Biomechanical comparison of various implant inclinations and abutment types in a bendable implant system

Abstract Background This study aims to evaluate the stress distribution in peri-implant bone, implant surfaces, and within the framework material under vertical and oblique loads, considering various angulations and abutment types of bendable one-piece implants in the All-on-4 concept. Methods A three-dimensional model of an edentulous mandible was constructed. Six different configurations were modeled according to prosthesis connection type and inclination of the posterior implants based on the All-on-4 protocol. Four one-piece implants were placed in each model and a cobalt-chromium frameworks with 14 mm cantilever lengths were designed. Under vertical and oblique loading conditions, maximum principal stress and minimum principal stress values were obtained for cortical and trabecular bone and von Mises stress values were calculated for implants and frameworks. Results Implant angulation, connection type, and loading conditions affected stress distribution in the peri-implant bone, implants, and frameworks. Higher stress values were observed in posterior implants with increased angulation. Screw-retained models demonstrated greater stress values compared to cement-retained ones under both loading conditions. Conclusions For optimal stress distribution in peri-implant bone and frameworks, cement-retained prosthesis may be preferred, especially in cases with increased implant angulation in one-piece bendable systems. Additionally, careful consideration of posterior implant angulation and loading conditions is crucial to minimize the excessive stress and to enhance long-term stability. Clinical trial number Not applicable.