舌侧矫治不同加力方式关闭拔牙间隙的三维有限元研究

Three-dimensional finite element study on closing tooth extraction clearance in lingual correction by different loading methods

目的:建立舌侧矫治三维有限元模型,分析舌侧矫治关闭拔牙间隙时颊腭侧不同加力方式和不同牵引钩长度对牙周膜应力情况和牙齿移动趋势的影响。方法:选取1名健康成年志愿者,建立三维有限元模型,分别模拟A组单纯腭侧加力1. 5 N、B组颊侧1. 0 N+腭侧0. 5 N、C组颊侧0. 5 N+腭侧1. 0 N、D组颊腭侧各0. 75 N 4种加力方式,并结合2 mm、3 mm、4 mm、5 mm 4种长度牵引钩,建立16组工况。分析比较颊腭侧不同加力方式和不同牵引钩长度对牙周膜的应力分布和牙齿移动趋势的影响。结果:A组牙周膜应力值均高于其余3组。其余3组中,牙周膜最大应力值随着牵引钩的增长呈现降低趋势,工况D4牙周膜最大应力值最低。除去A组,其余3组中,中侧切牙X轴方向位移值均随着牵引钩的增长而逐渐减小,舌倾得到改善,其中工况D4前牙舌倾趋势最弱。颊腭侧同时加力组较单纯腭侧加力组,水平向和垂直向的"拱形效应"显著改善。结论:在舌侧矫治系统关闭拔牙间隙时采用颊腭侧同时加力,并延长牵引钩,能降低牙周膜应力水平,有效改善前牙舌倾,利于牙齿的整体移动趋势。

Objective: To establish a three-dimensional finite element model of lingual orthodontics,and to analyze the effects of different loading modes and different length of traction hook on the stress distribution of periodontal membrane and tooth movement trend during lingual orthodontic closure of extraction space. Methods: A healthy adult volunteer was selected to establish a three dimensional finite element model,four kinds of loading methods were simulated respectively that group A with palatal side 1. 5 N,group B with buccal side 0. 5 N + palatal side 1 N,group C with buccal side 1. 0 N + palatal side 0. 5 N and group D with buccal side 0. 75 N + palatal side 0. 75 N respectively. And combined with 2 mm,3 mm,4 mm,5 mm length traction hook respectively,16 groups of working conditions were established. The effects of different loading modes and different length of traction hook on the stress distribution and tooth movement trend of periodontal ligament were analyzed and compared. Results: The stress values of periodontal ligament in group A were higher than those in the other three groups. In the other three groups,the maximum stress value of periodontal membrane decreased with the increase of traction hook. The maximum stress value of periodontal membrane in working condition D4 was the lowest. Except for group A,the displacement values of X axis in the other three groups decreased gradually with the increase of the traction hook,and the tongue inclination was improved. Among them,the tongue inclination trend of anterior teeth in condition D4 was the weakest. In the buccal palatal side of the three groups at the same time,horizontal and vertical direction of the ' arch effect' trend significantly improved. Conclusion: The application of buccal and palatine force and the extension of traction hook in closing the extraction space of the lingual correction system can reduce the stress level of periodontal membrane and effectively improve the lingual inclination of the anterior teeth,which is beneficial to the overall movement of the teeth.