title: Effect of movement kinematics on the cyclic fatigue resistance of nickel-titanium instruments.
abstract: OBJECTIVE
  To compare the cyclic fatigue resistance of new generation OneShape and WaveOne instruments when used with different kinematics.
  
  
  METHODS
  An artificial canal, made of stainless steel with an inner diameter of 1.5 mm, a 60° angle of curvature and a curvature radius of 3 mm, was used for cyclic fatigue test of new generation OneShape and WaveOne instruments. Groups were as follows (n = 20): 150°-30°, 210°-30°, 360°-30° and continuous rotation. The time to fracture was recorded in seconds, and the data were analysed statistically using a two-way anova and LSD tests (P = 0.05).
  
  
  RESULTS
  Cyclic fatigue resistance was significantly affected by the movement kinematics (P < 0.001). The cyclic fatigue resistance of the new generation OneShape instruments increased significantly when operated in various reciprocation motions (150° CW-30° CCW, 210° CW-30° CCW and 360° CW-30° CCW) compared with the continuous rotation mode. New generation OneShape instruments had significantly more resistance to fracture under cyclic loading than WaveOne instruments (P < 0.001).
  
  
  CONCLUSIONS
  When using new generation OneShape and WaveOne instruments, all the reciprocating motions (150° CW-30° CCW, 210° CW-30° CCW and 360° CW-30° CCW) resulted in extended fatigue life when compared with continuous rotation.
authors: Department of Endodontics, Faculty of Dentistry, Ataturk University, Erzurum, Turkey.
authors: E
authors: http://orcid.org/0000-0002-8145-8763
authors: E
authors: Karataş
authors: Department of Endodontics, Faculty of Dentistry, Ataturk University, Erzurum, Turkey.
authors: H
authors: H
authors: Arslan
authors: Department of Endodontics, Faculty of Dentistry, Ataturk University, Erzurum, Turkey.
authors: M
authors: M
authors: Büker
authors: Department of Endodontics, Faculty of Dentistry, Ataturk University, Erzurum, Turkey.
authors: F
authors: F
authors: Seçkin
authors: Department of Endodontics, Faculty of Dentistry, Katip Çelebi University, İzmir, Turkey.
authors: I D
authors: ID
authors: Çapar
mesh_terms: D003762:Dental Instruments; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008422:Materials Testing; D009532:Nickel / Q000737:chemistry*; D012399:Rotation; D013193:Stainless Steel; D013314:Stress, Mechanical; D014025:Titanium / Q000737:chemistry*; D019415:Torque
chemical_list: C040654:titanium nickelide; D013193:Stainless Steel; D009532:Nickel; D014025:Titanium
keywords: continuous rotation; cyclic fatigue; kinematics; reciprocation