title: Cyclic fatigue and torsional resistance of two new nickel-titanium instruments used in reciprocation motion: Reciproc versus WaveOne.
abstract: BACKGROUND
  The use of reciprocating movement was claimed to increase the resistance of nickel-titanium (NiTi) file to fatigue in comparison with continuous rotation. Recently 2 new brands of NiTi files have been marketed for use in a RM mode. The purpose of this study was to compare the cyclic fatigue resistance and torsional resistance of these 2 files, Reciproc and WaveOne.
  
  
  METHODS
  Cyclic fatigue test with a simultaneous pecking motion was performed with the instrument (n = 10 each) operating in the recommended reciprocation motion until fracture for the Reciproc R25 and WaveOne Primary files. ProTaper F2 was tested in continuous rotation to serve as a control for comparison. The number of cycles to fracture (NCF) was determined by measuring the time to fracture. The length of the fragment was measured and the fracture surface was examined by using scanning electron microscopy. Torsional strength was measured by using a torsiometer after fixing the apical 5 mm of the instrument rigidly. Statistical analysis was performed by using one-way analysis of variance.
  
  
  RESULTS
  The results showed that Reciproc had a higher NCF and WaveOne had a higher torsional resistance than the others. Both reciprocating files demonstrated significantly higher cyclic fatigue and torsional resistances than ProTaper (P < .05). The fractographic analysis showed typical features of cyclic fatigue and torsional failure for all instruments.
  
  
  CONCLUSIONS
  The 2 brands of NiTi file for use with a reciprocation motion seem to have superior mechanical properties.
authors.affiliation: Department of Conservative Dentistry, School of Dentistry, Pusan National University, Yangsan, Korea.
authors.forename: Hyeon-Cheol
authors.initials: HC
authors.lastname: Kim
authors.forename: Sang-Won
authors.initials: SW
authors.lastname: Kwak
authors.forename: Gary Shun-Pan
authors.initials: GS
authors.lastname: Cheung
authors.forename: Dae-Hoon
authors.initials: DH
authors.lastname: Ko
authors.forename: Se-Min
authors.initials: SM
authors.lastname: Chung
authors.forename: WooCheol
authors.initials: W
authors.lastname: Lee
mesh_terms: D003722:Dental Alloys / Q000737:chemistry*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D008855:Microscopy, Electron, Scanning; D009068:Movement; D009532:Nickel / Q000737:chemistry*; D018583:Pliability; D018915:Root Canal Preparation / Q000295:instrumentation*; D012399:Rotation; D013314:Stress, Mechanical; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*; D054159:Torsion, Mechanical
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium