Biomechanical evaluation of prosthetic framework materials in subperiosteal implants: a finite element analysis

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BACKGROUND: This finite element analysis was performed to evaluate the stress distribution and biomechanical performance of various prosthetic framework materials supported by subperiosteal implants. This study aimed to evaluate the biomechanical behavior of framework materials with different elastic modulus using finite element stress analysis. METHODS: A three-dimensional finite element model of a completely edentulous maxilla was reconstructed using computed tomography data of a patient. A subperiosteal implant was designed with four different framework materials: cobalt-chrome (CoCr), titanium (Ti), zirconia (Zr), and polyetheretherketone (PEEK). To generate five distinct prosthetic designs, the Ti framework was veneered with both porcelain and acrylic resin, while CoCr and Zr were veneered with porcelain, and PEEK was veneered with composite resin. A vertical force of 100 N at an anterior region, 150 N of vertical forces and 100 N oblique forces at posterior region was applied simultaneously. Principal stress in bone, von Mises stress in implants, prosthetic frameworks, implant screws, and prosthetic screws were calculated and compared. RESULTS: The PEEK-composite framework exhibited the highest stress values in bone, implants, and screws, while the CoCr framework demonstrated the lowest. Compared to CoCr, the PEEK-composite combination produced approximately 14% higher cortical bone stress, 22% higher trabecular bone stress, and nearly 96% higher prosthetic screw stress. Titanium-acrylic and titanium-porcelain combinations showed similar stress distributions, indicating that the elastic modulus of the veneering material had no significant influence. Among all components, the prosthetic screw exhibited the greatest stress concentration (233 MPa), whereas fixation screws showed lower stress levels, with a maximum of 71 MPa. CONCLUSIONS: The success of implant supported prostheses may be influenced by the selection of an appropriate framework material for the specific clinical situation. Furthermore, the findings suggest that subperiosteal implant treatment planning should account not only for the selection of the framework material but also for the mechanical resilience of the screws.