主桩辅桩联合修复对前磨牙应力的有限元分析

Three-dimensional finite element analysis of premolars restored with master fiber post-combined with auxiliary fiber post

目的研究下颌第一前磨牙仅用纤维桩主桩和主桩与辅桩联合应用时,牙体及修复体所受应力大小分布的影响。方法选择19颗正常的离体下颌第一前磨牙,应用锥形束CT(CBCT)扫描,获取图像,选取扁形单根管前磨牙1颗,经根管治疗及桩道预备此牙后,再次以相同条件进行CBCT扫描,利用三维有限元法建立只应用主桩的分析模型A及主桩与辅桩联合应用的模型B,分析不同载荷情况下牙体和修复体上的应力大小及分布情况。结果当受到与牙体长轴成相同角度的载荷时,模型A和模型B的牙体组织和桩上的应力大小及分布无明显差异。同等大小的载荷,随着加载角度增大,模型A和模型B牙体组织上应力均明显增大。结论辅桩对修复体应力的影响不大,但随着加载角度的增大,修复体上应力明显增大。

Objective This study aims to compare stresses of the mandibular first premolar restored with master fiber post only or combined with auxiliary fiber post. Methods A total of 19 normal mandibular first premolars were selected and scanned by cone-beam computed tomography（CBCT）. Premolars with flat root canal were selected and treated using standard randomized controlled trial procedures and post-space preparation. Then, a repeat CBCT scan was conducted on the prepared tooth. Three-dimensional models were established according to results of CBCT scan. The model using the master fiber post only was named A, and another model that used master fiber post in combination with auxiliary post was labeled B. Two models were loaded in three different directions, and corresponding stress distributions were analyzed. Results After comparing A and B, results showed that stress distribution between tooth tissue and fiber post features no significant difference with loading force angle and long axis of tooth. Peak value of von Mises stress in models A and B increased significantly as loading angle increased. Conclusion Auxiliary fiber post poses minimal influence on premolar restoration after exposure to stress. However, this influence intensifies on loading angles.