Zhongjie Li1, Zheng Yang2, Ling Zuo3, Yukun Meng4. 1. Postgraduate student, Department of Prosthodontics, West China School of Stomatology, Sichuan University, Chengdu, Sichuan, China. 2. Associate Professor, Department of Temporomandibular Joint, West China School of Stomatology, Sichuan University, Chengdu, Sichuan, China. 3. Graduate student, Department of Prosthodontics, West China School of Stomatology, Sichuan University, Chengdu, Sichuan, China. 4. Associate Professor, Department of Prosthodontics, West China School of Stomatology, Sichuan University, Chengdu, Sichuan, China. Electronic address: yukunmeng@hotmail.com.
Abstract
STATEMENT OF PROBLEM: Mechanical properties are important in the long-term success of restorations, but whether different incisal preparations can affect the behavior of veneers remains controversial. PURPOSE: The purpose of this study was to evaluate the influence of different preparation designs on stress distribution in a maxillary incisor restored with veneers and with regard to different restorative materials and loading conditions. MATERIAL AND METHODS: Based on the cone beam computed tomography scanning of a maxillary incisor, 3-dimensional finite element models for 2 different designs were developed. A static load of 50 N was applied with angulations of 60 degrees and 125 degrees to the longitudinal axis at the level of the incisal margin, simulating functional movements. Both porcelain laminate veneer and composite resin veneer were considered. The maximum stress values and stress distribution of the veneer, cement layer, and tooth structure were calculated and analyzed. RESULTS: The maximum stress values in the veneer and tooth were higher with the butt-joint design. Stresses were distributed more uniformly in the cement layer in the palatal chamfer design for porcelain laminate veneers, whereas a better stress distribution under protrusive movement was observed in the butt-joint design for composite resin veneers. CONCLUSIONS: The palatal chamfer design for porcelain laminate veneers tolerated stress better, whereas the butt-joint design was favored for composite resin veneers, particularly under protrusive movement.
STATEMENT OF PROBLEM: Mechanical properties are important in the long-term success of restorations, but whether different incisal preparations can affect the behavior of veneers remains controversial. PURPOSE: The purpose of this study was to evaluate the influence of different preparation designs on stress distribution in a maxillary incisor restored with veneers and with regard to different restorative materials and loading conditions. MATERIAL AND METHODS: Based on the cone beam computed tomography scanning of a maxillary incisor, 3-dimensional finite element models for 2 different designs were developed. A static load of 50 N was applied with angulations of 60 degrees and 125 degrees to the longitudinal axis at the level of the incisal margin, simulating functional movements. Both porcelain laminate veneer and composite resin veneer were considered. The maximum stress values and stress distribution of the veneer, cement layer, and tooth structure were calculated and analyzed. RESULTS: The maximum stress values in the veneer and tooth were higher with the butt-joint design. Stresses were distributed more uniformly in the cement layer in the palatal chamfer design for porcelain laminate veneers, whereas a better stress distribution under protrusive movement was observed in the butt-joint design for composite resin veneers. CONCLUSIONS: The palatal chamfer design for porcelain laminate veneers tolerated stress better, whereas the butt-joint design was favored for composite resin veneers, particularly under protrusive movement.