title: Effect of geometric parameters on finite element analysis of bone loading caused by nonpassively fitting implant-supported dental restorations.
abstract: OBJECTIVE
  Finite element analysis (FEA) has been frequently used to study the loading situation of dental implants and bone resulting from the fixation of nonpassively fitting restorations. The goal of the present investigation was to demonstrate the effect of geometric model parameters and mesh size on FEA results.
  
  
  METHODS
  Five three-dimensional FEA models representing a three-unit fixed dental prosthesis (FDP) supported by two terminal implants were constructed. The models differed in terms of mesh size, bone geometry, implants, and restoration and were created either by joining virtual free-form objects or utilizing optical scans of existing components. By applying thermal changes in volume of specific elements in the area of the FDP pontic, a horizontal misfit of 10 Μm between implants and the restoration was introduced. The resulting loading situation of the bone around the implants was recorded as von Mises equivalent stress.
  
  
  RESULTS
  Maximum stress magnitudes ranging from 13.1 to 24.9 MPa occurred in the cortical part of the implant site where the neck of the implant penetrates bone. In trabecular bone, loading magnitudes were lower by a factor of 20. Modeling implant threads did have a remarkable effect on the stress situation as well as different span lengths of the restorations modeled. All other parameters led only to small variations in maximum loading magnitudes.
  
  
  CONCLUSIONS
  Simplistic FEA models based on virtual free-form objects with limited level of mesh refinement seem to allow for a basic evaluation of peri-implant bone loading resulting from the fixation of misfitting superstructures.
authors.affiliation: Department of Mechanical Engineering, University of Erlangen-Nuremberg, Erlangen, Germany.
authors.forename: Werner
authors.initials: W
authors.lastname: Winter
authors.forename: Paul
authors.initials: P
authors.lastname: Steinmann
authors.forename: Stefan
authors.initials: S
authors.lastname: Holst
authors.forename: Matthias
authors.initials: M
authors.lastname: Karl
mesh_terms: D000539:Alveolar Process / Q000502:physiology*; D001696:Biomechanical Phenomena; D003198:Computer Simulation; D000044:Dental Abutments; D003738:Dental Cements / Q000737:chemistry; D015921:Dental Implants; D018772:Dental Marginal Adaptation; D019094:Dental Prosthesis, Implant-Supported; D003779:Denture Design; D003781:Denture Retention; D003830:Denture, Partial, Fixed; D055119:Elastic Modulus; D020342:Finite Element Analysis; D006801:Humans; D021621:Imaging, Three-Dimensional; D008954:Models, Biological; D013314:Stress, Mechanical; D013499:Surface Properties
chemical_list: D003738:Dental Cements; D015921:Dental Implants