Effects of bone types on bone remodeling of a single implant: a Finite Element study

Abstract

Objective: This study investigated the responses of bone remodeling process with respect to the effect of different bone type and occlusal loading location by analyzing stress, strain, strain energy density, and density distribution in a mandibular bone of implant supported single crown. Materials and methods: Standard implant in diameter of 4.2 mm and length of 10 mm in five types of bone (D1, D2, D3, D4, and grafted bone) with different occlusal loadings including non-occlusal contact (area loaded) and occlusal contact (center and 2-mm offsets horizontally loaded) were used to explore the stresses and strains transferred from the ceramic crown to the peri-implant bone through the implant. The implant was drawn and traced to simulate the model for finite element analysis (FEA). An artificial mandibular bone was constructed and assembled with an implant model. A 200 N loading was applied at the center of the crown and a strain energy density (SED) was used to stimulate cortical and cancellous bone remodeling over the first 12 months after implant placement. Results: Different occlusal loading location had a significant effect on bone remodeling responses in aspect of the stress/strain distribution and average peri-implant bone density. Every bone types under 2-mm offsets loading presented the highest stresses, strain, strain energy density, and bone density compared with other occlusal loading locations. Under 2-mm offsets loading, the greatest remodeling rate was achieved in D3 and D4 bone with slightly different values, an average peri-implant bone density in cortical bone were 1.95 and 1.77 g/cm3 and in cancellous bone were 1.08 and 1.06 g/cm3 , respectively, followed by D2, grafted bone, and D1 bone type after 12 months of bone remodeling. The remodeling rate was rapidly high in the first to second month of loading and continuously decreased until 12 months. Conclusion: Within the limitations of this study, the occlusal loading location appeared to be an important role than the bone type. An increased occlusal loading offset affected faster remodeling activities. D3 and D4 bone had the fastest remodeling process when compare with other bone types, resulting in more bone density and strength in a first few months of implant healing time process. However, D3 and D4 bone types with greater off-axial loading also had the greatest stress and strain at bone-implant interface that may interrupt primary implant stability during osseointegration process. In the grafted model, stress and strain are mostly deposited in grafted area, resulting in decreased remodeling rate in cortical and cancellous region.