Biomechanical Evaluation of Anterior Implant-Supported Fixed Bridges Combined with Distal-Extension Removable Partial Dentures

This study compared the biomechanical performance of anterior two implant-supported fixed prostheses combined with distal-extension removable partial dentures (DERPDs) classified as Mandibular Kennedy Class I, incorporating metal clasps and extracoronal precision attachments, against conventional Locator®- and bar-attached implant overdenture prostheses under vertical and oblique bilateral posterior biting forces using three-dimensional finite element analysis. Four prosthetic designs with different retention systems were analyzed: an overdenture with a Locator® attachment, an overdenture with a bar attachment, an anterior implant-supported fixed bridge retaining a removable partial denture with clasp retention, and an anterior implant-supported fixed bridge retaining a removable partial denture with a precision attachment. Stress values and distributions were compared among the models using three-dimensional (3D) finite element analysis (FEA). Clasp attachments exhibited the lowest stress concentrations, while precision attachments showed the highest stress values. Overdentures with bar attachments demonstrated higher stress concentrations compared to Locator® attachments. Clasp-type attachments induced less stress on implants and peri-implant tissues while causing greater posterior tissue stress compared to extracoronal precision attachments in DERPDs. It can be considered a viable treatment for patients seeking an anterior implant-supported fixed bridge for esthetic and psychological reasons, and this can increase the patient's self-confidence.