不同支抗形式受力后上颌第一磨牙牙周膜应力分布的三维有限元分析

Effect of different anchorages on stress distribution in periodontal ligament of upper first molar: a three-dimensional finite element analysis

目的通过三维有限元方法,建立不同支抗形式的三维有限元模型并模拟牙齿的受力移动,从而比较不同支抗形式下上颌第一磨牙的牙周膜的应力分布。方法建立含有不同支抗形式的4个三维有限元模型,模型Ⅰ以上颌第二前磨牙和第一磨牙为支抗;模型Ⅱ以上颌第二前磨牙、第一、二磨牙共同作为支抗;模型Ⅲ以通过横腭杆连接的两侧上颌第一磨牙作为支抗;模型Ⅳ以植入上颌第一、二磨牙牙槽间隔颊侧的微螺钉种植体作为支抗。通过分析4种不同支抗形式在受到1N近中向力后上颌第一磨牙牙周膜的Von mises应力,来比较4种不同支抗形式对控制上颌第一磨牙近中移动的效果。结果模型Ⅰ中上颌第一磨牙最大应力为6.29×10-2Mpa;模型Ⅱ中上颌第一磨牙最大应力为3.11×10-4Mpa,应力较模型Ⅰ较少了99.5%;模型Ⅲ中上颌第一磨牙最大应力为5.93×10-2Mpa,应力较模型Ⅰ仅减少了5.7%;模型Ⅳ中上颌第一磨牙最大应力为4.99×10-4Mpa,应力较模型Ⅰ减少了99.2%。结论把第二磨牙纳入支抗系统或使用微螺钉种植体都可以显著减少第一磨牙的近中移动,而横腭杆对抑制第一磨牙的近中移动基本没有作用。

Objective To investigate the effect of different anchorages on stress distribution in periodontal ligament of upper first molar using a three-dimensional finite element method.Methods Four finite element models with different anchorage were created in this study.The anchorage of the model 1 consisted of maxillary second premolar and first molar;in model 2 the upper second molar was added to the anchorage;model 3 was based on model 2,in which two sides of the first molars were connected with a transpalatal arch.In model 4 a miniscrew was inserted buccally into the alveolar bone between the upper first and second molar.A 1N distal mesial force was applied at anchorage in each model to simulate tooth mesial movement.A linear finite element analysis was used to analyze the biomechanical effects of different anchorages on mesial movement of upper first molar.Results The maximum Von mises stress in periodontal ligament of upper first molar was 6.29×10-2,11×10-4,5.93×10-2 and 4.99×10-4MPa in models 1,2,3 and 4,respectively;comparing to model 1 the maximum Von mises stress was decreased by 99.5%,5.7% and 99.2% in model 2,3 and 4,respectively.Conclusion Adding second molar to the anchorage system and using miniscrew implant can effectively prevent first molar from mesially moving;however,the transpalatal arch has little effect.