The Effect Of Cortical Bone Osteotomy On The Periodontal Response And Tooth Movement Of Rat

Background and purpose: How to improve the efficiency of orthodontic and shortentreatment time, make the teeth more quickly and safely move in the jaw, is an issuesof orthodontics research and clinical practice. To ensure the physiological alterationsof dental periodontal tissue, orthodontic tooth movement speed can only bemaintained at a slower level, using the traditional treatment techniques, toothmovement speed was up to l mm/month, making the clinical orthodontic treatmentover long. If we can achieve fast, safe and efficient movement of teeth, theorthodontic treatment will be more popular.In recent years, researchers have produced abroad gradually accelerate therepair of local phenomena (Regional Acceleratory Phenomenon, abbreviated RAP)after fracture of the body in accordance with this principle, proposed corticotomysurgery used in orthodontic. This study hopes to establish an animal model ofcorticotomy, to provides the basis of experimental evidence for corticotomy.In this experiment, we introduce two cytokines: Interleukin-6(IL-6) and bonemorphogenetic protein-2(BMP-2), IL-6is a cytokine produced by activated T cellsand fibroblasts, After binding to the receptor on osteoclasts can promote theformation and recruitment of osteoclasts, plays an important role in bone resorption;BMP-2induce undifferentiated mesenchymal cells differentiation into bone andcartilage cell. Since these two cytokines for bone formation and resorptionrepresentative role, which changes according to the two cases can be speculated that the bone remodeling, which observed the effects of corticotomy on the boneremodeling.Methods:40male Wistar rats were randomly divided into two groups:20ratsserved as corticotomy surgery at left maxillary the first molar, and after1week wasserved conventional orthodontic appliance to move the teeth.20rats served asappliance control group, were just took the conventional orthodontic appliance at theright maxillary. Rats were killed and draw the material at the different points of time.We measured and compared the distance of maxillary the first molar of group A andgroup B, And using immunohistochemical S-P method to observe the expression ofinterleukin-6and bone morphogenetic protein-2of3groups. And we analyzed thedifferences of them using statistically analyzed.Results: The periodontal tissue changed obviously in corticotomy group. Boneresorption and formation appearance earlier and more activated in corticotomy groupthan other groups. The expression level of IL-6and BMP-2increased earlier andlasted for a longer time on the side of irradiation by coticotomy as compared to thoseon the control group. There was significant difference between the coticotomy groupand control group in terms of the IL-6and BMP-2expression intensity score at7、14das postoperation.Conclusions: In this study, we were established animal model of ratcorticotomy, the modeling method is simple, reproducible, and can be used in avariety of tooth movement and animal studies of corticotomy surgery. Thecorticotomy could accelerated the PDL remodeling and alveolar bone absorbing, alsopromotes new bone formation and accelerate orthodontic tooth movement. Thecorticotomy could induce partial restoration phenomenon (RAP). During themovement of orthodontic teeth,corticotomy could increase the expression level ofIL-6and BMP-2. It was suggested that the corticotomy can accelerate blood vessel and bone remodeling, shorten treatment time.