Influence of Cortical Layer Thickness of Alveolar Bone on Stress Distribution over Implant Supported Region

摘要

This study discusses the stresses in alveolar bones with various thicknesses of cortical layer around the implanted fixed partial denture subject to occlusion or external load. The stresses induced by occlusion and external loads can vary with the condition of the bone. For verification, a physical model with identical shape to the digital model and with similar material properties, loads, and boundary conditions was built. The data obtained from the physical model agreed well with that obtained from the simulations performed on the digital model. After the reliability of the finite element method (FEM) digital model had been confirmed, stresses induced by occlusion and external loads were studied. The induced stress level on the cortical bone increased with the decrease in the cortical layer. When the cortical layer vanished, the induced stress level significantly dropped. The soft cancellous bone supported the implanted complex completely once the cortical layer had gone. However, the induced displacement continued to increase more rapidly as the cortical layer thickened or vanished. A lateral load applied to the complex was also studied. The movement between the natural bone and the implant increased with the decrease in the cortical layer. This could lead to the stability problem of the implant denture and osseointegration. The results indicate that patients with thinner cortical bone carried a higher risk of failure during the restoration.