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目的:研究下颌第一磨牙分根后2种修复方式对磨牙应力分布的影响。方法 :利用锥形束CT(CBCT)扫描和Mimics、Geomagic、UG处理图像,建立下颌第一磨牙分根术后单冠和联冠修复的三维有限元模型。分别进行垂直和斜向加载,计算正常下颌第一磨牙及2种修复方式下牙体和牙周组织的应力。结果:垂直载荷时,2种修复模型与正常磨牙牙体、牙周应力分布相似;牙体应力极值和牙周膜最大主应力值均增加,单冠模型增幅较大。斜向载荷时,联冠模型与正常磨牙牙体、牙周应力分布相似,单冠模型远中根及牙周膜颊侧根下半部应力集中区增大;牙体应力极值和牙周膜最大主应力值均增加,单冠模型增幅较大。结论:下颌第一磨牙分根术后选择联冠修复更为合理。
Objective: To study the effects of two kinds of repair methods on the stress distribution in the molar after root-cutting of the first molar. Methods: CBCT and Mimics, Geomagic and UG images were used to establish the three-dimensional finite element model of single crown and conjoined crown after root canal cutting. Vertically and obliquely loaded, respectively, to calculate the normal mandibular first molar and two kinds of repair methods of tooth and periodontal tissue stress. Results: At the vertical load, the periodontal stress distribution of the two kinds of restoration model was similar to that of the normal molar. The maximal stress value of the tooth body and the maximal principal stress of the periodontal ligament increased, and the amplitude of the single crown model increased significantly. In diagonal loading, the stress distribution of periodontal ligament in the model of conjoined crowns was similar to that of normal teeth, and the concentration of stress concentration in the distal root of the single crown model and the buccal root of the periodontal ligament increased. The main stress values are increased, a single crown model a larger increase. Conclusion: It is more reasonable to select the crown after the first molar of the mandibular first root canal repair.