Biomechanical assessment of axial and inclined design with different implant positions in full-arch implant restoration

Multiple implants need to be placed in different regions of the mandible based on the remaining bone mass assessment and implantation procedure of different patients with complete edentulousness. However, little is known about the impact of the implant sites arrangement on framework, distal implant and surrounding bone stress. This paper was to explore the biomechanical behavior changes of the implant sites distribution on the framework in the axial design and compared with the inclined design. Arched mandible models with four different implant placement arrangements were built using 4 axial implants. Another alternative inclined design was generated for comparison with the axial design while maintaining an even distribution of the implant positions. A 300 N oblique load at 45° to the occlusal plane was applied to bilateral posterior-tooth area for finite element analysis. For the axial design, the maximum stress occurred in groups with multiple implants adjacently arranged, whereas the minimum peak stress occurred in groups with each implant evenly spaced. The inclined group exhibited lower stress levels on the distal implant and surrounding bone. For full-arch implant restorations, an inclined designed with 4 implants evenly distributed on the mandible is preferred to obtain optimal stress distribution.