Three-dimensional finite element analysis of zygomatic and pterygoid implants for the rehabilitation of severely atrophic maxilla.

It remains uncertain whether replacing posterior zygomatic implants with pterygoid implants reduces the stress exerted on anterior zygomatic implants in the canine region. This three-dimensional finite element analysis (FEA) study aims to compare stress and strain patterns between two implant configurations under the influence of masticatory muscle forces. A 3D (FEM) model of an edentulous, atrophic maxilla was developed using data from a cone-beam computed tomography (CBCT) scan. Two configurations were examined: Model A, which included bilateral zygomatic implants, and Model B, featuring one zygomatic and one pterygoid implant. Virtual implant placement was carried out, and corresponding prosthetic superstructures were designed for each model. The simulation assessed stress distribution within the bone, implants, and prosthetic components under three loading conditions: a 150 N vertical force, a 50 N lateral force, and a 300 N distributed occlusal load applied at the masseter muscle's insertion on the zygomatic arch. Von Mises stress maps were used to visualize stress patterns in the peri-implant bone, abutments, and prosthetic framework. Additionally, maximum principal stress and micromotion were evaluated to assess implant stability and predict osseointegration potential. The FEA results revealed notable stress concentrations at the abutments of both posterior zygomatic and pterygoid implants in each model. However, Model B, which utilized a pterygoid implant, showed a more balanced distribution of occlusal forces at the anterior implant-abutment interface, maintaining stress levels within physiological limits. Moreover, Model A exhibited nearly twice the micromotion observed in Model B. These findings indicate that the abutment interface is a primary zone of stress concentration under simulated masticatory forces. Overall, the study concludes that incorporating pterygoid implants enhances load distribution and reduces cantilever effects due to a broader anteroposterior implant spread. Nonetheless, both implant types experienced peak stresses at the abutment interface, suggesting this region may be prone to mechanical complications over time.