Influence of Various Implant Placement Strategies on Stress Distribution in Maxillary Implant-Retained Overdenture: A 3D Finite-Element Analysis.

Abstract

<h4>Objectives</h4>This study used three-dimensional (3D) finite-element analysis (FEA) to investigate the effect of different implant placement strategies on the biomechanical behavior of implant-supported maxillary overdentures, and provide an initial guide to clinical treatment.<h4>Materials and methods</h4>For an edentulous maxilla, six different implant-supported overdenture models with various implant placement strategies were created using CATIA software. The reference model (5R-3R-3L-5L) featured symmetrical implant placement in the canine and second premolar regions bilaterally. Five additional models incorporated asymmetrical implant placement strategies: 5R-3R-1L-3L, 5R-2R-3L-5L, 5R-4R-3L-5L, 4R-3R-3L-5L, and 6R-3R-3L-5L. All models had identical bone properties, prosthetic components, material characteristics, and loading conditions. The geometric models were analyzed using ANSYS 24.0 Workbench software. The maximum principal stress for bone, and stress distribution patterns were analyzed, and the performance of the models was compared with the symmetrical reference model.<h4>Results</h4>The quantitative and qualitative results showed that the implant placement strategy significantly influenced the magnitude and distribution of stress. The symmetrical implant placement strategy demonstrated the most favorable stress distribution, with the lowest maximum stress values in positions 5 R (2.69 MPa), 3 R (2.25 MPa), 3 L (2.16 MPa), and 5 L (3.24 MPa). Placement of implants in the anterior region resulted in stress concentration in the anterior region with maximum stress values at positions 5 R (3.24 MPa), 3 L (3.96 MPa), 1 L (5.09 MPa), and 3 L (5.57 MPa). Asymmetrical implant placement strategies with increased anteroposterior distribution and more posterior placement also demonstrated favorable biomechanical performance. Certain asymmetrical patterns induced fulcrum effects, leading to heterogeneous stress distribution.<h4>Conclusions</h4>The symmetrical (5R-3R-3L-5L) implant placement may provide a more uniform stress distribution, which may enhance peri-implant bone preservation and long-term implant stability. Implant placement in the canine region should be prioritized, while mesially-positioned implants warrant clinical caution due to higher stress levels in bilaterally symmetrical implant placement strategies.