A 3D-FEA study on the impact of different preparation forms and materials on posterior occlusal veneers

Abstract

ObjectivesTo study the stress distribution and bonding performance in posterior occlusal veneers and tooth bodies under different preparation forms and materials. MethodsAn isolated lower right first molar was prepared with non-retention type (type A), cavity-retained type (type B), and encircling-retention type (type C) forms. MicroCT images of the tooth were obtained and digitally converted into three-dimensional solid models. Three-dimensional models of veneers for the three abutment teeth were designed, fabricated, and divided into nine models (AEM, ALU, AVE, BEM, BLU, BVE, CEM, CLU, and CVE) according to the material used (E.max CAD [EM], Lava Ultimate [LU] and Vita Enamic [VE]). Three-dimensional finite element stress analysis was performed by applying vertical and oblique forces (200 N) to simulate chewing loads using ABAQUS. Finally, an adhesive stiffness degradation diagram was obtained using the rotatory dislocation simulation method. ResultsThe BEM model had the largest equivalent stress extreme value (160.50 MP A) when a vertical load was applied to the veneers, while there was no significant difference when it was applied to dental tissues. The equivalent stress extreme values of each part under an oblique load were significantly greater than those under a vertical load. The AEM model had the largest values when the loads were applied to the veneers (350.60 MP A) and the dental tissues (40.13 MP A). The equivalent stress extreme values of the veneers were ranked as LU < VE < EM for different materials, and LU > VE > EM for dental tissues. Bonding performance results were C > B ≈ A and LU > VE > EM. ConclusionsThe cavity-retained type better protected the veneers and dental tissues than the non-retention and encircling-retention types under lateral forces. E.max CAD material, with a high elastic modulus, reduced the stress transmitted to the remaining dental tissues. Lava Ultimate exhibited the best bonding performance.