title: A numerical method for predicting the bending fatigue life of NiTi and stainless steel root canal instruments.
abstract: OBJECTIVE
  To evaluate the bending fatigue lifetime of nickel-titanium alloy (NiTi) and stainless steel (SS) endodontic files using finite element analysis.
  
  
  METHODS
  The strain-life approach was adopted and two theoretical geometry profiles, the triangular (TR) and the square cross-sections, were considered. Both low-cycle fatigue (LCF) lifetime and high-cycle fatigue (HCF) lifetime were evaluated.
  
  
  RESULTS
  The bending fatigue behaviour was affected by the material property and the cross-sectional configuration of the instrument. Both the cross-section factor and material property had a substantial impact on fatigue lifetime. The NiTi material and TR geometry profiles were associated with better fatigue resistance than that of SS and square cross-sections.
  
  
  CONCLUSIONS
  Within the limitations of this study, finite element models were established for endodontic files to prejudge their fatigue lifetime, a tool that would be useful for dentist to prevent premature fatigue fracture of endodontic files.
authors.affiliation: Area of Endodontics, Comprehensive Dental Care, Faculty of Dentistry, the University of Hong Kong, Hong Kong, Hong Kong Special Administrative Region.
authors.forename: G S P
authors.initials: GS
authors.lastname: Cheung
authors.forename: E W
authors.initials: EW
authors.lastname: Zhang
authors.forename: Y F
authors.initials: YF
authors.lastname: Zheng
mesh_terms: D003722:Dental Alloys; D003762:Dental Instruments; D003799:Dental Stress Analysis / Q000379:methods*; D004867:Equipment Design; D004868:Equipment Failure; D020342:Finite Element Analysis; D009532:Nickel; D018583:Pliability; D018915:Root Canal Preparation / Q000295:instrumentation*; D013193:Stainless Steel; D014025:Titanium; D019415:Torque
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D013193:Stainless Steel; D009532:Nickel; D014025:Titanium