title: Three-dimensional finite element analysis of the effect of 1-piece superstructure on mandibular flexure.
abstract: OBJECTIVE
  Mandibular flexure may affect the stress distribution in the implant-supported fixed partial dentures, yet the phenomenon has received little attention in finite element analysis studies. The purpose of this study was to evaluate the restraining effects imposed by 1-piece cross-arch superstructure on mandibular flexure and implant stresses.
  
  
  METHODS
  Mandibular deformation and stress distribution in an implant-supported prosthesis (5 implants and 1-piece superstructure with 16.5 mm bilateral distal cantilevers) were analyzed by a 3-dimensional finite element model of a human edentulous mandible. To determine the effect of 1-piece cross-arch superstructure on mandibular flexure restriction, incisal clenching was simulated. During incisal clenching, maximum contraction of dental arch occurs. For this purpose, 9 pairs of masticatory muscles were simulated by multiple force vectors over areas of attachment.
  
  
  RESULTS
  A significant amount of stress (26.2 MPa) at the cortical bone surrounding the neck of the implant located at the symphysis assumed as a consequence of mandibular flexure. At the same area, maximum strain value of 1680 microstrain was detected. Moreover, maximum deformation of 0.35 mm was observed at the mandibular angle.
  
  
  CONCLUSIONS
  One-piece implant-supported superstructure restricted mandibular deformation to almost half of the amount observed in unrestricted mandibular models of previous studies. This phenomenon must be considered in finite element analysis studies.
authors: Department of Fixed Prosthodontics and Occlusion, Faculty of Dentistry, Dental Research Center, Tehran University of Medical Sciences, Tehran, Iran. robaghai@yahoo.com
authors: Roshanak Baghai
authors: RB
authors: Naini
authors: Saied
authors: S
authors: Nokar
mesh_terms: D001696:Biomechanical Phenomena; D001732:Bite Force; D003198:Computer Simulation; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D003799:Dental Stress Analysis / Q000379:methods; D003830:Denture, Partial, Fixed; D004548:Elasticity; D020342:Finite Element Analysis; D006801:Humans; D021621:Imaging, Three-Dimensional; D007575:Jaw, Edentulous / Q000503:physiopathology; D008334:Mandible / Q000502:physiology*; D008410:Masticatory Muscles / Q000502:physiology; D008953:Models, Anatomic; D018583:Pliability; D013314:Stress, Mechanical