title: Platform switching: biomechanical evaluation using three-dimensional finite element analysis.
abstract: OBJECTIVE
  The objective of this study was to evaluate, using three-dimensional finite element analysis (3D FEA), the stress distribution in peri-implant bone tissue, implants, and prosthetic components of implant-supported single crowns with the use of the platform-switching concept.
  
  
  METHODS
  Three 3D finite element models were created to replicate an external-hexagonal implant system with peri-implant bone tissue in which three different implant-abutment configurations were represented. In the regular platform (RP) group, a regular 4.1-mm-diameter abutment (UCLA) was connected to regular 4.1-mm-diameter implant. The platform-switching (PS) group was simulated by the connection of a wide implant (5.0 mm diameter) to a regular 4.1-mm-diameter UCLA abutment. In the wide-platform (WP) group, a 5.0-mm-diameter UCLA abutment was connected to a 5.0-mm-diameter implant. An occlusal load of 100 N was applied either axially or obliquely on the models using ANSYS software.
  
  
  RESULTS
  Both the increase in implant diameter and the use of platform switching played roles in stress reduction. The PS group presented lower stress values than the RP and WP groups for bone and implant. In the peri-implant area, cortical bone exhibited a higher stress concentration than the trabecular bone in all models and both loading situations. Under oblique loading, higher intensity and greater distribution of stress were observed than under axial loading. Platform switching reduced von Mises (17.5% and 9.3% for axial and oblique loads, respectively), minimum (compressive) (19.4% for axial load and 21.9% for oblique load), and maximum (tensile) principal stress values (46.6% for axial load and 26.7% for oblique load) in the peri-implant bone tissue.
  
  
  CONCLUSIONS
  Platform switching led to improved biomechanical stress distribution in peri-implant bone tissue. Oblique loads resulted in higher stress concentrations than axial loads for all models. Wide-diameter implants had a large influence in reducing stress values in the implant system.
authors.affiliation: Department of Dental Materials and Prosthodontics, Univ Estadual Paulista, São Paulo, Brazil.
authors.forename: Lucas Fernando
authors.initials: LF
authors.lastname: Tabata
authors.forename: Eduardo Passos
authors.initials: EP
authors.lastname: Rocha
authors.forename: Valentim Adelino Ricardo
authors.initials: VA
authors.lastname: Barão
authors.forename: Wirley Goncalves
authors.initials: WG
authors.lastname: Assunção
mesh_terms: D000539:Alveolar Process / Q000502:physiology; D001696:Biomechanical Phenomena; D016723:Bone Remodeling / Q000502:physiology; D003442:Crowns; D000044:Dental Abutments; D019250:Dental Implants, Single-Tooth; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D003799:Dental Stress Analysis; D020342:Finite Element Analysis; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008422:Materials Testing; D016348:Osseointegration / Q000502:physiology; D013314:Stress, Mechanical