Effect of the Number of Implants on Stress Distribution of Anterior Implant-Supported Fixed Prostheses Combined With A Removable Partial Denture: A Finite Element Analysis

Objective: the main goal of this study was to evaluate differences in stress distribution relevant to the number of implants under an anterior bridge when combined with a remov-able partial denture in the posterior region.materials and methods: four three-dimensional finite element models (3d fem) were designed from a mandible containing an implant-supported bridge extending between ca-nines, and a bilateral distal extension removable partial denture. a nonrigid connection was selected as the attachment method between the partial denture and the anterior im-plant-supported fixed prosthesis; 2, 3, 4 and 5 implants supporting the bridge all with 10mm length and 3.8 mm diameter were assessed. with the aid of the finite element pro-gram ansys 8.0, the models were loaded and von mises stresses were evaluated.results: in spongy bone, stress forces showed a decrease from 2 implants to 4 implants but showed an increase in the 5-implant model. stresses on cortical bone of terminal im-plants were in similar range in the 2-, 3- and 4-implant models. while, in the 5-implant model the amount of stresses on terminal implants increased dramatically. the stresses on implants were nearly similar in all models, with the greatest amount on terminal implants.conclusion: within the limitations of this study, 2-, 3- and 4-implant models showed less stress on cortical and spongy bone in comparison with the 5-implant model. the stresses transferred to implants were nearly similar.