title: The effects of dentin debris on the cyclic fatigue resistance of several nickel titanium rotary systems.
abstract: OBJECTIVE
  The aim of this study was to compare the effects of impacted dentin debris on the cyclic fatigue resistance of a traditional ground file, an electropolished file, and a thermally treated twisted file.
  
  
  METHODS
  One hundred thirty-five files were rotated against bovine dentin or a highly polished surface at the manufacturers' recommended rotation speed with a continuous 5-mm axial movement of 1 cycle per second. The files were equally divided into 3 groups: group 1, contacting dentin for 500 cycles and then metal to failure; group 2, contacting metal only to failure; group 3, contacting dentin only to failure. Cycles to failure were analyzed using analysis of variance (P < .05).
  
  
  RESULTS
  K3 and Twisted Files outperformed EndoSequence files in the dentin-only group. No difference was found between the metal and dentin-metal groups.
  
  
  CONCLUSIONS
  In the presence of dentin, the electropolished surface of the EndoSequence NiTi rotary files did not increase the files' cyclic fatigue resistance compared with K3 or Twisted Files of the same tip size and taper.
authors.affiliation: Department of Endodontics, Wilford Hall Medical Center, Lackland AFB, TX 78236, USA.
authors.forename: James A
authors.initials: JA
authors.lastname: Wealleans
authors.forename: Timothy C
authors.initials: TC
authors.lastname: Kirkpatrick
authors.forename: Richard E
authors.initials: RE
authors.lastname: Rutledge
mesh_terms: D000818:Animals; D002417:Cattle; D003762:Dental Instruments; D003799:Dental Stress Analysis; D003804:Dentin; D004867:Equipment Design; D004868:Equipment Failure; D017743:Equipment Reuse; D009532:Nickel; D018915:Root Canal Preparation / Q000295:instrumentation*; D016369:Smear Layer; D013499:Surface Properties; D014025:Titanium
chemical_list: C040654:titanium nickelide; D009532:Nickel; D014025:Titanium