title: Comparative evaluation of cyclic fatigue resistance of four different nickel-titanium rotary files with different cross-sectional designs and alloy properties.
abstract: OBJECTIVE
  The purpose of the present study was to evaluate the cyclic fatigue resistance of F6 SkyTaper (Komet Brasseler, Lemgo, Germany), K3XF (SybronEndo, Orange, CA, USA), new generation OneShape (Micro Mega, Besancon, France) and TRUShape 3D conforming files (Dentsply Tulsa Dental Specialties, Tulsa, OK, USA).
  
  
  METHODS
  Ten instruments from each group were selected and allowed to rotate using a low-torque motor in a stainless steel block with 1.5 mm diameter, 3 mm radius of 60° angle of curvature at the manufacturer's recommended speed, and the number of cycles (NCF) from the beginning to the fracture was recorded. The data were analyzed using one-way ANOVA followed by post-hoc Tukey's test (P = 0.05).
  
  
  RESULTS
  The ranking of the groups from the highest to the lowest NCF was as follows: F6 SkyTaper (959 ± 92), K3XF (725 ± 71), TRUShape (575 ± 84) and OneShape (289 ± 58). Statistically significant differences were detected between all groups (P < 0.05).
  
  
  CONCLUSIONS
  Within the limitations of this study, F6 SkyTaper instruments presented the highest cyclic fatigue resistance among the tested instruments. The S-shaped cross-sectional design of F6 SkyTaper instruments could be the most important factor on the superior cyclic life span of these instruments.
  
  
  CONCLUSIONS
  In endodontic practice, preferring the instruments with higher cyclic fatigue resistance would help to minimize the risk of instrument fractures; therefore especially during the preparation of curved canals, instruments with smaller core area and less cross-sectional metal mass, which could lead higher flexibility, can be proposed.
authors.affiliation: Department of Endodontology, School of Dentistry, Ege University, Bornova, Izmir, Turkey. mehmetkaval@hotmail.com.
authors.forename: Mehmet Emin
authors.initials: ME
authors.lastname: Kaval
authors.affiliation: Department of Endodontology, School of Dentistry, Katip Çelebi University, Izmir, Turkey.
authors.forename: Ismail Davut
authors.initials: ID
authors.lastname: Capar
authors.affiliation: Department of Endodontology, School of Dentistry, Katip Çelebi University, Izmir, Turkey.
authors.forename: Hüseyin
authors.initials: H
authors.lastname: Ertas
authors.affiliation: Private clinic, Izmir, Turkey.
authors.forename: Bilge Hakan
authors.initials: BH
authors.lastname: Sen
mesh_terms: D003722:Dental Alloys / Q000737:chemistry*; D003762:Dental Instruments; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008422:Materials Testing; D009532:Nickel / Q000737:chemistry*; D018915:Root Canal Preparation / Q000295:instrumentation*; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*; D019415:Torque
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium
keywords: Cyclic fatigue; F6 SkyTaper; K3XF; OneShape; TRUShape 3D conforming files