A Study On The Effects Of Local Application Of OPG To The Orthodontic Teeth Movement Of Rats

The activity between the osteoblast and the osteoclast, with their mutual effects, influence the procedure of bone remodeling. The dynamic balance of bone formation and resorption maintains the completeness of the skeleton. The balance is regulated by some systemic hormones and cytokines. Recently, the discovery of osteoprotegerin (OPG) and osteoprotegerin ligand (OPGL) update the knowledge of the regulatory mechanism of the differentiation, maturity and function of the osteoclast. The inhibition of the differentiation and maturity of osteoclast will inhibit bone resorption. In the orthodontic therapy, the control of anchorage teeth movement is a difficult problem for orthodontists. If the alveolar bone resorption can be controlled through inhibition of osteoclast, the anchorage teeth movement will be effectively managed. The present study, based on the research of the influence of local OPG injection on the moving distance, the histological change of periodontal tissue and the number of osteoclasts of the experimental teeth, purports to argue the effects of local application of OPG to the orthodontic teeth movement in rats. The researcher simulated the anchorage tooth movement in the orthodontic therapy and established the zoic trial model. Forty ten-week-old SD(Spargue-Dewley) male rats with average weight of 250g to 300g are used. The nickel-titanium coil spring was placed between the incisor and the first molar on the right side of maxilla. Stretch force of 40g was produced to move the first molar mesialy. The recombined fused protein of rats'OPG and physiological saline were injected to the palatine-side mucoperiosteum of the first molar of the experimental group and the control group respectively. The injection and load were given at the same time. The moving distances were recorded in 1d, 4d, 8d and 12d respectively. The alveolar bone segment including the first molar was dissected and stained with HE and TRAP. The biological change of the periodontal tissue and the number of the osteoclasts were observed. The following results wereobtained:1. The moving distance of the maxillary first molar of the experimental rats is apparently lower than that of the control group at 8d and 12d (p<0.001).2. In the whole process of the experiment, the resorption of the alveolar bone in the pressure side of maxillary first molar of the experimental rats is lower than that of the control group.3. The number of osteoclast in pressure side of the distal root of maxillary first molar is obviously less in experimental group than in control group at 4d, 8d and 12d (p<0.001).