The Effect of Offset Implant Configuration on Type IV Bone

Objectives: The aim of this study was to analyze stress distribution on cortical bone around hexagon external implants supporting three-element prostheses, varying the splinting and arrangement of the implants by 3D finite element analysis.
Methods: Three 3D models were modeled by using of InVesalius, SolidWorks and Rhinoceros software. Each model simulated a bone block (type IV) of posterior maxillary segment, varying the splinting and arrangement of the external hexagon implants (ø3.75 x 10 mm): (A) straight-line implants supporting single crowns, (B) straight-line implants supporting 3-unit splinted prostheses, (C) offset implant configuration supporting 3-unit splinted prostheses. The applied forces were 400N vertical and 200N oblique. The FEMAP software was used to construct the 3D finite element models in pre- and post- processing stages. The NEi Nastran software was used to analyze the finite element models. The stress on cortical bone was plotted by maximum principal stress (σmax) and microstrain (µstrain) criteria.
Results: Under axial and oblique loadings, the model C showed better stress distribution on cortical bone around implants compared to A and B models by σmax criteria. Furthermore, Model C showed better behavior biomechanical by µstrain criteria, in which showed the lowest values of µstrain on cortical bone.
Conclusions: Based on the methodology used, the offset implant configuration seems to be more effective to dissipate transmitted occlusal stress to cortical bone.