Biomechanical evaluation of conventional, zygomatic, zygomatic bone anchored subperiosteal and maxilla anchored subperiosteal implants applied totally edentulous maxilla: finite element stress analysis

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BACKGROUND: This study aims to evaluate the stress distribution under occlusal forces by using finite element analysis (FEA) to compare conventional, zygomatic, and differently designed subperiosteal implants (SI) in edentulous atrophic maxilla. METHODS: A 3D model of an edentulous atrophic maxilla was reconstructed from CT scans. Three models were simulated: Model 1 with zygoma and conventional implants, Model 2 with apertura piriformis and subperiosteal implants extending to the zygomaticomaxillary buttress, and Model 3 with apertura piriformis and subperiosteal implants covering the zygomatic buttress. Mechanical properties were assigned according to the literature; 150 Newton (N) force per tooth was applied for occlusal loading, and 100 N force was applied for oblique loading. RESULTS: When the highest tensile (Pmax) and compressive (Pmin) stresses in the bone under vertical and oblique forces were examined, the highest stress was observed in Model 1, and the lowest was observed in Model 3. The von Mises stress values observed in the metal substructure were the highest in Model 1 and the lowest in Model 3. The von Mises stress in the abutments and implants was highest in Model 3 and lowest in Model 1. When the subperiosteal implant screws were examined, more von Mises stress was observed in the subperiosteal implant screws used in Model 3 than in those used in Model 2. Among the three different treatment options applied in the atrophic maxilla, the highest stress in the bone occurred in the conventional and zygomatic implants, and the lowest stress occurred in the subperiosteal implant with a zygomatic bone anchor. CONCLUSIONS: Different types and designs of implants may be alternatives to advanced surgical methods in the rehabilitation of atrophic maxillary lesions. This study underscores the importance of implant and bone design in choosing optimal anchorage zones, particularly in cases of severe bone loss in the edentulous maxilla. In light of these findings, we recommend implant systems that are specially developed for appropriate rehabilitation in the atrophic edentulous maxilla.