Monteiro Jaiane Bandoli, Dal Piva Amanda Maria de Oliveira, Tribst João Paulo Mendes, Borges Alexandre Luiz Souto, Tango Rubens Nisie
Department of Dental Materials and Prosthodontics, São Paulo State University (Unesp), Institute of Science and Technology, São José dos Campos, SP, Brazil.
Iran Endod J. 2018 Spring;13(2):188-194. doi: 10.22037/iej.v13i2.19089.
This study aimed to investigate the influence of the resection angle on the stress distribution of retrograde endodontic treated maxillary incisors under oblique-load application.
A maxillary central incisor which was endodontically treated and restored with a fiber glass post was obtained in a 3-dimensional numerical model and distributed into three groups according to type of resection: control; restored with fiber post without retrograde obturation, R45 and R90 with 45º and 90º resection from tooth axial axis, respectively and restored with Fuji II LC (GC America). The numerical models received a 45 occlusal load of 200 N/cm on the middle of lingual surface. All materials and structures were considered linear elastic, homogeneous and isotropic. Numerical models were plotted and meshed with isoparametric elements, and the results were analyzed using maximum principal stress (MPS).
MPS showed greater stress values in the bone tissue for control group than the other groups. Groups with apicectomy showed acceptable stress distribution on the fiber post, cement layer and root dentin, presenting more improved values than control group.
Apicectomy at 90 promotes more homogeneity on stress distribution on the fiber post, cement layer and root dentin, which suggests less probability of failure. However, due to its facility and stress distribution also being better than control group, apicectomy at 45 could be a good choice for clinicians.
本研究旨在探讨在斜向加载情况下，切除角度对上颌切牙逆行根管治疗后应力分布的影响。
在三维数值模型中获取一颗经根管治疗并用玻璃纤维桩修复的上颌中切牙，并根据切除类型分为三组：对照组；用纤维桩修复但未进行逆行充填；R45组和R90组，分别从牙轴方向以45°和90°进行切除，并用富士II LC（美国GC公司）修复。数值模型在舌面中部承受200 N/cm的45°咬合负荷。所有材料和结构均视为线弹性、均质和各向同性。对数值模型进行绘制并用等参单元划分网格，结果采用最大主应力（MPS）进行分析。
MPS显示对照组骨组织中的应力值高于其他组。进行根尖切除术的组在纤维桩、粘结层和牙根牙本质上显示出可接受的应力分布，其值比对照组有更大改善。
90°根尖切除术能使纤维桩、粘结层和牙根牙本质上的应力分布更均匀，这表明失败的可能性较小。然而，由于其操作简便且应力分布也优于对照组，45°根尖切除术可能是临床医生的一个不错选择。
