title: Overdenture retaining bar stress distribution: a finite-element analysis.
abstract: OBJECTIVE
  Evaluate the stress distribution on the peri-implant bone tissue and prosthetic components of bar-clip retaining systems for overdentures presenting different implant inclinations, vertical misfit and framework material.
  
  
  METHODS
  Three-dimensional models of a jaw and an overdenture retained by two implants and a bar-clip attachment were modeled using specific software (SolidWorks 2010). The studied variables were: latero-lateral inclination of one implant (-10°, -5°, 0°, +5°, +10°); vertical misfit on the other implant (50, 100, 200 µm); and framework material (Au type IV, Ag-Pd, Ti cp, Co-Cr). Solid models were imported into mechanical simulation software (ANSYS Workbench 11). All nodes on the bone's external surface were constrained and a displacement was applied to simulate the settling of the framework on the ill-fitted component. Von Mises stress for the prosthetic components and maximum principal stress to the bone tissue were evaluated.
  
  
  RESULTS
  The +10° inclination presented the worst biomechanical behavior, promoting the highest stress values on the bar framework and peri-implant bone tissue. The -5° group presented the lowest stress values on the prosthetic components and the lowest stress value on peri-implant bone tissue was observed in -10°. Increased vertical misfit caused an increase on the stress values in all evaluated structures. Stiffer framework materials caused a considerable stress increase in the framework itself, prosthetic screw of the fitted component and peri-implant bone tissue.
  
  
  CONCLUSIONS
  Inclination of one implant associated with vertical misfit caused a relevant effect on the stress distribution in bar-clip retained overdentures. Different framework materials promoted increased levels of stress in all the evaluated structures.
authors: Prosthesis and Periodontics.
authors: Conrado Reinoldes
authors: CR
authors: Caetano
authors: Marcelo Ferraz
authors: MF
authors: Mesquita
authors: Rafael Leonardo Xediek
authors: RL
authors: Consani
authors: Lourenço
authors: L
authors: Correr-Sobrinho
authors: Mateus Bertolini Fernandes
authors: MB
authors: Dos Santos
mesh_terms: D000539:Alveolar Process / Q000502:physiology; D001696:Biomechanical Phenomena; D002858:Chromium Alloys / Q000737:chemistry; D003198:Computer Simulation; D003722:Dental Alloys / Q000737:chemistry; D015921:Dental Implants; D018772:Dental Marginal Adaptation; D003764:Dental Materials / Q000737:chemistry; D019094:Dental Prosthesis, Implant-Supported; D003781:Denture Retention / Q000295:instrumentation*; D003828:Denture, Overlay; D004548:Elasticity; D020342:Finite Element Analysis; D006047:Gold Alloys / Q000737:chemistry; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008422:Materials Testing; D008954:Models, Biological; D010165:Palladium / Q000737:chemistry; D012834:Silver / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry
chemical_list: D002858:Chromium Alloys; D003722:Dental Alloys; D015921:Dental Implants; D003764:Dental Materials; D006047:Gold Alloys; D012834:Silver; D010165:Palladium; D014025:Titanium
keywords: finite element analysis; implant inclination; misfit; overdenture