title: Use of an axisymmetric finite element method to compare maxillary bone variables for a loaded implant.
abstract: OBJECTIVE
  This study determined the effect of various bone models on the stresses and strains generated under occlusal loading of a dental implant.
  
  
  METHODS
  A two-dimensional finite-element model was created for stress analysis. The geometric and elastic properties of a 3.8 x 10-mm Steri-Oss implant embedded in a segment of premaxilla were modeled. Computed tomography scanning of a dried maxilla half was used to determine representative geometry and density of this region. Material properties for bone were varied to simulate the following: all-cancellous bone, cancellous bone with a thin (1.5-mm) crestal isotropic cortical layer, cancellous bone with a thick (3-mm) crestal isotropic cortical layer, and cancellous bone with a thick (3-mm) layer of transversely isotropic (orthotropic) cortical bone.
  
  
  RESULTS
  Low stresses and high strains surrounded the fixture apex for the all-cancellous bone model. When a layer of cortical bone was added, higher crestal stresses and lower apical strains were observed. The thicker layer of isotropic cortical bone produced stresses at least 50% less than the thinner layer. The assumption of transverse isotropy (orthotropy) increased stresses and strains by approximately 25% compared with isotropic bone.
  
  
  CONCLUSIONS
  Crestal cortical layer thickness and bone isotropy have a substantial impact on resultant stresses and strains. Clinical assessment of these parameters is recommended.
authors.affiliation: Section of Restorative and Prosthetic Dentistry, College of Dentistry, Ohio State University.
authors.forename: N L
authors.initials: NL
authors.lastname: Clelland
authors.forename: J K
authors.initials: JK
authors.lastname: Lee
authors.forename: O C
authors.initials: OC
authors.lastname: Bimbenet
authors.forename: A
authors.initials: A
authors.lastname: Gilat
mesh_terms: D000539:Alveolar Process / Q000033:anatomy & histology / Q000502:physiology; D001696:Biomechanical Phenomena; D015519:Bone Density; D015921:Dental Implants; D003799:Dental Stress Analysis / Q000379:methods*; D004548:Elasticity; D006801:Humans; D008437:Maxilla / Q000033:anatomy & histology* / Q000502:physiology*; D011312:Pressure; D013718:Tensile Strength
chemical_list: D015921:Dental Implants