Micro-mechanical analysis and crack propagation simulation of an enamel-ceramic interface

Objectives: This study utilized finite element (FE) submodeling and element birth and death technologies to investigate the micro-mechanical behaviors and micro-failure accumulation at the enamel-adhesive interface. Methods: A plane strain FE macro-model of the enamel-adhesive-ceramic complex was generated. A 10 N vertical load was applied to the ceramic to perform shear bond test. The stress concentration area found in the macro-model was selected to construct a micro-model which included the resin tags morphology based on SEM micrograph to execute the submodeling simulation. The principal stress on each node in the micro-model was calculated to investigate the interfacial micro-mechanics according to the cut boundary conditions in the macro-model. Element birth and death technology provided in the FE method was adopted to simulate the resin tags failure accumulation in the micro-model. A parallel in-vitro shear test experiment (n = 10) was also performed to validate the simulation. Results: The macro-model solutions revealed that the maximum principal stress (17.21 MPa) of the adhesive layer was found at the upper enamel-adhesive region. The micro-model results demonstrated that the stress concentration occurred at the upper corner near the enamel-adhesive region (30.02 MPa) and the base of the resin tags (25.14 MPa). The simulation fracture path initiated at the upper corner and then propagated at the resin tags base along the interface. The SEM morphological fracture patterns obtained from in-vitro shear testing corresponded and validated the simulation results. Conclusions: The FE submodeling and element birth and death technologies could better simulate the interfacial micro-mechanical responses and micro-failure accumulation noted at the enamel-adhesive interface.