Two-dimensional FEM analysis of hydroxyapatite implants: diameter effects on stress distribution

The effect of the diameter of hydroxyapatite (HAP) implants on stress distribution in alveolar bone was analyzed by two-dimensional finite element methods (FEM), with use of a 100-N vertical and lateral load. Since HAP is considered a bioactive material, the alveolar bone was assumed to be bonded directly to the HAP implant in the FEM model. The analysis showed that the stresses in cortical bone were generally higher than those in cancellous bone, and that the stress concentration occurred mainly in cortical bone around the neck of the implant with both vertical and lateral load. The stresses in cortical bone with lateral load were especially high-twice those in vertical load. Stresses in cortical bone decrease in inverse proportion to the increase in implant diameter with both vertical and lateral load. The results suggested that an implant with a large diameter is favorable from the standpoint of stress distribution.