The treatment of severely atrophic posterior maxillae without bone augmentation by using zygomatic implants has received a major attention in prosthodontics due to great implant survival rates. However, mechanical implant system failures were still reported irrespective of surgical techniques used for zygomatic implant placement. Two main prominent approaches, the intrasinus and extramaxillary possess their own advantages and drawbacks with no particular indication found, to date, to highlight the best technique in relation to prosthesis stress. Thus, this study emphasised on the computational evaluation of both approaches with regards to the prosthesis responses. Two sets of finite element models comprising bones, soft tissue, implants, abutments, and prosthesis were prepared accordingly. The models were then assigned with the material properties, contact modelling, and loadings as closely as possible with the real conditions. The results showed that the extramaxillary technique reported a more promising maximum stress value and distribution within the prosthesis than the intrasinus. Moreover, the prostheses in both approaches seemed to have a low tendency to failure as the stress levels were significantly less than the stress limit of the material.
