title: Cyclic fatigue resistance of two reciprocating nickel-titanium instruments after immersion in sodium hypochlorite.
abstract: OBJECTIVE
  To assess resistance to cyclic fatigue of reciprocating nickel-titanium ( NiTi ) files (Reciproc and WaveOne) after immersion in NaOCl solution over several time periods.
  
  
  METHODS
  A total of 90 new Reciproc R25 and WaveOne Primary were tested. The 45 files of the same brand were randomly assigned to three groups (n = 15) and submitted to the following immersion protocol in 5% NaOCl at 37 °C for 16 mm: no immersion (control), 1 or 5 min dynamically. The dynamic immersion and the following cyclic fatigue tests were performed using the appropriate preset reciprocation modes ('RECIPROC ALL' or 'WAVEONE ALL') in a specially designed endodontic motor. Resistance to cyclic fatigue was determined by recording time to fracture (TtF) in a stainless steel artificial canal with a 60° angle of curvature and 5 mm radius of curvature. The artificial canal was manufactured reproducing the instrument's size and taper. Data were analysed by 2-way analyses of variance.
  
  
  RESULTS
  Resistance to cyclic fatigue of the same NiTi file was not significantly affected by immersion in NaOCl . Reciproc R25 was associated with a higher cyclic fatigue resistance in all groups compared to WaveOne Primary (P < 0.0001).
  
  
  CONCLUSIONS
  Reciprocating dynamic immersion in NaOCl for 1 or 5 min did not reduce the cyclic fatigue resistance of NiTi files significantly. However, the type of reciprocating instrument influenced cyclic fatigue resistance with Reciproc R25 being more resistant than WaveOne Primary.
authors: Department of Surgery, University of Catania, Catania, Italy. eugeniopedulla@gmail.com
authors: E
authors: E
authors: Pedullà
authors: N M
authors: NM
authors: Grande
authors: G
authors: G
authors: Plotino
authors: F
authors: F
authors: Palermo
authors: G
authors: G
authors: Gambarini
authors: E
authors: E
authors: Rapisarda
mesh_terms: D003722:Dental Alloys; D019551:Dental Disinfectants; D003762:Dental Instruments; D003799:Dental Stress Analysis; D004867:Equipment Design; D004868:Equipment Failure; D007101:Immersion; D008422:Materials Testing; D009532:Nickel; D011897:Random Allocation; D018915:Root Canal Preparation / Q000295:instrumentation*; D012973:Sodium Hypochlorite; D014025:Titanium
chemical_list: D003722:Dental Alloys; D019551:Dental Disinfectants; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium; D012973:Sodium Hypochlorite