The Effect of Preparation Design on Stress Distribution in Lithium Disilicate Laminate Veneer using 3D Finite Element Analysis.

Abstract

Background: A layer of ceramic bonded to the facial surfaces of prepared teeth to create a ceramic esthetic veneer, also known as a laminate veneer. Objective: This study aimed to examine the effect of preparation design on the stress distribution in lithium disilicate veneer at different angulations of masticatory loading. Methods: The finite element approach assessed the structure stress distribution. So, Exocad dental CAD was used to obtain the models, which consist of an upper central incisor in three dimensions (3D), and prepare them with the same software for an indirect veneer. The models were imported into software (SolidWorks; Dassault Systems) to construct solid models. The external load used in this study was 100 N at 60 degrees (intercuspal) and 125 degrees (protrusive) in the palatal surface, two mm below the incisal edge. The models were restored using e-max laminate veneers with different tooth preparation designs (palatal chamfer and window preparation designs). Analysis and calculations were performed on the stress distributions and maximum stress values of the tooth structures, cement layer, and laminate veneer. Results: With a window preparation design, the maximum stress values in the tooth and laminate veneer were higher. In the palatal chamfer design, stresses were dispersed more consistently through the cement layer and laminate veneer. Higher stress was generated by protrusive movement than by intercuspal movement. Conclusion: Compared to window preparation, the palatal chamfer design for lithium disilicate laminate veneer showed a more favourable stress distribution. Regardless of the preparation design, maximum stress values were observed in the cervical and incisor areas of the tooth structure.