Micro-CT活体观察大鼠牙齿移动及复发过程的实验研究

目的:Micro-CT活体扫描连续观察不同矫治力引起的牙齿移动及复发的规律。方法:选择10周龄SD大鼠15只随机分成3组。对大鼠左侧上颌第一磨牙分别施加20 g、50 g、100 g的矫治力,持续加载14 d后卸载。在加力后的0、3、7、10、14 d和停止加力后3、7、10、14、28、42 d用Micro-CT对大鼠进行活体扫描,测量每个时间点牙齿移动的距离。结果:在加力后的0～3 d各组的磨牙都发生明显的近中移动,第3～10天,牙移动缓慢,第10天时20 g和100 g组移动距离快速增加。20 g组在矫治力去除后的0～3 d复发最多,50 g和100 g组在0～7 d复发最多,28 d几乎完全复发。结论:加载矫治力后牙齿呈现快速、缓慢、快速的移动规律,且轻力引起的牙移动更多。拆除加力装置的初期复发的最快,牙齿移动距离越大,复发越快。

In vivo Micro-CT Observation of Tooth Movement and Relapse in Rats.

Objective: To explore the law of tooth movement and relapse induced by different orthodontic forces through in vivo Micro-CT dynamic observation. Methods: Fifteen 10-week-old rats were divided into three groups randomly. Force of 20g, 50g and 100g were delivered to the first molars of left maxillary for 14 days. The Micro-CT scan was taken at day 0, 3, 7,10,14,28 after the appliance was applied and day 3, 7,10,14,28,42 after the appliance was removed.Thedistance oftooth movement at different time points was measured. Results: At first 3 days, the first molars of all groups mesially moved significantly. From day 3 to day 10, the tooth movement became slower. The 20g and 100g groups moved rapidly after day 10.In the 20g groups, the tooth movement relapsed significantly during day 0 to day 3, the 50g and 100g groups relapsed significantly during day 0 to day 7. At day 28, all groups almost completely relapsed. Conclusion: The process of tooth movement showed the pattern of an instantaneous displacement, delay, and a fast moving. The light force induced more tooth movement. The distance relapsed dramatically in the initial stage after the appliance was removed, and the greater the movement distance, the faster the relapse occurred.