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Fatigue and nanomechanical properties of K3 XF nickel‐titanium instruments
Author(s) -
Shen Y.,
Zhou H.,
Campbell L.,
Wang Z.,
Wang R.,
Du T.,
Haapasalo M.
Publication year - 2014
Publication title -
international endodontic journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.988
H-Index - 119
eISSN - 1365-2591
pISSN - 0143-2885
DOI - 10.1111/iej.12265
Subject(s) - nanoindentation , materials science , nickel titanium , scanning electron microscope , composite material , dimple , cyclic stress , modulus , elastic modulus , fracture (geology) , shape memory alloy
Aim To examine the fatigue behaviour of heat‐treated NiTi instruments when immersed in aqueous media and to determine the effect of cyclic fatigue on the hardness and elastic modulus of NiTi instruments using a nanoindentation technique. Methodology K3 XF and K3 NiTi instruments, both in sizes 25, 0.04 taper and 40, 0.04 taper, were subjected to rotational bending at a curvature of 42° either in air or under deionized water, and the number of revolutions to fracture ( N f ) was recorded. The fracture surface of all fragments was examined with a scanning electron microscope. The hardness and elastic modulus of the fracture surface of instruments sized 25, 0.04 taper were then measured using a nanoindentation test. Results The K3 XF instruments had a fatigue resistance superior to K3 instruments under dry and aqueous environments ( P < 0.05). The fatigue life of K3 instruments was similar under both conditions, whereas the N f of K3 XF was greater under water than in air, especially at the size 40, 0.04 taper ( P < 0.05). The values for the fraction of the area occupied by the dimple region were significantly smaller in K3 XF instruments than in K3 instruments, especially under water ( P < 0.05). There was no difference in hardness on K3 XF instruments between new files and instruments subjected to the fatigue process. The hardness of instruments subjected to the fatigue process was significantly lower in K3 XF than in K3 instruments ( P < 0.05). Conclusion The fatigue life of K3 XF instruments under water is longer than it is for K3 XF instruments in air. There was no work‐hardening effect on K3 XF instruments subjected to the fatigue process.