title: Variations in cyclic fatigue resistance among ProTaper Gold, ProTaper Next and ProTaper Universal instruments at different levels.
abstract: OBJECTIVE
  To compare the cyclic fatigue resistance of ProTaper Gold (PTG, Dentsply Tulsa Dental Specialities, Tulsa, OK, USA), ProTaper Next (PTN, Dentsply Tulsa Dental Specialities) and ProTaper Universal (PTU, Dentsply Tulsa Dental Specialities) instruments at different levels.
  
  
  METHODS
  A total of 72 files were used to evaluate the cyclic fatigue of PTU (F2), PTN (X2) and PTG (F2) at 5 mm (n = 12) and 8 mm (n = 12) from the tip in 3-mm-radius steel canals with a 60° angle of curvature. The time to fracture was recorded. The Kolmogorov-Smirnov test was used to assess the normality of the samples distribution, and the statistical analysis was performed using the independent sample t-test (P < 0.01).
  
  
  RESULTS
  Significant differences were found amongst the instruments 5 mm from the tip (P < 0.01). The PTG files had the highest CF resistance, and the PTN files displayed greater CF resistance than the PTU files. No significant differences were found between the PTG and PTN files 8 mm from the tip (P > 0.01). The PTG and PTN files demonstrated greater CF resistance than the PTU files (P < 0.01).
  
  
  CONCLUSIONS
  The PTG instruments were the most resistant 5 and 8 mm from the tip; however, at 8 mm, there was no difference between the PTG and PTN instruments. The PTU files had the lowest CF resistance at all levels.
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Ataturk University, Erzurum, Turkey.
authors.forename: A D
authors.initials: AD
authors.lastname: Uygun
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Ataturk University, Erzurum, Turkey.
authors.forename: E
authors.initials: E
authors.lastname: Kol
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Ataturk University, Erzurum, Turkey.
authors.forename: M K C
authors.initials: MK
authors.lastname: Topcu
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Ataturk University, Erzurum, Turkey.
authors.forename: F
authors.initials: F
authors.lastname: Seckin
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Sifa University, Izmir, Turkey.
authors.forename: I
authors.initials: I
authors.lastname: Ersoy
authors.affiliation: Department of Pedodontics, Faculty of Dentistry, Sifa University, Izmir, Turkey.
authors.forename: M
authors.initials: M
authors.lastname: Tanriver
mesh_terms: D004868:Equipment Failure; D006046:Gold; D006801:Humans; D009532:Nickel; D018915:Root Canal Preparation; D014025:Titanium
chemical_list: D006046:Gold; D009532:Nickel; D014025:Titanium
keywords: ProTaper Gold; ProTaper Next; ProTaper Universal; cyclic fatigue; rotary instrument