Multiple autoclave cycle effects on cyclic fatigue of nickel-titanium rotary files produced by new manufacturing methods

Paul B. Hilfer, Brian E. Bergeron, Michael J. Mayerchak, Howard W. Roberts, Billie G. Jeansonne

Research output: Contribution to journalArticlepeer-review

48 Scopus citations


Introduction: Novel nickel-titanium rotary files with proprietary manufacturing techniques have recently been marketed. The purpose of this study was to assess multiple autoclave cycle effects on cyclic fatigue of GT Series X files (Dentsply Tulsa Dental Specialties, Tulsa, OK) and Twisted Files (SybronEndo, Orange, CA) Methods: A jig using a 5-mm radius curve with 90° of maximum file flexure was used to induce cyclic fatigue failure. Files (n = 10) representing each experimental group (GT Series X 20/.04 and 20/.06; Twisted Files 25/.04 and 25/.06) were first tested to establish baseline mean cycles to failure (MCF). Experimental groups (n = 20) were then cycled to 25% of the established baseline MCF and then autoclaved. Additional autoclaving was accomplished at 50% and 75% of MCF followed by continual testing until failure. Control groups (n = 20) underwent the same procedures except autoclaving was not accomplished. Results: The GT Series X (20/.04 and 20/.06) files showed no significant difference (p = 0.918/p = 0.096) in MCF for experimental versus control files. Twisted Files (25/.04) showed no significant difference (p = 0.432) in MCF between experimental and control groups. However, the Twisted Files (25/.06) experimental group showed a significantly lower (p = 0.0175) MCF compared with the controls. Conclusions: Under the conditions of this evaluation, autoclave sterilization significantly decreased cyclic fatigue resistance of one of the four file groups tested. Repeated autoclaving significantly reduced the MCF of 25/.06 Twisted Files; however, 25/.04 Twisted Files and both GT Series X files tested were not significantly affected by the same conditions.

Original languageEnglish
Pages (from-to)72-74
Number of pages3
JournalJournal of Endodontics
Issue number1
StatePublished - Jan 2011

Bibliographical note

Funding Information:
Supported by the AAE Foundation .


  • Autoclave
  • cyclic fatigue
  • nickel-titanium

ASJC Scopus subject areas

  • General Dentistry


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