上颌反复扩缩前方牵引三维变化的锥形束CT分析

目的：利用锥形束计算机体层摄影术（cone-beam computed tomography, CBCT）探讨扩弓前牵对上颌标志点三维方向变化的影响，为骨性Ⅲ类错牙合畸形的早期治疗提供参考。方法： 选择36例上颌后缩患者，使用随机化区组设计分为反复扩缩组（alternating rapid palatal expansion and constriction group, RPE/C）和对照组（rapid palatal expansion group, RPE）， 各18例。RPE/C按照上颌快速扩弓两周、缩弓两周的顺序重复扩缩共10周，最后两周扩弓后行面罩前方牵引，RPE上颌快速扩弓两周后行面罩前方牵引，分别于治疗前（T1）、扩弓后（T2）、前牵后（T3）拍摄CBCT。利用Mimics 10.01软件进行颌面部三维重建、上颌标志点定点和测量分析。结果： RPE/C治疗结束上齿槽座点（subspinale, A）前移（3.06±1.29） mm，RPE（2.16±1.27） mm，组间差异具有统计学意义（P < 0.05）；RPE/C治疗各阶段标志点变化更对称；两组患者总治疗时间差异无统计学意义（P > 0.05）。RPE/C上颌骨性标志点矢状向、冠状向和水平向变化趋势：扩弓T2-T1阶段前下、增宽变化，前牵T3-T2阶段前上、缩窄变化，总治疗T3-T1阶段前下、增宽变化，其余测量项目组间差异无统计学意义（P>0.05）。结论： 上颌反复快速扩缩后前方牵引对早期治疗上颌后缩畸形有效；与上颌单次扩弓前方牵引的方法相比，上颌反复扩缩前方牵引对治疗中的上颌骨前移和对称性变化有利；CBCT在正畸测量分析中的应用需要进一步探讨。

Evaluation of maxillary three-dimensional changes in maxillary protraction with alternating rapid palatal expansion and constriction based on the cone-beam computed tomography

Objective： To use the cone-beam computed tomography (CBCT) to evaluate the three-dimensional (3D) changes of maxillary landmarks in the maxillary protraction with alternating rapid palatal expansion and constriction and with rapid palatal expansion, and to provide some clinical suggestions for the early treatment of Class Ⅲ malocclusion. Methods: A total of 36 maxillary retrusive patients were included and randomized in a 1 ∶1 ratio to either the intervention group (alternating rapid palatal expansion and constriction group, RPE/C) or the control group (rapid palatal expansion group, RPE). Randomization was accomplished with permuted block randomization based on participation sequence. The patients in the RPE/C were treated for 10 weeks (0.5 mm/d ) with the repetition of two-week palatal expansion and two-week palatal constriction. The patients in the RPE were taught to complete rapid palatal expansion for 2 weeks (0.5 mm/d ).The patients were instructed to come to the office for the follow-up to ensure the correct procedures. Damaged expanders were repaired (or replaced) and rebanded quickly. Sequential CBCT images including pretreatment (T1), post expansion (T2) and post-protraction (T3) were required for 3D reconstruction, establishment of landmarks, measurement and analysis by Mimics 10.01. Results: There was significant forward movement of subspinale (A) in the RPE/C after the treatment with (3.06±1.29) mm, compared with RPE (2.16±1.27) mm, P<0.05. There were more symmetrical changes of the landmarks in the RPE/C and there was no statistic significance of the entire treatment time between the two groups. Moreover, the maxillary skeletal landmarks had the following 3D changes of a forward and downward movement during the expansion stages T2-T1, a forward and upward movement during the protraction stages T3-T2 and a forward and downward movement during the total treatments T3-T1 compared with the control group. And the width between the bilateral landmarks increased during the expansion stages T2-T1, narrowed down during the protraction stages T3-T2 and increased during the total treatments T3-T1. Conclusion: The maxillary protraction with alternating rapid palatal expansion and constriction provided clinical benefits on maxillary advancement and symme trical changes in the orthopedic treatment of the patients with maxillary retrognathism and it required further study on the orthodontic analysis and measurements of CBCT.