Influence of diameter and intraradicular post in the stress distribution. Finite element analysis

Abstract Introduction The biomechanical behavior of endodontically treated teeth depending on the selected restorative material and tooth situation to be restored. Objective To analyze by the two-dimensional finite element method the biomechanical behavior of different diameters in intraradicular posts and teeth with coronal remaining of 2mm. Material and method Six models were made with three types of posts, as follows: Glass fiber post, carbon fiber post, and cast metal post, both with diameter # 1 (1.1 mm in diameter) and # 2 (1.3 mm of diameter). The modeling was performed using the Rhinoceros 4.0 program. The FEMAP 10.2 and NEiNastran 9.2 programs were used to develop finite element models. The loading used was 100N for axial and oblique forces. The results were visualized using the von Mises stress map. The statistical analysis was made using analysis of variance (ANOVA) and Tukey post-test, with a significance level of 5%. Result The oblique loading stress values were higher than the axial loading (p<0.001) for both situations. The glass fiber post showed the lowest concentrations of stress on both loads (p<0.001). The carbon fiber post presented significant difference compared to the cast metal post, only in the oblique load (p=0.007). The diameter did not increase the stress of the evaluated posts (p=0.302). Conclusion The fiber posts were more favorable for restoration of endodontically treated teeth; the increase of diameter did not influence the increase of tension; the oblique load was more harmful for both posts and tooth structure.

摘要 引言
牙髓治疗后牙齿的生物力学行为取决于所选修复材料与待修复牙齿的具体状态。

目的 采用二维有限元法（two-dimensional finite element method），分析不同直径根管内桩（intraradicular posts）以及牙冠剩余组织厚度为2mm的牙齿的生物力学行为。

材料与方法 本研究共构建6组模型，涵盖3类根管桩：玻璃纤维桩、碳纤维桩及铸造金属桩，每类桩分别设置直径#1（直径1.1mm）与#2（直径1.3mm）两种规格。建模采用Rhinoceros 4.0软件，有限元模型的构建依托FEMAP 10.2与NEiNastran 9.2软件完成。轴向与斜向载荷均设置为100N，研究结果通过冯·米塞斯应力云图（von Mises stress map）进行可视化呈现。统计分析采用方差分析（ANOVA）与Tukey事后检验（Tukey post-test），设定显著性水平为5%。

结果 两种载荷条件下，斜向载荷的应力值均高于轴向载荷（p<0.001）。玻璃纤维桩在两种载荷下的应力集中程度均为最低（p<0.001）。仅在斜向载荷条件下，碳纤维桩与铸造金属桩的应力水平存在显著性差异（p=0.007）。桩径增大并未提升受试根管桩的应力水平（p=0.302）。

结论 纤维桩更适用于牙髓治疗后牙齿的修复；桩径增大不会提升应力水平；斜向载荷对根管桩及牙齿结构的损伤更为显著。