Aim: The aim of this study the effect of heat treatment on flexibility, cyclic fatigue and of OneCurve nickel-titanium (Ni-Ti) rotary file (OC) and compare them with those of EdgeFile (EF) NiTi file as both files manufactured from a controlled memory wire.
Methods: A sample of 45 instruments with tip size of 25 and 0.06 taper from both OC and EF were selected for the current study. The cyclic fatigue testing was performed using dynamic mode. The bending resistance was tested using the universal testing machine and files were bent until reach 45°. In addition, dispersive scanning calorimetric analysis (DSC) was carried out for identification of Af transformation temperature. An independent t-test was used in the statistical analysis and significance difference was set at p-value 0.05.
Results: The EF files showed significantly greater resistance to cyclic fatigue (p<0.05). As well as, the EF exhibited less bending resistance than OC (p<0.5). The DSC analysis showed that the OC has an Af near 54°C, while the EF was near 57°C.
Conclusions: The EdgeFile NiTi rotary instruments have high flexibility and high resistant to cyclic fatigue than OneCurve does when tested in dynamic mode and both have a close has an Af temperature exceeding 50˚C