Biomechanical Evaluation of Different Posterior Mandibular Implant Configurations Under Bruxism: An FEA Study

This study evaluated the biomechanical performance of different abutment types, superstructure materials, prosthetic designs, and loading conditions in the implant-supported rehabilitation of three consecutive missing teeth in the mandibular posterior region using three-dimensional finite element analysis (3D-FEA). Twenty FEA models were constructed, simulating two-implant (pontic, mesial, and distal cantilever) and three-implant (splinted and unsplinted) configurations using multi-unit and Ti-base abutments composed of titanium alloy (Grade 5, Ti-6Al-4V), with monolithic zirconia and zirconia-supported feldspathic porcelain superstructures. Functional and parafunctional (bruxism) vertical and oblique loads were applied to analyze von Mises stresses in the components and principal stresses in the peri-implant bone. The results indicated that two-implant models generated higher stress concentrations than three-implant models, and unsplinted or cantilevered designs produced elevated stresses compared to splinted or pontic designs. Ti-base abutments resulted in greater stress accumulation in the connection complex compared to multi-unit systems. Under vertical and oblique parafunctional forces, stress values on the abutments in distal cantilever models-particularly in unsplinted Ti-base designs under oblique loading-exceeded the yield strength of the Ti-6Al-4V alloy (890 MPa), indicating a substantial risk of plastic deformation. To optimize biomechanical stability, three-implant-supported, splinted designs utilizing Multi-unit abutments should be prioritized. Avoiding distal cantilevers and unsplinted designs is critical in patients with bruxism to minimize the risk of mechanical failure in the Ti-6Al-4V components.