IMR Press / FBL / Volume 26 / Issue 12 / DOI: 10.52586/5040
Open Access Original Research
Influence of short-term cooling on the performance of superelastic and thermally-treated rotary NiTi files tested in dynamic cyclic fatigue model
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1 Department of Restorative Dentistry, Division of Endodontics, Riyadh Elm University, 13244 Riyadh, Saudi Arabia
*Correspondence:; (Ammar AbuMostafa)
These authors contributed equally.
Academic Editor: Gianrico Spagnuolo
Front. Biosci. (Landmark Ed) 2021, 26(12), 1464–1469;
Submitted: 21 August 2021 | Revised: 7 November 2021 | Accepted: 15 November 2021 | Published: 30 December 2021
(This article belongs to the Special Issue NiTi Rotary Instruments in Endodontics)
Copyright: © 2021 The Author(s). Published by BRI.
This is an open access article under the CC BY 4.0 license (

Aim: The purpose of the present study was to investigate the effects of various short-term cooling durations on the performance of both superelastic and thermally treated nickel titanium (NiTi) files, tested in a dynamic cyclic fatigue model. Methodology: Superelastic RaCe (FKG, La Chaux-de-Fonds, Switzerland) and thermally treated RaCe EVO (FKG, La Chaux-de-Fonds, Switzerland) files of the same size and taper (25, 0.06) (n = 45 each) were tested using a dynamic cyclic fatigue model, where the number of cycles to failure (Nf) was measured at simulated body temperature. In each group, the samples were tested as received, after 5 seconds of cooling treatment, and after 15 seconds of cooling treatment (n = 15 each). Fractured file surfaces were investigated via scanning electron microscopy. Statistical analysis was performed using a one-way ANOVA with Scheffe’s post hoc test at a significance level of 0.05. Results: Significant differences in the Nf between the tested groups were found (p < 0.05) at each testing condition, where RaCe Evo files showed overall improved cyclic fatigue resistance. Only the RaCe groups at 5 second cooling showed significantly higher Nf than the control subgroup (p < 0.05). RaCe EVO group, showed no significant difference between the 3 subgroups (p > 0.05). Scanning Electron Microscope (SEM) images revealed typical features of cyclic fatigue behavior in both groups. Conclusions: Short-term cooling application for 5 seconds on superelastic NiTi files showed an enhanced cyclic fatigue resistance.

Dynamic cyclic fatigue
NiTi file
Fig. 1.
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