title: Influence of microthreads and platform switching on stress distribution in bone using angled abutments.
abstract: OBJECTIVE
  To evaluate the stress distribution in peri-implant bone by simulating the effect of an implant with microthreads and platform switching on angled abutments through tridimensional finite element analysis. The postulated hypothesis was that the presence of microthreads and platform switching would reduce the stress concentration in the cortical bone.
  
  
  METHODS
  Four mathematical models of a central incisor supported by an implant (5.0 mm × 13 mm) were created in which the type of thread surface in the neck portion (microthreaded or smooth) and the diameter of the angled abutment connection (5.0 and 4.1mm) were varied. These models included the RM (regular platform and microthreads), the RS (regular platform and smooth neck surface), the SM (platform switching and microthreads), and the SS (platform switching and smooth neck). The analysis was performed using ANSYS Workbench 10.0 (Swanson Analysis System). An oblique load (100N) was applied to the palatine surface of the central incisor. The bone/implant interface was considered to be perfectly integrated. Values for the maximum (σ(max)) and minimum (σ(min)) principal stress, the equivalent von Mises stress (σ(vM)), and the maximum principal elastic strain (ɛ(max)) for cortical and trabecular bone were obtained.
  
  
  RESULTS
  For the cortical bone, the highest σ(max) (MPa) were observed for the RM (55.1), the RS (51.0), the SM (49.5), and the SS (44.8) models. The highest σ(vM) (MPa) were found for the RM (45.4), the SM (42.1), the RS (38.7), and the SS models (37). The highest values for σ(min) were found for the RM, SM, RS and SS models. For the trabecular bone, the highest σ(max) values (MPa) were observed in the RS model (6.55), followed by the RM (6.37), SS (5.6), and SM (5.2) models.
  
  
  CONCLUSIONS
  The hypothesis that the presence of microthreads and a switching platform would reduce the stress concentration in the cortical bone was partially rejected, mainly because the microthreads increased the stress concentration in cortical bone. Only platform switching reduced the stress in cortical bone.
authors.affiliation: Post Graduate Center, São Leopoldo Mandic Dental School, Campinas, SP, Brazil.
authors.forename: Cacilda Cunha
authors.initials: CC
authors.lastname: Ferraz
authors.forename: Rodolfo Bruniera
authors.initials: RB
authors.lastname: Anchieta
authors.forename: Erika Oliveira
authors.initials: EO
authors.lastname: de Almeida
authors.forename: Amilcar Chagas
authors.initials: AC
authors.lastname: Freitas
authors.forename: Fábio Cunha
authors.initials: FC
authors.lastname: Ferraz
authors.forename: Lucas Silveira
authors.initials: LS
authors.lastname: Machado
authors.forename: Eduardo Passos
authors.initials: EP
authors.lastname: Rocha
mesh_terms: D000044:Dental Abutments; D059605:Dental Implant-Abutment Design; D015921:Dental Implants; D017267:Dental Prosthesis Design; D003799:Dental Stress Analysis; D006801:Humans; D008433:Mathematics; D008962:Models, Theoretical
chemical_list: D015921:Dental Implants