The aim of this study was to assess cyclic fatigue resistance in rotary nickel-titanium instruments after simulated clinical use in curved root canals (40-degree, 5-mm radius curve). Thirty-six RaCe rotary NiTi files, size #5, taper 0.04, were divided into 3 groups: Groups A, B and C with one, three and five cycles of use, respectively. Time to failure was recorded with a stopwatch in seconds a...