Comparison of biomechanical performance of custom implants with different designs under functional load: a finite element analysis

OBJECTIVE: Rehabilitation of severely atrophic edentulous maxillae is clinically challenging because of limited bone volume and the constraints of conventional implants. Recent advances in digital planning and additive manufacturing have increased interest in patient-specific titanium subperiosteal implants. This study aimed to compare the biomechanical performance of 6 titanium subperiosteal implant designs for fixed prosthetic rehabilitation. METHODS: A three-dimensional atrophic maxilla model was reconstructed from Visible Human Project tomography data. 6 subperiosteal implant designs, comprising three single-piece and three 2-piece configurations, were modeled using CAD software. Abutments were positioned at the 2nd, 4th, and 6th tooth regions. Vertical (150 N) and oblique (50 N at 30°) masticatory loads were applied. All materials were assumed to be homogeneous, isotropic, and linearly elastic. Maximum principal stress, minimum principal stress, and von Mises stress distributions were evaluated in the implant, abutment, prosthetic framework, and surrounding bone. RESULTS: Stress distribution patterns were comparable under vertical and oblique loading. Single-piece designs exhibited lower von Mises stress values within the implant, whereas 2-piece designs showed reduced stress transfer to the surrounding bone. Mesh-type designs generated the highest implant stresses but lower stresses in the abutment, prosthetic framework, and bone. Peak cortical bone stresses remained within physiologically acceptable limits and were mainly concentrated in the nasal buttress region. CONCLUSION: Subperiosteal implant biomechanics are strongly influenced by design and configuration. Single-piece designs favor implant-level stress reduction, while 2-piece designs appear advantageous for minimizing bone stress.