LAUSR

Purpose: Biomechanical behavior of tooth-implant–supported prostheses (TISPs) with external and internal implants was compared. Materials and Methods: Two 3-D models of TISP were designed by varying the implant: external (Model EH) and internal hexagons (Model IH). After loading, von Mises stresses were obtained in implants, abutments, and screws. Principal maximum (&sgr;max) and minimum (&sgr;min) stresses were analyzed in periodontal ligament (PL), alveolar bone, and periimplant bone. Results: Model IH showed lower stress peaks in axial loading in the implant and in the screw but higher in abutment. In oblique loading, Model IH had lower stresses in the implant, but higher in the abutment and in the screw. In the &sgr;max analysis for axial and oblique loads, stress peaks in Model IH were lower in PL, alveolar bone, and periimplant bone. In the &sgr;min analysis for axial load, stress peaks in Model IH were lower in PL, but higher in alveolar bone and in periimplant bone. In oblique load, Model IH showed lower stress peaks in PL and alveolar bone, but higher stress peaks in periimplant bone. Conclusions: TISPs with IH implants do present lower risk of biomechanical failure.