背景:这项体外研究的目的是比较和评估用核后冠修复的上颌第一前磨牙残余冠的应力分布,深缘抬高后的内冠和镶嵌冠,利用有限元分析探讨残冠的拟合恢复。
方法:通过锥形束计算机断层扫描(CBCT)扫描来自男性成年人的健康的完整右上颌第一前磨牙。利用Mimics等逆向工程软件建立了牙齿的有限元模型,Geomagic和Hypermesh。在此基础上,制作了深缘高程后的残冠模型,将实验组模型分为三组,那些用核心后冠修复的,内冠和镶嵌冠。对实验模型施加垂直和倾斜的静态载荷,以模拟咀嚼过程中牙齿上的力(加载位置位于枕骨表面的中央窝,并且负载为100N)使用Abaqus软件。
结果:观察了vonMises应力在实验模型各部分中的峰值和分布。深缘高程后,牙本质vonMises的峰值应力低于正常牙本质的抗拉强度,内生,和嵌体冠组;牙本质的后核心冠组应力结果最低,restoration,搪瓷,垂直和倾斜荷载下的深边高程(DME)层。就应力分布云而言,在两种载荷下,牙本质组织中的峰值应力都位于牙根的根尖1/3。而内冠和镶嵌冠修复后,颈部和根部区域的应力集中明显;无论负载和修复方法如何,相应的应力集中区域出现在DME和牙本质组织的交界处修复体的加载部位;结论:后核心冠,内冠和镶嵌冠可以用来恢复深缘抬高后的残余冠,核后冠可以更好地保护残牙组织。
BACKGROUND: The purpose of this in vitro study was to compare and evaluate the stress distribution of maxillary first premolar residual crowns restored with post-core crowns, endocrowns and inlay crowns after deep margin elevation, to explore the fitting restoration for residual crowns using finite element analysis.
METHODS: A healthy complete right maxillary first premolar from a male adult was scanned by cone beam computed tomography (CBCT). The finite element model of the tooth was established by reverse engineering software such as Mimics, Geomagic and Hypermesh. On this basis, the residual crown model after deep margin elevation was made, and the experimental group models were divided into three groups, those restored with post core crowns, endocrowns and inlay crowns. Vertical and oblique static loads were applied to the experimental models to simulate the force on the tooth during mastication (the loading position was located in the central fossa of the occipital surface, and the load was 100 N) using Abaqus software.
RESULTS: The peak value and distribution of von Mises stress in each part of the experimental model were observed. After deep margin elevation, the peak
dentin von Mises stresses were lower than the tensile strength of normal
dentin in the post-core crown, endocrown, and inlay crown groups; the lowest stress results were found in the post-core crown group for the
dentin, restoration, enamel, and deep margin elevation (DME) layers under vertical and oblique loading. In terms of stress distribution clouds, the peak stresses in the
dentin tissue were located in the apical 1/3 of the root after postcore crown restorations for both loads, while stress concentrations were evident in the cervical and root areas after endocrown and inlay crown restorations; regardless of the load and restoration method, the corresponding stress concentration areas appeared at the junction of the DME and
dentin tissue at the loading site of the restorations; CONCLUSIONS: Post-core crowns, endocrowns and inlay crowns can be used to restore residual crowns after deep margin elevation, and post-core crowns can better protect the residual tooth tissue.