title: Comparison of the cyclic fatigue resistance of 5 different rotary pathfinding instruments made of conventional nickel-titanium wire, M-wire, and controlled memory wire.
abstract: BACKGROUND
  This study compared the cyclic fatigue resistance of current nickel-titanium rotary path-finding instruments.
  
  
  METHODS
  Five types of nickel-titanium rotary pathfinding instruments were used in steel canals with a 90° curvature and a curvature radius of 3 mm (n = 10) and 5 mm (n = 10). The cyclic fatigue of the following instruments was tested at 4 mm from the tip: PathFile (#16 and a .02 taper; Dentsply Maillefer, Ballaigues, Switzerland), G-File (#12 and a .03 taper; Micro-Mega, Besançon Cedex, France), Scout Race (#15 and a .02 taper; FKG Dentaire, La Chaux-de-Fonds, Switzerland), HyFlex GPF (#15 and a .02 taper; Coltene-Whaledent, Allstetten, Switzerland), and ProGlider (#16 with a mean taper of .04125 and a .02 at the first 4 mm from the tip, Dentsply Maillefer). The length of the fractured parts was measured, and the number of cycles to fracture (NCF) was calculated. The data were statistically analyzed using Kruskal-Wallis and Mann-Whitney tests (α = .05). After Bonferroni correction, the new P value was set as .005.
  
  
  RESULTS
  The difference in the cyclic fatigue of all the files at both curvatures was statistically significant (P values from .0035 to less than .0001). The ranking of the instruments from the highest to the lowest NCF was as follows: HyFlex GPF, G files, ProGlider, PathFile, and Scout Race. The length of the fractured part of the instruments was similar in all the groups (P > .05). All the tested instruments had a lower NCF at a curvature radius of 3 mm when compared with a curvature radius of 5 mm (P < .0001).
  
  
  CONCLUSIONS
  Within the limitations of this study, the cyclic fatigue resistance of the HyFlex GPF instrument was the highest, and the curvature radius had a significant effect on the fatigue resistance.
authors.affiliation: Department of Endodontics, Faculty of Dentistry, İzmir Katip Çelebi University, İzmir, Turkey. Electronic address: capardt@hotmail.com.
authors.forename: Ismail Davut
authors.initials: ID
authors.lastname: Capar
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Ege University, İzmir, Turkey.
authors.forename: Mehmet Emin
authors.initials: ME
authors.lastname: Kaval
authors.affiliation: Department of Endodontics, Faculty of Dentistry, İzmir Katip Çelebi University, İzmir, Turkey.
authors.forename: Hüseyin
authors.initials: H
authors.lastname: Ertas
authors.affiliation: Department of Endodontics, Faculty of Dentistry, İzmir Katip Çelebi University, İzmir, Turkey.
authors.forename: Bilge Hakan
authors.initials: BH
authors.lastname: Sen
mesh_terms: D003762:Dental Instruments; D004868:Equipment Failure; D008422:Materials Testing; D009532:Nickel; D014025:Titanium; D054159:Torsion, Mechanical
chemical_list: C040654:titanium nickelide; D009532:Nickel; D014025:Titanium
keywords: Cyclic fatigue; G-File; HyFlex GPF; PathFile; ProGlider; Scout Race; endodontics; glide path; nickel-titanium rotary instruments