The effect of sodium hypochlorite on the surface characteristics and fatigue resistance of ProFile nickel-titanium instruments.
OBJECTIVE: Evaluate the effect of 5.25% NaOCl on the surface characteristics and fatigue resistance of ProFile. STUDY DESIGN: Eighty new ProFile instruments were divided into 1 control group (CG) and 3 experimental groups (EG1, EG2, EG3). Instruments of EG1 were immersed in 5.25% NaOCl for 24 hours. Instruments of EG2 and EG3 shaped 10 curved root canals, using, respectively, deionized water and 5.25% NaOCl as irrigants. Surface characteristics were observed by scanning electron microscopy. All instruments were then submitted to fatigue tests. Two-way ANOVA tests were employed to compare the results. RESULTS: Surface characteristics showed no alteration after the immersion tests. The fatigue resistance of instruments in EG2 and EG3 was significantly lower than in CG and EG1. CONCLUSIONS: Immersion of ProFile in 5.25% NaOCl for 24 hours had no influence on surface characteristics and fatigue resistance. Simulated clinical use was a decisive factor in the decrease of fatigue life.