应用Micro-CT研究矫治力对正畸牙齿移动及牙根吸收的影响

目的：了解不同矫治力作用下大鼠牙齿移动距离及牙根吸收情况，探索应用Micro?CT研究正畸牙齿移动过程中矫治力对牙根吸收的影响。方法10周龄健康雄性SD大鼠64只（220~270 g），分别施以10 g （10 g力组）、30 g力（130 g力组）拉右侧上颌第一磨牙向近中移动建立实验动物模型，以对侧同名牙为对照牙。于加力后第3、7、14、28天处死动物，使用Micro?CT扫描上颌第一磨牙及周围牙槽骨，测量上颌第一磨牙近中移动距离，计算加力28 d上颌第一磨牙近中根的表面凹陷体积，进行统计学分析。结果加力后发生牙齿移动，10 g力组在加力14 d内，牙齿移动量小于30 g力组（P =0.039），在加力28 d时大于30 g力组（P<0.05）。加力28 d，10 g力组、30 g力组的牙根表面凹陷总体积高于对照组（P=0.004），30 g力组产生的牙根表面凹陷总体积高于10 g力组（P<0.001）。结论 Micro?CT可以对牙齿移动及牙根吸收进行可靠评价及量化分析。加力后28 d，10 g力组移动量较30 g力组大，相应产生牙根吸收较30 g力组少。

Micro-CT study of the influence of orthodontic force on the root resorption and orthodontic tooth movement

Objective To analyze the tooth movement distance and root resorption in rats under different orthodon?tic forces, to explore the effect of orthodontic force on the root resorption during orthodontic tooth movement. Methods 64 male Sprague Dawley (SD) rats aged 10 months weighting 220?270 g in this study. 10 g and 30 g nickel?titanium closed?coil springs were applied mesially to the maxillary right first molars, while contralateral first molar was severed as a control. At day 3, 7, 14 and 28 after loading, the molars were extracted. The tooth movement distance and the vol?ume on the surface area of root resorption were measured and scaned by Micro?CT. Results Tooth movement gradually increased after loading. For 10 g group, 30 g group showed farther tooth movement distance with time throughout 14 days (P = 0.039), but there was a reverse result at day 28 (P<0.05). There was a significant increased in the root re?sorption craters between the control group and the 10 g/30 g group after 28 days of loading (P=0.004), and the deeply root resorption were observed on the 30 g group (P<0.001). Conclusion Reliable evaluation and quantitative analysis in the tooth movement and the root resorption could be done by Micro?CT. Tooth movement in the 10 g group was more rapid than the 30 g group, nevertheless, the root resorption craters was less reduced after 28 days loading.