牙齿移动过程中牙槽骨显微结构动态变化的微型CT研究

Evaluation of periodontal tissue during orthodontic tooth movement in rats： a micro-computed tomography study

目的 通过微型CT探讨正畸牙齿移动过程中矫治力对牙槽骨骨小梁的影响规律,以期为正畸临床提供参考.方法 选择10周龄SD雄性大鼠10只建立实验动物模型,施加0.196 N矫治力,近中移动上颌第一磨牙,分别于加力前、加力后第3、7、14 d对大鼠上颌牙槽骨骨小梁进行微型CT扫描,计算骨体积分数、骨表面积体积比、结构模型指数、骨小梁厚度、骨小梁数目及骨小梁间隙,并进行随机区组多因素方差分析.结果 施加矫治力后第7天压力侧牙槽骨骨体积分数[（41±14）%]比第3天[（64±15）%]显著减少（P＜0.05）,结构模型指数（1.51±0.52）和骨小梁间隙[（90±30）μm]比第3天[分别为（0.51±O.85）、（56±10）μm]显著增大（P＜0.05）;加力第14天张力侧牙槽骨骨体积分数[（78±14）%]比第7天[（67±14）%]显著增大（P＜0.05）,结构模型指数（0.28±0.20）和骨小梁间隙[（29±13）μm]比第7天[（0.40±0.41）和（48±15）μm]显著减小（P＜0.05）,压力侧和张力侧牙槽骨骨小梁数目各时间点间差异无统计学意义（P＞0.05）.结论 在正畸矫治力作用下,牙根压力侧牙槽骨骨质吸收开始于加力后第7天,张力侧骨质形成开始于加力后第14天.

Objective To observe the microstructure changes of rat alveolar bone around tooth root under orthodontic force loading. Methods Ten 10-week-old rats were included in the study. Upper first molars were moved mesially with 0.196 N of force. The alveolar bone around the root of upper first molar was scanned by a micro-computed tomography scan system（SkyScan-1076） in different period after the initiation of orthodontic force loading（ on the 3rd, 7th, 14th day after force loading ） and analyzed by a speciallydesigned software to measure the microstructure parameters of alveolar bone （ bone volume fraction, bone surface to volume ratio, structure model index, trabecular thickness, trabecular separation, trabecular number）. Results From the 7th day, bone volume fraction[（41±14）%], structure model index（ 1.51 ±0. 52） and trabecular separation [（90 ± 30 ） μm] changed significantly in the compressive area compared with those[（64±15）%, （0.51 ±0.85）, （56 ±-10） μm] on the 3rd day. From the 14th day, bone volume fraction[（78 ± 14）%], structure model index（0. 28 ± 0. 20） and trabecular separation[（29 ±13） μm] changed significantly in the tension area compared with those[（67 ± 14）%, （0.40 ±0.41 ）,（48 ± 15） μm] on the 7th day. No difference on trabecular number was found between the compressive area and tension area（P ＞0. 05）. Conclusions The significant resorption of the alveolar bone was observed on the 7th days in the compressive area and the deposition of the alveolar bone was observed on the 14th day in the compressive area after orthodontic force loading.