Background and Aims: The All-on-4 design with its significant advantages is an appropriate model in reconstruction of edentulous mandible. Evaluation of stress and strain distribution in this model is necessary for better judgment. The purpose of this FEA study was to measure stress and strain distribution on peri-implant bone in All-on-4 design in edentulous mandible.

Materials and Methods: Three dimensional finite element model of human mandible was simulated according to data from CT-Scan of a cadaver. The model of 4×13.5 mm Nobel Biocare implant was simulated. Posterior implants were inserted in 452 inclination and anterior implants were parallel and vertical. Implants were splinted with a titanium bar and an acrylic superstructure was then simulated around the bar. Vertical loads of 178 N and 300 N were applied at incisor and left first molar positions, respectively. After meshing, defining boundary conditions and materials properties, analysis was performed with the aid of ABAQUS.

Results: Maximum Von-Mises stress of 38.9 MPa during anterior loading was located in peri-implant bone of anterior implants but maximum strain was observed in peri-implant bone of posterior implants. In posterior loading, maximum stress (77.3 MPa) was in peri-implant bone of posterior implant which was next to the place of load insertion. Maximum strain was found in the same area.

Conclusion: During posterior loading, significant amount of strain was observed in peri-implant bone of posterior angulated implant. As a result, there was a possibility of resorption in this area. During anterior loading, detected stress and strain was absolutely favorable.