正畸牙根吸收过程中牙根三维形态的MICRO-CT初步研究

A pilot study on three dimensional morphology of root by Micro-CT during orthodontic root resorption

目的了解不同的矫治力作用下牙根表面的三维形态学特征变化,探索正畸牙根吸收过程中矫治力值对牙根吸收的影响规律。方法选择11周龄的SD雄性大鼠22只,分别施加100g和30g近中移动上颌第一磨牙建立实验动物模型,以对侧同名牙作为对照牙。2周后处死动物,获得上颌第一磨牙及其周围牙槽骨。使用Skyscan 1172型Micro-CT扫描大鼠上颌第一磨牙,计算大鼠上颌第一磨牙近中根的表面凹陷体积并进行统计学分析。结果施加矫治力2周后,重力组与轻力组在牙根表面凹陷总体积上没有显著性差异,但是二者都显著高于对照组。在牙根上段近中面的凹陷体积上,轻力组显著高于重力组和对照组。在牙根下段远中面,重力组显著高于对照组(P<0.01)。结论施加矫治力后,发生牙根吸收,但是在本实验的研究周期中,力值对牙根吸收的程度无明显影响,对吸收的部位有影响。在重力作用下,牙根吸收主要发生在牙根下段远中面。而在轻力作用下,牙根吸收主要发生在牙根上段近中面。

Objective To analyze the three dimensional morphology of root surface,and try to investigate the effect of the magnitude of force on root resorption during orthodontic tooth movement.Methods The animal model was set up by applying on the upper first molars of 22 SD rats with 100g and 30g forces for 2 weeks.Then the teeth and the alveolar bone around teeth were scanned,and calculated,the volume of the mesial root of maximal first molars was analysed.Results When the teeth were applied force for 2 weeks,the whole resorption volume of experimental groups increased significantly than that of the control group,the resorption volume on the lower distal surface of 100g group increased significantly than that of the control group,and the volume on the upper mesial root surface increased significantly than that of the control group.（P〈0.01）,while there was no significant difference between the 30g group and 100g group.Conclusion Force can result in root resorption.And the magnitude of forcewas not related to the extent of root resorption during 2 weeks,but it was related to the position of root resorption.When the teeth were applied 100g force,the root resorption was observed on distal surfaces of lower part,while that was observed on the upper mesial surfaces of roots with 30g force.