RESUMO
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 (σmax) and minimum (σmin) 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 σmax analysis for axial and oblique loads, stress peaks in Model IH were lower in PL, alveolar bone, and periimplant bone. In the σmin 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.
Assuntos
Dente Suporte , Projeto do Implante Dentário-Pivô , Implantes Dentários para Um Único Dente , Prótese Dentária Fixada por Implante , Fenômenos Biomecânicos , Parafusos Ósseos , Desenho Assistido por Computador , Análise do Estresse Dentário , Análise de Elementos Finitos , Mandíbula , Teste de Materiais , Modelos Dentários , Tomografia Computadorizada por Raios XRESUMO
PURPOSE: The goal of this study was to compare the stress distribution of tooth-implant-supported prostheses (TISPs) and solely implant-supported prostheses (ISPs) with two different pontic spans (three units versus four units). MATERIALS AND METHODS: Two-dimensional finite element models were constructed from the radiographs of polyester resin casts to mimic TISPs and ISPs. In all, eight models were analyzed. Occlusal loads of 15 N and 30 N were applied to the premolars and molars, respectively. The lateral and inferior borders of the models were constrained, with all degrees of freedom equal to zero. Eight-node elements with plane strain assumption were used for simulation. RESULTS: The authors found that TISPs with a short span and wider-diameter implants resulted in more homogenous stress distribution and less stress concentration on the implants. The long span yielded higher stress concentrations on the implants and between the pontics. CONCLUSIONS: In all models analyzed, stress concentrations were present in the implants.