Evaluation of Retentive Forces in Three Types of Removable Partial Denture Framework Materials: An In Vitro Study

Introduction The utilization of Computer-Aided Design and Computer-Aided Manufacturing (CAD/CAM) technology in the production of polyetheretherketone (PEEK) and acetal frameworks enhances the precision and stability of partial denture frameworks. This study evaluates the retentive forces of CAD/CAM-fabricated PEEK, acetal, and cobalt-chromium (Co-Cr) frameworks in removable partial dentures (RPDs). Methods Forty-five frameworks were fabricated (15 each of PEEK, acetal, and Co-Cr) and tested for retentive forces using a universal testing machine at a crosshead speed of 5 mm/min. The frameworks were divided into three groups: one with digitally milled PEEK, one with Co-Cr, and one with digitally milled acetal. Each partial denture clasp was designed using CAD/CAM software, extending between the central incisor and the second premolar. These clasps were specifically designed to aid in securing the framework during tensile testing and to facilitate the removal of cast clasps during later stages. Results PEEK frameworks demonstrated the highest retentive forces (mean: 3.52 ± 0.78 N, p < 0.001), followed by acetal (mean: 0.47 ± 0.02 N) and Co-Cr (mean: 0.32 ± 0.12 N). Conclusions PEEK outperformed other materials, making it a promising candidate for RPD frameworks.