title: Cyclic fatigue resistance of 3 different nickel-titanium reciprocating instruments in artificial canals.
abstract: BACKGROUND
  The purpose of this study was to evaluate the cyclic fatigue resistance of 3 different nickel-titanium reciprocating instruments.
  
  
  METHODS
  A total of 45 nickel-titanium instruments were tested and divided into 3 experimental groups (n = 15): group 1, WaveOne Primary instruments; group 2, Reciproc R25 instruments; and group 3, Twisted File (TF) Adaptive M-L1 instruments. The instruments were then subjected to cyclic fatigue test on a static model consisting of a metal block with a simulated canal with 60° angle of curvature and a 5-mm radius of curvature. WaveOne Primary, Reciproc R25, and TF Adaptive instruments were activated by using their proprietary movements, WaveOne ALL, Reciproc ALL, and TF Adaptive, respectively. All instruments were activated until fracture occurred, and the time to fracture was recorded visually for each file with a 1/100-second chronometer. Mean number of cycles to failure and standard deviations were calculated for each group, and data were statistically analyzed (P < .05). Instruments were also observed through scanning electron microscopy to evaluate type of fracture.
  
  
  RESULTS
  Cyclic fatigue resistance of Reciproc R25 and TF Adaptive M-L1 was significantly higher than that of WaveOne Primary (P = .009 and P = .002, respectively). The results showed no statistically significant difference between TF Adaptive M-L1 and Reciproc R25 (P = .686). Analysis of the fractured portion under scanning electron microscopy indicated that all instruments showed morphologic characteristics of ductile fracture that were due to accumulation of metal fatigue.
  
  
  CONCLUSIONS
  No statistically significant differences were found between the instruments tested except for WaveOne Primary, which showed the lowest resistance to cyclic fatigue.
authors.affiliation: Department of Endodontics, Universidad Autonoma de Baja California, Tijuana, Mexico.
authors.forename: Oscar
authors.initials: O
authors.lastname: Higuera
authors.affiliation: Department of Endodontics, "Sapienza"-University of Rome, Rome, Italy.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Plotino
authors.affiliation: Department of Endodontics, "Sapienza"-University of Rome, Rome, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Tocci
authors.affiliation: Department of Endodontics, Universidad Autonoma de Baja California, Tijuana, Mexico.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Carrillo
authors.affiliation: Department of Endodontics, "Sapienza"-University of Rome, Rome, Italy.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Gambarini
authors.affiliation: Department of Endodontics, School of Dentistry, University of Texas Health Science Center at Houston, Houston, Texas. Electronic address: David.E.Jaramillo@uth.tmc.edu.
authors.forename: David E
authors.initials: DE
authors.lastname: Jaramillo
mesh_terms: D003722:Dental Alloys; D003799:Dental Stress Analysis; D004867:Equipment Design; D004868:Equipment Failure; D006801:Humans; D008422:Materials Testing; D009532:Nickel; D018915:Root Canal Preparation / Q000295:instrumentation*; D013314:Stress, Mechanical; D014025:Titanium
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium
keywords: Cyclic fatigue; NiTi instruments; cyclic fatigue test; reciprocation