无托槽隐形矫治器联合微种植钉整体内收上前牙的三维有限元研究

Combined use of miniscrews and clear aligner for en-mass retraction of maxillary anterior teeth: A finite element analysis

目的:探讨隐形矫治器联合微种植钉整体内收上前牙时不同加力方式下上颌前后牙生物力学效应。方法:采集患者上颌骨及上牙列的CBCT数据,采用逆向工程方法建立拔除第一前磨牙的隐形矫治器联合微种植钉整体内收前牙的三维有限元模型,分析①矫治器施力、②矫治器施力+1. 47 N力牵引矫治器、③矫治器施力+1. 47 N力牵引尖牙工况下前后牙的初始位移。结果:3种工况条件下矢状方向,中切牙冠根位移差分别为1. 12E-02 mm、1. 29E-02 mm、9. 62E-03 mm;第一磨牙牙冠近移量分别为-2.49E-02 mm、-2.09E-02 mm、-2.00E-02 mm;垂直方向,中切牙牙冠伸长量分别为1. 77E-03 mm、2. 93E-03 mm、6. 53E-04 mm。结论:工况③更有利于切牙转矩的控制及后牙支抗保护,也更有利于切牙的垂直向控制。

Objective: To evaluate the biomechanical effects of combined use of miniscrew and clear aligner in different kinds of loading condition on the en-mass retraction of maxillary anterior teeth. Methods: 3 D finite element models of the maxillary bone with miniscrews and clear aligner were reconstructed using the method of reverse engineering with CBCT data of an adult patient who had maxillary first premolars extracted. The orthodontic force was loaded by(1)clear aligner,(2) clear aligner and 1. 47 N force of retraction at appliance and(3) clear aligner and 1. 47 N force of retraction at canine,respectively. Results: Under the working condition of(1),(2)and(3),in sagittal direction,the displacement difference of crown and root of the maxillary central incisor was 1. 12 E-02 mm,1. 29 E-02 mm and 9. 62 E-03 mm respectively,the displacement of the first molar crown was-2. 49 E-02 mm,-2. 09 E-02 mm and-2. 00 E-02 mm respectively;in vertical direction,extrusion of the maxillary central incisor was 1. 77 E-03 mm,2. 93 E-03 mm and 6. 53 E-04 mm respectively. Conclusion: The working condition(3) is more advantageous to control the torque of incisors and to save the anchorage of posterior teeth,and more effective to control the extrusion of the incisors.