Influence of Framework Material on Biomechanical Performance of an All-on-4 Prosthesis Supported by Bendable Monoblock Implants.

The purpose of this study was to use the finite element analysis method to determine the influence of framework material on stresses in different parts of a model of an All-on-4 prosthesis supported by bendable monoblock implants. A three-dimensional solid model of an edentulous mandible was reconstructed from computed tomography data and segmented using 3DSlicer. Four bendable monoblock implants were positioned in accordance with the All-on-4 configuration. Screw-retained prostheses were modeled with the framework considered fabricated using one of five materials. These were cobalt-chromium (Co-Cr) alloy, titanium (Ti) alloy, polyetheretherketone (PEEK), polyetherketoneketone (PEKK), and a glass fiber-reinforced polymer composite (FRC) material. Four types of clinically relevant loads (300 N) were applied statically, namely, unilateral oblique, unilateral vertical, bilateral oblique, and bilateral vertical. Maximum and minimum principal stresses were determined in the cortical bone, and maximum von Mises stress was determined in each of the other parts of the model. Across most loading conditions, PEEK and PEKK showed higher stress values in the cortical bone and in the implants. In the screws, PEEK and PEKK also showed higher stress values, except in the anterior implant screws under bilateral loading conditions. In the framework, the highest stresses were obtained when a metal was the material of fabrication. Across all loading conditions, with FRC, the stress transfer was balanced. Thus, the prevent results suggest that FRC may be a suitable alternative to metallic materials for fabricating the framework of an All-on-4 prosthesis supported by bendable monoblock implants.