下颌切牙的窝洞设计方案：有限元研究的机械方面。

Options for Access Cavity Designs of Mandibular Incisors: Mechanical Aspects from Finite Element Study.

机构信息

Department of Endodontics, Faculty of Dentistry, The British University in Egypt, El Sherouk City, Egypt.

Department of Endodontics, Faculty of Dentistry, The British University in Egypt, El Sherouk City, Egypt; Center for Innovative Dental Sciences, Faculty of Dentistry, The British University in Egypt, El Sherouk City, Egypt; Department of Endodontics, Ain Shams University, Cairo, Egypt.

出版信息

J Endod. 2023 Dec;49(12):1706-1712. doi: 10.1016/j.joen.2023.09.012. Epub 2023 Oct 4.

DOI:10.1016/j.joen.2023.09.012

PMID:37802135

Abstract

INTRODUCTION

This study investigated different access cavity designs of mandibular anteriors in terms of their effect on the biomechanical behavior and longevity using finite element analysis (FEA).

METHODS

A 3-dimensional model of a mandibular incisor was created for FEA. After validating the intact tooth (IT) model, 4 experimental models were developed (traditional lingual access cavity [TLA], facial access cavity [FAC], incisal access cavity [ICA], and cervical access cavity [CVA]). Cyclic loading was simulated, and the number of cycles until failure (NCF) was compared to the IT model. Stress distribution patterns, maximum von Mises stresses (vMSs), and maximum principal stresses (MPSs) were analyzed mathematically. The safety factor was also calculated and demonstrated.

RESULTS

The maximum vMS registered on the IT model was 134.16 MPa. The FCA and the CVA provided the highest NCF (193.7% compared with the IT model) followed by ICA (58.2%) and TLA (21.4%). The vM and MPS analysis revealed that the lingual surface is a primary stress channel, and the presence of an access cavity significantly weakens the tooth structure. Although the maximum vMS registered for the IT model was 134.16 MPa, the maximum vMS was 73.97 MPa for both the FCA and the CVA, 152.27 MPa for the ICA, and 173.63 MPa for the TLA.

CONCLUSIONS

The facial and cervical access cavity designs provided considerable reinforcement to the endodontically treated mandibular incisors. With advancements in esthetic restorative materials and endodontic instruments, facial access design could emerge as the new standard for access cavity preparation in mandibular incisors.

摘要

引言

本研究通过有限元分析（FEA）研究了下颌前牙不同的入口洞型设计对生物力学行为和耐久性的影响。

方法

创建了下颌切牙的三维模型进行 FEA。在验证完整牙齿（IT）模型后，开发了 4 个实验模型（传统舌侧入口洞型[TLA]、颊侧入口洞型[FAC]、切缘入口洞型[ICA]和颈缘入口洞型[CVA]）。模拟循环加载，并将失效前的循环次数（NCF）与 IT 模型进行比较。通过数学分析分析了应力分布模式、最大 von Mises 应力（vMS）和最大主应力（MPS）。还计算并展示了安全系数。

结果

IT 模型上记录的最大 vMS 为 134.16 MPa。FCA 和 CVA 提供了最高的 NCF（与 IT 模型相比提高了 193.7%），其次是 ICA（提高了 58.2%）和 TLA（提高了 21.4%）。vM 和 MPS 分析表明，舌侧表面是主要的应力通道，入口洞的存在显著削弱了牙齿结构。尽管 IT 模型上记录的最大 vMS 为 134.16 MPa，但 FCA 和 CVA 的最大 vMS 均为 73.97 MPa，ICA 为 152.27 MPa，TLA 为 173.63 MPa。