The Post-core Crown Restored Anterior Teeth With Different Adhesives: Three-dimensional Finite Element Stress Analysis

Objective:To compare stress in the varying adhesives on the residual dentine and the adhesive layer in post-core crown restored anterior teeth, by means of three dimensional finite element analyses. To provide data for choosing clinical adhesive material, which has long service life of prosthetic replacement.Methods:The finite element model of the maxillary central incisor was set up using the Computed Tomographic (CT) scanning technology, MIMICS software and the ANSYS software. The model includes all-ceramic crowns, post-core, residual dentine, adhesive layer,periodontal membrane, alveolar bone, and gutta pertscha. Then the model was divided into experimental groups according to the adhesive material. The normal bite force of the maxillary central incisor was simulated to observe the peak value and distribution of the Von Mises stress and maximum principal stress (S1) on the residual dentine and adhesives layer.Results:1. Under the load, the stress in residual dentine was shown to be decreasing with increasing elastic modulus of adhesive material, with 1%of the decreasing amplitude. According to distribution of the stress pattern, Von mises stress is located on the lip side of the 1/3 root and the maximal tensile stress on the lingual side of the 1/3 root.2. Under the load, the stress in adhesives layer was shown to be increasing with increasing elastic modulus of adhesive material, with 110%of the increasing amplitude. The stress in adhesives layer was shown to be increasing with increasing elastic modulus of post-core material, with 50%of the increasing amplitude. According to distribution of the stress pattern, the scope of high-stress area was increased with elastic modulus of adhesive material.Conclusion:1. There are no variations on the peak value and distribution of the stress on the residual dentine.2. The stress in adhesive layer increases with the elastic modulus of post and adhesive. It suggests that choosing lower elastic modulus of post and adhesive is able to protect bonding interface of post restoration.3. The lip and lingual side of the 1/3 root is the most likely site of root fracture. The clinical course of root canal preparation should be extended as far as possible in the near-and far, in order to retain morel lip and lingual tooth structure and to reduce the risk of occurrence of root fracture.4. When bonding of Ni-Cr alloy post, the adhesive with zinc phosphate should be minimal.