Micro-CT对骨皮质切开术中区域性加速现象的分析

Analysis of Regional Accelerated Phenomenon in Corticotomy-assisted Orthodontic Treatment by Micro CT

目的：Micro-CT观测骨皮质切开辅助正畸治疗中牙齿移动速率和牙槽骨结构的改变。方法：选用75只4~6周龄的雄性SD大鼠,随机分为3组：组1：牙槽骨皮质切开辅助正畸（CO＋TM）,组2：传统正畸（TM）,组3：单纯牙槽骨皮质切开（CO）,按照时间点（加力4、7、14、21、28d后）处死实验动物并进行Micro-CT扫描,测量牙移动距离;三维重建后测量牙颈部、根中部、根尖部3个平面张力侧及压力侧共6个区域的牙槽骨骨密度及骨体积。结果：1）牙移动距离：初期TM组高于CO＋TM组,在第14、21、28天时,CO＋TM组明显高于TM组（P〈0.05）。速率：4~7d时TM组大于CO＋TM组,之后小于CO＋TM组,组间比较P〈0.05。2）骨密度：4、7、21、28d时远中骨密度CO＋TM组与CO、TM组比较持续下降,TM组则先下降后上升,CO组稳定于0左右（P〈0.05）。3）骨体积：CO＋TM组近中骨体积始终呈下降趋势,TM组近中骨体积自加力4d后持续缓慢升高。结论：牙槽骨骨皮质改良切开术辅助正畸可以在术后14~28d内增加正畸牙移动距离;牙槽骨远中侧骨密度降低明显,压力侧骨体积下降,张力侧骨体积上升,骨改建活跃,区域性加速现象在21d时最明显。

Objective：To observe the rate of tooth movement and the structure of alveolar bone in corticotomy-assisted orthodontic treatment by Micro-CT.Methods：75four or six-week male SD rats were used in this study.The rats were randomly divided into 3groups：group1-CO＋TM,group2-TM,group3-CO,with 5in each one group.The rats were sacrificed at different times（t=4,7,14,21,28days）.Micro-CT was used to measure the change of tooth movement and the structure of alveolar bone.Results：In terms of the amount of tooth movement,our results illustrated that the CO＋TM group had a small amount at the beginning of the study compared with the TM group,CO＋TM group was obvious higher than TM group from day 14 to 28（P〈0.05）.From day 4to 7,TM was faster than CO＋TM,then slower than CO＋TM.When compared to CO and TM,CO＋TM continued to drop at day 4,7,21,28.TM group went up at first and then went down.CO group was stable at 0（P〈0.05）.The bone volume in mesial of CO＋TM group always decreased.As to TM group,the volume decreased in the early,but rebound after the 4th day.Conclusion：Alveolar bone corticotomy-assisted orthodontic treatment can accelerat the rate of tooth movement from day 14 to 28.There is a phenomenon called ＂regional accelerated phenomenon（RAP）＂ occured at day 21,It is associated with increased perfusion and bone turnover and decreased bone density.