Finite Element Analysis of Implant-Assisted Mandibular Distal Extension Removable Partial Denture: Evaluating Stress Distribution in Premolar Versus Molar Implant Positions-An In-Silico Study.

Background and aim: This study aimed to compare the influence of implant support on mandibular distal extension removable partial dentures (RPD) by evaluating load distribution on implants positioned at different locations. The objective was to identify the most biomechanically suitable design for implant-assisted removable partial dentures (IARPD).

Methods: A mandibular bilateral partially edentulous model, replicating the absence of premolars and molars, was fabricated using epoxy resin. Two implants of identical diameter were vertically positioned in the edentulous ridge, one at the second molar and the other at the second premolar region on each side, to assess the biomechanical impact of different implant placements. A finite element model (FEM) was developed by taking cone-beam computed tomography (CBCT) scan of physical model to compare two implant-supported denture designs based on implant positioning. The geometry was created in IGS (Interactive Graphic System) format and imported into the ANSYS design modeler application. It was then transferred to the ANSYS mechanical application, where meshing was performed to generate the finite element model for load application. The occlusal surface of the prosthesis was designated as the area for applying loads of 100 N and 125 N. Von Mises stress and displacement was evaluated in premolar (Group I) versus molar (Group II) implant positions.

Results: Finite element analysis revealed no statistically significant differences in von Mises stress and displacement values between premolar and molar implant positions (p > 0.05). The observed mean values were slightly greater in the premolar group, but these differences were not significant. In premolar versus molar implant positions (p > 0.05), with RPD framework stress at 125 N being 28.71 ± 1.10 MPa (Group I) versus 25.56 ± 4.89 MPa (Group II), suggesting comparable biomechanical performance regardless of implant placement.

Conclusion: The study suggests both premolar and molar implant positions are biomechanically viable for distal-extension RPDs, with no significant differences in stress distribution.