Cyclic Fatigue Resistance of One Curve, 2Shape, ProFile Vortex, Vortex Blue, and RaCe Nickel-Titanium Rotary Instruments in Single and Double Curvature Canals.

INTRODUCTION

The aim of this study was to evaluate and compare the resistance to cyclic fatigue of the new One Curve (OC) instrument in double (S-shaped) and single curvature canals compared with other nickel-titanium rotary instruments.

METHODS

Size 25/.06 of OC, 2Shape (TS), Vortex Blue (VB), ProFile Vortex (PV), and RaCe (RC) instruments were tested inside artificial canals with a single curvature (60° curvature, 5 mm radius) and double curvature (coronal curve, 60° curvature, 5 mm radius; and apical curve, 70° curvature and 2 mm radius) while immersed in saline at 37°C ± 1°C. The number of cycles to failure (NCF) was calculated, and the fracture surface was examined by using a scanning electron microscope. The data of NCF and fragment length were analyzed by using one-way analysis of variance and Tukey post hoc tests. The t test was performed between the data of fragment length in different curvatures. The level of significance was set at P < .05.

RESULTS

The VB instrument had a significantly higher NCF compared with the other instruments in double (S-shaped) and single curvature canals (P < .05). There was no significant difference between OC and TS in the NCF in single, apical, and coronal double curvature canals (P > .05). The lowest NCF values were recorded for RC instrument in all curvatures (P < .05).

CONCLUSIONS

The fatigue resistance of VB was greater than that of other instruments. OC and TS instruments displayed superior cyclic fatigue resistance than PV and RC instruments.