Animal Experimental Study On The Periodontally Accelerated Osteogenic Orthodontics

Objective : We study Periodontally Accelerated Osteogenic Orthodontic(PAOO)-facilitated tooth movement on rats by evaluating the gene expression of osteogenesis-related factors and the Micro CT imaging of alveolar bone around the mesial root of the maxillary first molar,aiming to investigate the effect of PAOO on alveolar bone mineral density and bone remodeling,thus providing a theoretical and experimental model for accelerating tooth movement and bone remodeling in orthodontics.Methods: Forty-two SPF male Sprague-Dawley(SD)rats were randomly divided into three groups: a TM group(n=18),a PAOO group(n=18),and an untreated control group(n=6).The rats in TM and PAOO groups were randomly divided into three groups which applied orthodontic force for 3,7 and 14 days.The upper 1st molar of TM and PAOO groups was protracted using 30 g of orthodontic force.No orthodontic appliances were installed in the untreated control group.After 3,7,and 14 days,animals in each group were sacrificed.Osteogenic differentiation was confirmed by real-time quantitative reverse transcription PCR(q RT-PCR)examination of Runx2,micro RNA-30 d,etc.The imaging changes of bone tissue were evaluated,and the trabecular structure parameters were measured by Micro CT.Multi-way ANOVA was performed on the data with P < 0.05.Results:1.The expression of mi R-30 d and Runx2 in the alveolar bone of the PAOO changed as time goes by compared with the TM group,the expression of mi R-30 d decreased significantly after reaching the peak on the 3rd day.The expression of Runx2 in PAOO group and TM group increased,and the expression level was different at each detection time point.2.According to Micro CT: the periodontal ligament changed from a smooth circle to radiate;the low-density image around the root was broadened with the enlarged periodontal ligament space;the alveolar bone in the direction of tooth movement was absorbed.The bone volume fraction of PAOO group decreased significantly,while that of TM group increased gradually after the first three days of decrease.There are statistically significant differences between the two groups and each time point(P<0.05).Conclusion: 1.mi R-30 d may involve in the process of alveolar bone formation during PAOO orthodontic tooth movement in rats by inhibiting the expression of Runx2.2.PAOO accelerates orthodontic movement by reducing alveolar bone mineral density and accelerating bone remodeling.