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Comparative Study
. 2020 Feb 4;20(1):38.
doi: 10.1186/s12903-020-1027-7.

In vitro comparison of cyclic fatigue resistance of TruNatomy in single and double curvature canals compared with different nickel-titanium rotary instruments

Amr M Elnaghy  1 , Shaymaa E Elsaka  2   3 , Ayman O Mandorah  4
Affiliations
Comparative Study

In vitro comparison of cyclic fatigue resistance of TruNatomy in single and double curvature canals compared with different nickel-titanium rotary instruments

Amr M Elnaghy et al. BMC Oral Health. .

Abstract

Background: The purpose of this study was to compare the cyclic fatigue resistance of newly developed TruNatomy instruments (TRN) in single and double (S-shaped) curvature canals with HyFlex CM (HCM), Vortex Blue (VB) and RaCe (RC) instruments.

Methods: Size 20/.04 taper and size 25/0.04 of HCM, VB and RC were used. For TRN instruments, size 20/.04 taper (small) and size 26/.04 taper (prime) were used. The instruments were tested in artificial canals with double curvature (coronal curve; 60° curvature, 5 mm radius and apical curve; 70° curvature and 2 mm radius) and single curvature (60° curvature, 5 mm radius). The number of cycles to failure (NCF) was recorded. Data were statistically analyzed by Kruskal-Wallis and Dunn's multiple comparison tests. Weibull analysis was performed on NCF data. Statistical significant was set at p < 0.05.

Results: TRN and HCM revealed higher NCF compared with the other instruments for both tested sizes in single and double curvature canals (p < 0.05). TRN and HCM showed no statistically significant difference in the NCF (p > 0.05). The probability of survival was higher for HCM and TRN instruments than VB and RC instruments.

Conclusions: HCM and TRN instruments were more resistant to cyclic fatigue than VB and RC instruments in single and double curvature canals. HCM and TRN instruments were anticipated to survive with higher number of cycles than the other tested instruments. RC instrument had the lowest fatigue resistance than the other instruments.

Keywords: Cyclic fatigue; Double curvature; Heat-treated alloy; TruNatomy; Weibull analysis.

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Conflict of interest statement

The authors declare that they have no competing interests.

Figures

Fig. 1
Fig. 1
Schematic illustration of cyclic fatigue testing device. The instruments were immersed in saline during testing at 37 ± 1 °C. The handpiece was held by a jig during testing
Fig. 2
Fig. 2
SEM images (× 200) of fractured fragments in double curvature canals. Fracture of instruments in apical curvature (a-d) and coronal curvature (e-h). (a, e) TRN, (b, f) HCM, (c, g) VB and (d, h) RC; respectively. The following features could be observed: the origin of the crack (arrow), fatigue zone (f), and overload fast fracture zone (o)
Fig. 3
Fig. 3
Survival probability plots for TRN, HCM, VB and RC instruments in single and double curvature canals. (a-c) Instruments with size 20/.04 taper for single, double apical and double coronal curvatures; respectively. (d-f) Instruments with size 25/.04 taper for single, double apical and double coronal curvatures; respectively
See this image and copyright information in PMC

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