Micromechanical Analysis and Crack Propagation Simulation of Enamel/Ceramic Adhesive Interface in an Incisor Veneer Using Three-Dimensional Finite Element Submodeling and Element Deactivation Approaches

Abstract

Retention of veneering materials to the tooth influences the survival rate in which depends primarily on an adequate adhesive bonded to enamel and ceramic substrates. Microleakages associated with resin monomers penetrating in enamel–etched porosities arise as the key issue to cause crack propagation and induce de-bonding in adhesive layer. The aim of this study is to investigate the micromechanical responses and crack propagation in a ceramic veneer adjacent to an incisal-overlapped incisor using the finite element (FE) submodeling and the element deactivation techniques. Section contours of an intact maxillary central incisor were acquired from microcomputed tomography (CT) to construct a three-dimensional (3D) FE macromodel considered with butt joint veneer design using mapping mesh approach. Ten loads from 10 to 100 N increments with 10 N were applied with an angulation of 60° to the tooth longitudinal axis at the incisal edge in the macromodel as the loading conditions to perform the simulations. The micromodel was constructed at an enamel–adhesive interface, where was the stress concentration area in the macromodel. The morphology and dimensions of the resin tags at the interface were assigned based on a SEM micrograph. Boundary conditions of the micromodel were determined from the macromodel results. An iterative code with the element deactivation technique was used while the local element stresses exceeding a self-testing tensile strength in adhesive layer to simulate the microcrack propagation. Stress concentration within the adhesive occurred at the enamel–adhesive interface of the lingual edge from the macromodels findings and at their resin tags base from the micromodels results. The maximum stress value in the micromodel exceeded the tensile strength (11.8 MPa) of resin cement when loading condition was 50 N. A simulated fracture path was found at the resin tags base along the enamel–adhesive interface from lingual to labial side. This study indicated that the FE submodeling and the element deactivation techniques could simulate efficiently the micromechanical responses and the microcrack propagation noted at the enamel–adhesive interface in the veneer system.