Finite Element Analysis of Maxillary Overdentures Supported by Two, Three, and Four Implants

This study aimed to evaluate, through finite element analysis (FEA), the biomechanical behavior of edentulous maxillary overdentures supported on 2, 3, and 4 implants with conometric connections, and to determine the minimum implant number that maintains stresses within physiological limits. A 3D finite element model of a resorbed edentulous maxilla was generated from CT images and processed in ANSYS v19.0. Subsequently, six models were simulated according to implant number (2, 3, or 4) and cortical bone thickness (0.5 mm or 1 mm). Conical connection implants and cobalt-chromium-reinforced overdentures with Equator attachments were modeled. Bilateral axial loads were applied and Von Mises equivalent stresses were calculated for implants and abutments, while maximum and minimum principal stresses were analyzed in bone. Results showed that the highest deformation and stress concentrations were observed in the two-implant models, with trabecular stresses ranging from 6.5 to 8.4 MPa, exceeding the 5 MPa safety threshold. In contrast, both three- and four-implant models maintained trabecular stresses below 3 MPa, while keeping cortical bone stresses within physiological limits. The three-implant tripod configuration demonstrated a comparable stress distribution to the four-implant models. From a biomechanical perspective, overdentures supported on four implants with 1 mm cortical thickness showed the most favorable performance. Nevertheless, the three-implant model represented a biomechanically acceptable and potentially cost-effective alternative, suggesting its viability as a simplified clinical option that warrants further investigation.