title: Finite element stress analysis of edentulous mandibles with different bone types supporting multiple-implant superstructures.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the influence of different types of bone on the stress distribution in the mandibular bone supporting a prefabricated bar-type implant prosthesis using three-dimensional finite element analysis.
  
  
  METHODS
  Four finite element models (M) of a completely edentulous mandibular arch were built. The bone types varied from type 1 to type 4 (M1, M2, M3, M4). The arch was restored using a prefabricated bar system supported by four interforaminal implants for the protocol prosthesis. Computer software was used to determine the stress fields. Three unilateral posterior loads (L) of 150 N were exerted on the prosthesis: L1, perpendicular to the prefabricated bar; L2, oblique (30 degrees) in the buccolingual direction; and L3, oblique (30 degrees) in the linguobuccal direction. The maximum principal stress (Omax) and the maximum principal strain (Emax) were obtained for cortical and trabecular bone.
  
  
  RESULTS
  Types 3 and 4 bone showed the highest smax (MPa) in the cortical bone (19.9 and 18.2 for L1, 34.6 and 31.3 for L2, and 3.88 and 24.4 for L3, respectively). The maximum principal strain (Emax) was observed in type 4 cortical bone for all loads (1.80 for L1, 2.4 for L2, and 2.36 for L3).
  
  
  CONCLUSIONS
  The cortical bone in M3 and M4 showed the highest stress concentration in the axial and buccolingual loading conditions. Bone types 1 and 2 showed the lowest stress concentrations. For the linguobuccal loading condition, the cortical bone in M4 showed the highest stress concentration, followed by bone types 3, 2, and 1. Cortical bone in M4 showed the highest strain for all loading conditions. The bone type might not be the only decisive factor to influence the stress distribution the bone supporting an implant prosthesis anchored by a prefabricated bar.
authors.affiliation: Department of Prosthodontics, Aracatuba School of Dentistry, UNESP- Sao Paulo State University, Sao Paulo, Brazil.
authors.forename: Ericka Oliverira
authors.initials: EO
authors.lastname: de Almeida
authors.forename: Eduardo Passos
authors.initials: EP
authors.lastname: Rocha
authors.forename: Amilcar Chagas
authors.initials: AC
authors.lastname: Freitas
authors.forename: Manoel Martin
authors.initials: MM
authors.lastname: Freitas
mesh_terms: D000539:Alveolar Process / Q000503:physiopathology*; D001696:Biomechanical Phenomena; D015519:Bone Density; D003198:Computer Simulation; D003758:Dental Implantation, Endosseous; D015921:Dental Implants; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D003799:Dental Stress Analysis; D020342:Finite Element Analysis; D006801:Humans; D007575:Jaw, Edentulous / Q000503:physiopathology*; D008334:Mandible / Q000503:physiopathology*; D003765:Models, Dental; D013314:Stress, Mechanical
chemical_list: D015921:Dental Implants