Surface roughness and cyclic fatigue resistance of reciprocating and novel rotary instruments after use in curved root canals

This study evaluated surface wear and resistance to fracture of reciprocating and novel rotary instruments after use in curved canals. Twenty new instruments (n = 5/each group): Reciproc Blue, WaveOne Gold, XP-endo Shaper (XPS) and TruNatomy were used twice for the instrumentation of simulated curved canals in plastic blocks. The instrumentation was performed according to the manufacturer's instructions at body temperature. Surface roughness was evaluated, using a profilometer, before instrumentation and twice after the instrumentation. Instruments were, then, subjected to a cyclic fatigue test to evaluate the time to failure. Differences were assessed using ANOVA and post hoc tests (α = 0.05). The XPS instruments showed significantly higher values of roughness compared with TruNatomy at every stage, especially after the second use (p < 0.008). Reciprocating instruments showed superior cyclic fatigue resistance compared with novel rotary instruments (p < 0.05). TruNatomy showed minimal surface roughness, and XPS exhibited significantly higher surface roughness.