Torsion Property and Cyclic Fatigue Fracture Behavior of Nickel-Titanium Endodontic Instruments


Article Preview

The torsion property and rotary fatigue fracture behavior of SmartÒ K file and R reamer made of nickel titanium alloy have been studied by means of Shimadzu Autograph DDS-10T universal tester and man-made cyclic system with curved copper tubes as simulated root canal. The instrument surface and the cyclic fatigue fracture surface have been investigated by optical microscope and scanning electron microscope. Comparing with ANSI/ADA specification no.28, maximum torsion values of both SmartÒ K and R endodontic instruments are satisfied in practice. Tensile stresses on the outer surface of the endodontic instruments play a dominant role in fracture initiation during cyclic fatigue fracture. The cyclic number corresponding to cyclic fatigue fracture decreases with the increase of the instrument size number/ curvature. SmartÒ K- and R endodontic instruments exhibit good ductility characteristics, therefore superior resistance to fracture.



Key Engineering Materials (Volumes 288-289)

Edited by:

Xingdong Zhang, Junzo Tanaka, Yaoting Yu and Yasuhiko Tabata




Y. F. Zheng et al., "Torsion Property and Cyclic Fatigue Fracture Behavior of Nickel-Titanium Endodontic Instruments", Key Engineering Materials, Vols. 288-289, pp. 603-606, 2005

Online since:

June 2005




[1] J.P. Pruett, D. J. Clement and D.L. Carnes: Journal of Endodontics, Vol. 23 (1997), p.77.

[2] Y. Haikel, R. serfaty and C. Allemann: Journal of Endodontics Vol. 25 (1999), p.434.

[3] Y.F. Zheng and B.M. Huang: Chinese patent No. 00130007. 5.

[4] Y.F. Zheng, B.M. Huang, M. Li and Y. Sui: Chinese patent No. 01260828. 9.