title: Evaluation of the resistance to cyclic fatigue among ProTaper Next, ProTaper Universal, and Vortex Blue rotary instruments.
abstract: BACKGROUND
  The purpose of this study was to compare the fracture resistance to cyclic fatigue of ProTaper Next (PTN; Dentsply Tulsa Dental Specialties, Tulsa, OK), ProTaper Universal (PTU, Dentsply Tulsa Dental Specialties), and Vortex Blue (VB, Dentsply Tulsa Dental Specialties) rotary instruments.
  
  
  METHODS
  Twenty instruments each of PTN X1-X5, PTU S1-F5, and VB 20/04-50/04 were rotated until fracture in a simulated canal of 90° and a 5-mm radius using a custom-made testing platform. The number of cycles to fracture (NCF) was calculated. Weibull analysis was used to predict the maximum number of cycles when 99% of the instrument samples survive.
  
  
  RESULTS
  VB 20/04-30/04 had significantly higher NCF than PTU S1-F5 and PTN X1-X5. VB 35/04-45/04 had significantly higher NCF than PTU S2-F5 and PTN X2-X5. PTN X1 had higher NCF than PTU S1-F5. PTN X2 had higher NCF than PTU F2-F5. The Weibull distribution predicted the highest number of cycles at which 99% of instruments survive to be 766 cycles for VB 25/04 and the lowest to be 50 cycles for PTU F2.
  
  
  CONCLUSIONS
  Under the limitations of this study, VB 20/04-45/04 were more resistant to cyclic fatigue than PTN X2-X5 and PTU S2-F5. PTN X1 and X2 were more resistant to cyclic fatigue than PTU F2-F5. The Weibull distribution appears to be a feasible and potentially clinically relevant model to predict resistance to cyclic fatigue.
authors: Department of Endodontics, School of Dentistry, University of Washington, Seattle, Washington. Electronic address: harrison_nguyen@yahoo.com.
authors: Harrison H
authors: HH
authors: Nguyen
authors: Department of Materials Science and Engineering, University of Washington, Seattle, Washington.
authors: Hanson
authors: H
authors: Fong
authors: Department of Endodontics, School of Dentistry, University of Washington, Seattle, Washington.
authors: Avina
authors: A
authors: Paranjpe
authors: Department of Endodontics, School of Dentistry, University of Washington, Seattle, Washington.
authors: Natasha M
authors: NM
authors: Flake
authors: Department of Endodontics, School of Dentistry, University of Washington, Seattle, Washington.
authors: James D
authors: JD
authors: Johnson
authors: Department of Endodontics, Arthur A. Dugoni School of Dentistry, University of the Pacific, San Francisco, California.
authors: Ove A
authors: OA
authors: Peters
mesh_terms: D000465:Algorithms; D003722:Dental Alloys / Q000737:chemistry; D004867:Equipment Design; D004868:Equipment Failure; D006801:Humans; D008422:Materials Testing; D009532:Nickel / Q000737:chemistry; D018915:Root Canal Preparation / Q000295:instrumentation*; D012399:Rotation; D013314:Stress, Mechanical; D013499:Surface Properties; D016019:Survival Analysis; D013997:Time Factors; D014025:Titanium / Q000737:chemistry
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium
keywords: Instrument fracture; nickel-titanium rotary intruments