 weeks after installing of orthodontic appliances in the beagle dogs. The coiled spring was reactivated at 4-week’s intervals. One dog was sacrificed each time at 1, 2, 3, 4, 8, 12, 16 weeks after force application. The involved teeth with surrounding bone and periodontal tissues were harvested. Then 5µm tissue sections for immunohistochemistry examinations were prepared routinely, and the expressions of Cbfa1 protein at different stages were examined by means of IHC.
Results: Cbfa1 protein was identified in the periodontal tissues during the whole process of tooth movement. The immunoreactivities were detected both in the cytoplasma of OBs and in the extracellular matrix of PDLs. It was unexpected that Cbfa1 protein was also deteced in the cytoplasm of OCs at 4 weeks time after the force application.
Conclusions: Cbfa1 may be a key molecule controlling the osteogensis during orthodontic tooth movement. Cbfa1 expressed in osteoclasts may have a self-regulatory role in the motility, adhesion, resorptive activity, and survival of the cell. However, further studies were needed to investigate the exact reason for the discrepancy between the RANKL protein and the mRNA expression.