title: The influence of abutment angulation on micromotion level for immediately loaded dental implants: a 3-D finite element analysis.
abstract: OBJECTIVE
  To investigate the micromotion between the implant and surrounding bone caused by the implementation of an angled abutment for an immediately loaded single dental implant located in the anterior maxilla.
  
  
  METHODS
  A simplified half premaxillary bone model was fabricated. The dimension of the alveolar ridge was adopted from a dry human skull. Based on Brånemark protocol for Mk IV implants in type-3 bone, an immediate loading model was developed by press-fitting a 4-mm-diameter cylinder implant into a 3.15-mm osteotomy site in a numeric model. Material properties were assigned to the simulated model, and the model was meshed. A bite force of 89 N was applied to the tops of the 0-degree, 15-degree, and 25-degree angled abutments at a 120-degree angle to the abutment long axis. The micromotion between the bone-implant interfaces was calculated using ANSYS 9.0 software featuring a nonlinear contact algorithm.
  
  
  RESULTS
  The micromotion values for 15-degree and 25-degree angled abutments were 119% and 134%, respectively, compared to the corresponding values for straight abutments. Compared to straight abutments, the 25-degree abutments resulted in increased maximum von Mises stresses to a level of 18%. Most of the stresses were concentrated within the cortical bone around the neck of the implants.
  
  
  CONCLUSIONS
  Within the limits of the present finite element analysis study, abutment angulation up to 25 degrees can increase the stress in the peri-implant bone by 18% and the micromotion level by 30%.
authors.affiliation: Joint Prosthesis Technology Research Center and Institute of Biomechanical Engineering, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Hung-Chan
authors.initials: HC
authors.lastname: Kao
authors.forename: Yih-Wen
authors.initials: YW
authors.lastname: Gung
authors.forename: Tai-Foong
authors.initials: TF
authors.lastname: Chung
authors.forename: Ming-Lun
authors.initials: ML
authors.lastname: Hsu
mesh_terms: D000465:Algorithms; D002102:Cadaver; D003198:Computer Simulation; D000044:Dental Abutments; D003758:Dental Implantation, Endosseous / Q000379:methods*; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D003799:Dental Stress Analysis / Q000379:methods; D020342:Finite Element Analysis; D006801:Humans; D008437:Maxilla; D009068:Movement; D013997:Time Factors; D016474:Weight-Bearing