Department of Prosthodontics, School of Stomatology, Guizhou Medical University, Affiliated Stomatology Hospital of Guizhou Medical University, Guiyang, Guizhou Province, 550004, China.
Operative Dentistry and Endodontics, Guiyang Stomatological Hospital, Guiyang, Guizhou Province, 550002, China.
BMC Oral Health. 2024 Nov 6;24(1):1349. doi: 10.1186/s12903-024-05121-9.
There are differences in the research results regarding which edge design of occlusal veneers can achieve the best long-term success rate as a relatively new fixed prosthesis restoration method. Further research is needed. The three-dimensional finite element method was used to conduct stress analysis on occlusal veneers of maxillary first permanent molars with different thicknesses and margin preparation designs. The aim of this study was to provide mechanical research evidence and a reference for exploring standardized clinical protocols for the design of occlusal veneer restorations of maxillary first molars.
A 3Shape (Intraoral Scanner) was used to scan the maxillary first molar teeth in vitro, after which 3D printing was carried out. Three different edge designs were applied to identical teeth: straight-beveled finishing line(SFL), chamfer finishing line(CFL), and standard cuspal inclination(SCI). Preparation was carried out with a thickness of 0.5 mm. Using the surface deformation feature, the occlusal veneer was thickened to 0.5 mm and 1.0 mm, and periodontal ligaments were added. They were then placed into the upper and lower jaws and dental arches. Finite element analysis was performed after applying bite force dispersion to the loading area on the mandible following dynamic contact.
(1) As the thickness increased, the maximum Von Mises stress in the occlusal veneers SFL and CFL also increased, while the SCI exhibited the opposite trend. (2). The trend of the maximum Von Mises stress in the adhesive layer decrease gradually with increasing thickness of the occlusal veneer. The stresses of the SFL and CFL is concentrated primarily at the edge position below the functional cusp, resulting in relatively low adhesive stress. However, in the SCI group, the maximum stress at the edge of the adhesive layer exceeds the maximum shear strength of commonly used adhesives.
Under the experimental conditions, the mechanical properties of the maximum Von Mises stress in the SFL, CFL, and SCI occlusal veneers meet clinical needs. Incorporating the minimally invasive concept of tooth preservation, a thickness of 1.0 mm are optimal for glass ceramic occlusal veneers on maxillary first molars.
作为一种相对较新的固定修复体方法，牙体预备边缘设计对牙体预备后贴面的长期成功率影响存在差异，需要进一步研究。本研究采用三维有限元方法对不同厚度和边缘预备设计的上颌第一磨牙牙体预备后贴面进行应力分析，旨在为上颌第一磨牙牙体预备后贴面修复的标准化临床方案设计提供力学研究依据。
体外扫描上颌第一磨牙，3D 打印，在同一牙体上预备三种不同边缘设计：直边肩台（SFL）、斜面肩台（CFL）、标准牙尖斜度（SCI），厚度均为 0.5mm，通过表面变形特征将贴面增厚至 0.5mm 和 1.0mm，并添加牙周膜，将其置于上下颌和牙弓中，在加载区域进行动态接触后，对下颌进行分散咬合力的有限元分析。
（1）随着厚度的增加，SFL 和 CFL 贴面的最大 Von Mises 应力也随之增加，而 SCI 则呈现相反的趋势。（2）随着贴面厚度的增加，粘结层的最大 Von Mises 应力逐渐减小，SFL 和 CFL 的应力主要集中在功能尖下的边缘位置，导致粘结应力相对较低。然而，在 SCI 组中，粘结层边缘的最大应力超过了常用粘结剂的最大剪切强度。
在实验条件下，SFL、CFL 和 SCI 贴面的最大 Von Mises 应力的力学性能满足临床需求。在保留牙齿微创理念的基础上，上颌第一磨牙玻璃陶瓷贴面的最佳厚度为 1.0mm。
