Comparative Evaluation of Resistance to Cyclic Fatigue of Three Rotary Endodontic Ni-Ti Instruments

Lampros Intzes 1 , Zoi-Despoina Tzima 1  and Christos Gogos 1
  • 1 Department of Endodontology, School of Dentistry, Aristotle University of Thessaloniki, Thessaloniki, Greece


Background/Aim: The present study examined the resistance to cyclic fatigue of three different rotary Ni-Ti instruments: K3XF (Kerr, Orange, CA), HyFlex CM (Coltene/Whaledent, Altstätten, Switzerland) and X7 EdgeFile (EdgeEndo, Albuquerque, New Mexico).

Material and Methods: Thirty instruments (n=30) of each type were used with tip size 25 and 0.04 taper. All instruments were constrained to 600 of curvature with a radius of 5 mm by the use of two grooved stainless steel rods and rotated at a speed of 300 rpm and 3.0 Ncm of torque. The time until separation was recorded for each of the instruments and the number of cycles to fracture (NCF) was calculated. Statistical analysis was performed using R Programming language.

Results: The X7 EdgeFile instrument showed significantly greater resistance to cyclic fatigue when compared to the HyFlex CM and the K3XF with mean NCF for each instrument 1046 ± 311, 707 ± 219 and 360 ± 96 respectively. HyFlex CM performed significantly better than K3XF.

Conclusions: The X7 EdgeFile Ni-Ti file appears to be significantly more resistant to fracture, due to flexural fatigue, than the HyFlex CM and the K3XF.

If the inline PDF is not rendering correctly, you can download the PDF file here.

  • 1. Hülsmann M, Peters OA, Dummer PMH: Mechanical preparation of root canals: shaping goals, techniques and means. Endod Topics, 2005;10:30-76.

  • 2. Serene TP, Adams JD, Saxena A. Nickel-titanium instruments: applications in endodontics. St Louis, MO, USA: Ishiyaku EuroAmerica, 1995.

  • 3. Sattapan B, Palamara J, Messer H. Torque during canal instrumentation using rotary nickel-titanium files. J Endod, 2000;26:156-160.

  • 4. Phillips R. Skinner’s science of dental materials. Philadelphia: WB Saunders Co., 1991.

  • 5. Peters OA. Current challenges and concepts in the preparation of root canal systems: a review. J Endod, 2004;30:559-567.

  • 6. Parashos P, Messer H. Rotary NiTi instrument fracture and its consequences. J Endod, 2006;32:1031-1043.

  • 7. Plotino G, Costanzo A, Grande NM, Petrovic R, Testarelli L, Gambarini G. Experimental evaluation on the influence of autoclave sterilization on the cyclic fatigue of new Nickel-Titanium rotary instruments. J Endod, 2012;38:222-225.

  • 8. Ha JH, Kim SK, Cohenca N, Kim HC. Effect of R-phase heat treatment on torsional resistance and cyclic fatigue fracture. J Endod, 2013;39:389-393.

  • 9. Duerig TW, Bhattacharya K. The influence of the R-Phase on the superelastic behavior of NiTi. Shap Mem Superelast, 2015;1:153-161.

  • 10. Lopes HP, Gambarra-Soares T, Elias CN, Siqueira JF Jr, Inojosa IF, Lopes WS, et al. Comparison of the mechanical properties of rotary instruments made of conventional Nickel-Titanium wire, M-wire, or Nickel-Titanium alloy in R-phase. J Endod, 2013;39:516-520.

  • 11. Shen Y, Qien W, Abtin H, Gao Y, Haapasalo M. Fatigue testing of controlled memory wire nickel-titanium rotary instruments. J Endod, 2011;37:997-100.

  • 12. Zhao D, Shen Y, Peng B, Haapasalo M. Micro-computed tomography evaluation of the preparation of mesiobuccal root canals in maxillary first molars with Hyflex CM, Twisted Files, and K3 instruments. J Endod, 2013;39:385-388.

  • 13. Plotino G, Testraelli L, Al-Sudani D, Pongione G, Grande NM, Gambarini G. Fatigue resistance of rotary instruments manufactured using different nickel-titanium alloys: a comparative study. Odontology, 2014;102:31-35.

  • 14. Peters OA, Gluskin AK, Weiss RA, Han JT. An in vitro assessment of the physical properties of novel Hyflex nickel-titanium rotary instruments. Int Endod J, 2012;11:1027-1034.

  • 15. Alfoqom Alazemi M, Bryant ST, Dummer PMH. Deformation of Hyflex CM instruments and their shape recovery following heat sterilization. Int Endod J, 2015;48:593-601.

  • 16. Pruett JP, Clement DJ, Carnes DL Jr. Cyclic fatigue testing of Nickel-Titanium endodontic instruments. J Endod, 1997;23:77-85.

  • 17. Plotino G, Grande NM, Cordaro M, Testarelli L, Gambarini G. A review of cyclic fatigue testing of Nickel-Titanium rotary instruments. J Endod, 2009;35:1469-1476.

  • 18. Zinelis S, Darabara M, Takase T, Ogane K, Papadimitriou GD. The effect of thermal treatment on the resistance of nickel-titanium rotary files. Oral Surg Oral Med Oral Pathol Oral Radiol Endod, 2007;103:843-847.

  • 19. Anderson ME, Price JWH, Parashos P. Fracture resistance of electropolished rotary nickel-titanium endodontic instruments. J Endod, 2007;33:1212-1216.

  • 20. Ounsi HF, Salameh Z, Al-Shalan T, Ferrari M, Grandini S, Pashley DH, et al. Effect of clinical use on the cyclic fatigue resistance of ProTaper nickel-titanium rotary instruments. J Endod, 2007;33:737-741.

  • 21. Plotino G, Grande NM, Cordaro M, Testarelli L, Gambarini G. Influence of the shape of artificial canals on the fatigue resistance of NiTi rotary instruments. Int Endod J, 2010;43:69-75.

  • 22. Perez-Higueras JJ, Arias A, Macorra JC. Cyclic fatigue resistance of K3, K3XF, and Twisted File Nickel-Titanium files under continuous rotation or reciprocating motion. J Endod, 2013;39:1585-1588.

  • 23. Ninan E, Berzins DW. Torsion and bending properties of shape memory and superelastic nickel-titanium rotary instruments. J Endod, 2013;39:101-104.

  • 24. Zhou H, Peng B, Zheng YF. An overview of the mechanical properties of nickel–titanium endodontic instruments. Endod Topics, 2013;29:42-54.


Journal + Issues