title: Comparison of the Resistance of Teeth Instrumented with Different Nickel-Titanium Systems to Vertical Root Fracture: An In Vitro Study.
abstract: BACKGROUND
  This study compared the fracture resistance of teeth instrumented with ProTaper Universal (Dentsply Maillefer, Ballaigues, Switzerland), ProTaper Next (PTN, Dentsply Maillefer), WaveOne (Dentsply Maillefer), Twisted File (SybronEndo, Orange, CA), Mtwo (MT; VDW, München, Germany), and Revo-S (MicroMega, Besançon, France) nickel-titanium systems and obturated with compatible gutta-percha cones of finishing files using the single-cone technique and a resin sealer.
  
  
  METHODS
  The study included 72 mandibular premolar teeth. The roots were covered with additive silicone and placed in Eppendorf tubes, which were filled with a self-curing acrylic. The tubes were separated into 6 groups: prepared with the ProTaper Universal (F4 40/.06) (group 1), prepared with the PTN (X4 40/.06) (group 2), prepared with the WaveOne reciprocating file (40/.08) (group 3), prepared with the Twisted File (40/.04) (group 4), prepared with the MT (40/.06) (group 5), and prepared with the Revo-S (AS 40/.06) (group 6). After the preparations were completed, all the teeth were filled with the appropriate gutta-percha systems. The force (N) was applied at a 1-mm/min crosshead speed until the roots fractured. Differences among the groups were analyzed by Tukey and analysis of variance tests.
  
  
  RESULTS
  Group 2 was the most resistant to fracture, and group 5 was the least resistant. The difference in the fracture resistance between the 2 groups was statistically significant (P = .019). The resistance of group 3 and group 6 to vertical root fracture was similar, and the resistance of group 4 was slightly lower than that of the other groups (P = .058).
  
  
  CONCLUSIONS
  The roots instrumented with the MT were the least resistant, and the roots instrumented with the PTN were the most resistant to VRF.
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Bülent Ecevit University, Zonguldak, Turkey. Electronic address: ersancicek@beun.edu.tr.
authors.forename: Ersan
authors.initials: E
authors.lastname: Çiçek
authors.affiliation: Department of Prosthodontics, Faculty of Dentistry, Abant Izzet Baysal University, Bolu, Turkey.
authors.forename: M Ali
authors.initials: MA
authors.lastname: Aslan
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Bülent Ecevit University, Zonguldak, Turkey.
authors.forename: Oğuzhan
authors.initials: O
authors.lastname: Akkoçan
mesh_terms: D000293:Adolescent; D001641:Bicuspid / Q000293:injuries; D003722:Dental Alloys; D003799:Dental Stress Analysis; D006171:Gutta-Percha / Q000627:therapeutic use; D006801:Humans; D066298:In Vitro Techniques; D008334:Mandible; D009532:Nickel; D012389:Root Canal Obturation / Q000379:methods*; D018915:Root Canal Preparation / Q000295:instrumentation* / Q000379:methods; D014025:Titanium; D014082:Tooth Fractures / Q000517:prevention & control*; D014092:Tooth Root / Q000293:injuries*; D055815:Young Adult
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D006171:Gutta-Percha; D014025:Titanium
keywords: Fracture resistance; in vitro study; nickel-titanium systems; vertical root fracture