title: Blue treatment enhances cyclic fatigue resistance of vortex nickel-titanium rotary files.
abstract: BACKGROUND
  The aim of the present study was to evaluate the difference in cyclic fatigue resistance between Vortex Blue (Dentsply Tulsa Dental, Tulsa, OK) and Profile Vortex nickel-titanium (Dentsply Tulsa Dental) rotary instruments.
  
  
  METHODS
  Two groups of nickel-titanium endodontic instruments, ProFile Vortex and Vortex Blue, consisting of identical instruments in tip size and taper (15/.04, 20/.06, 25/.04, 25/.06, 30/.06, 35/.06, and 40/.04) were tested. Ten instruments from each system and size were tested for cyclic fatigue resistance, resulting in a total of 140 new instruments. All instruments were rotated in a simulated root canal with a 60° angle of curvature and a 5-mm radius of curvature of a specific cyclic fatigue testing device until fracture occurred. The number of cycles to failure and the length of the fractured tip were recorded for each instrument in each group. The mean values and standard deviation were calculated, and data were subjected to 1-way analysis of variance and a Bonferroni t test. Significance was set at the 95% confidence level.
  
  
  RESULTS
  When comparing the same size of the 2 different instruments, a statistically significant difference (P < .05) was noted between all sizes of Vortex Blue and Profile Vortex instruments except for tip size 15 and .04 taper (P = 1.000). No statistically significant difference (P > .05) was noted among all groups tested in terms of fragment length.
  
  
  CONCLUSIONS
  Vortex Blue showed a significant increase in cyclic fatigue resistance when compared with the same sizes of ProFile Vortex.
authors.affiliation: Department of Endodontics, "Sapienza" University of Rome, Rome, Italy. Electronic address: endo@gianlucaplotino.com.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Plotino
authors.affiliation: Department of Endodontics, "Sapienza" University of Rome, Rome, Italy.
authors.forename: Nicola M
authors.initials: NM
authors.lastname: Grande
authors.affiliation: Department of Endodontics, University of Cagliari, Cagliari, Italy.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Cotti
authors.affiliation: Department of Endodontics, "Sapienza" University of Rome, Rome, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Testarelli
authors.affiliation: Department of Endodontics, "Sapienza" University of Rome, Rome, Italy.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Gambarini
mesh_terms: D003722:Dental Alloys / Q000737:chemistry*; D004867:Equipment Design; D004868:Equipment Failure; D006801:Humans; D008422:Materials Testing; D009532:Nickel / Q000737:chemistry*; D018915:Root Canal Preparation / Q000295:instrumentation*; D012399:Rotation; D013314:Stress, Mechanical; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*; D019415:Torque
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium
keywords: Cyclic fatigue resistance; metal treatment; nickel-titanium instruments