[Clinical efficacy of clear aligners in treating bimaxillary protrusion].

Objective: To evaluate the efficiency of clear aligners in treating bimaxillary protrusion patients with first premolar extractions. Methods: Eleven patients with bimaxillary protrusion were selected in this study. All of them were treated by using clear aligners with four first premolar extractions and need maximal anchorage. Cephalometric analysis was carried out before and after treatment. Results: Cephalometric analysis results showed that significant changes in teeth and profile could be detected after clear aligner treatment and no change could be found in skeletal pattern. Upper and lower anterior teeth were retracted. The control of anterior torque and posterior anchorage were effective. The soft tissue analysis showed that position of upper and lower lip was significantly changed which improve the profile of patients. After treatment, the distance of U1 to NA and L1 to NB reduced by (5.19±4.12) mm and (4.53±1.20) mm, respectively. The differences were statistically significant (P<0.01). Conclusions: Bimaxillary protrusion patients who needed premolar extractions and maximal anchorage could be treated with clear aligners.目的： 探讨无托槽隐形矫治技术减数矫治双颌前突的临床疗效。 方法： 选择2011年11月至2013年7月就诊于北京大学口腔医学院·口腔医院正畸科的双颌前突恒牙 期错 畸形患者11例，年龄（25.4±7.3）岁，采用减数4颗第一前磨牙强支抗设计，运用无托槽隐形矫治技术进行矫治。分析矫治前后X线头影测量项目的变化。 结果： 与矫治前相比，矫治后骨性测量项目未见明显变化，而牙性测量项目均发生显著改变，上下颌前牙明显内收，矫治后U1-NA距（上中切牙切缘至鼻根点-上牙槽座点连线的垂直距离）减少（5.19±4.12）mm，L1-NB距（下中切牙切缘至鼻根点-下牙槽座点连线的垂直距离）减少（4.53±1.20）mm，上唇凸点至E线距离减小（2.59±1.15）mm，下唇凸点至E线距离减少（4.25±1.87）mm，鼻唇角增加9.84°±10.34°。矫治后患者垂直向高度均得到良好控制，下颌平面发生一定程度的逆时针旋转，有效改善了患者的侧貌面型。 结论： 使用无托槽隐形矫治技术，设计减数第一前磨牙以及后牙强支抗，可有效内收上下颌前牙，从而使患者软组织侧貌得到显著改善。.