title: Three-Dimensional Nonlinear Finite Element Analysis and Microcomputed Tomography Evaluation of Microgap Formation in a Dental Implant Under Oblique Loading.
abstract: OBJECTIVE
  Since bacterial leakage along the implant-abutment interface may be responsible for peri-implant infections, a realistic estimation of the interface gap width during function is important for risk assessment. The purpose of this study was to compare two methods for investigating microgap formation in a loaded dental implant, namely, microcomputed tomography (micro-CT) and three-dimensional (3D) nonlinear finite element analysis (FEA); additionally, stresses to be expected during loading were also evaluated by FEA.
  
  
  METHODS
  An implant-abutment complex was inspected for microgaps between the abutment and implant in a micro-CT scanner under an oblique load of 200 N. A numerical model of the situation was constructed; boundary conditions and external load were defined according to the experiment. The model was refined stepwise until its load-displacement behavior corresponded sufficiently to data from previous load experiments. FEA of the final, validated model was used to determine microgap widths. These were compared with the widths as measured in micro-CT inspection. Finally, stress distributions were evaluated in selected regions.
  
  
  RESULTS
  No microgaps wider than 13 μm could be detected by micro-CT for the loaded implant. FEA revealed gap widths up to 10 μm between the implant and abutment at the side of load application. Furthermore, FEA predicted plastic deformation in a limited area at the implant collar.
  
  
  CONCLUSIONS
  FEA proved to be an adequate method for studying microgap formation in dental implant-abutment complexes. FEA is not limited in gap width resolution as are radiologic techniques and can also provide insight into stress distributions within the loaded complex.
authors.forename: Daniela
authors.initials: D
authors.lastname: Jörn
authors.forename: Philipp
authors.initials: P
authors.lastname: Kohorst
authors.forename: Silke
authors.initials: S
authors.lastname: Besdo
authors.forename: Lothar
authors.initials: L
authors.lastname: Borchers
authors.forename: Meike
authors.initials: M
authors.lastname: Stiesch
mesh_terms: D000044:Dental Abutments; D059605:Dental Implant-Abutment Design / Q000592:standards*; D003758:Dental Implantation, Endosseous / Q000379:methods*; D015921:Dental Implants; D003799:Dental Stress Analysis / Q000379:methods; D020342:Finite Element Analysis; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D013314:Stress, Mechanical; D055114:X-Ray Microtomography
chemical_list: D015921:Dental Implants