Effect of sodium hypochlorite and saline on cyclic fatigue resistance of WaveOne Gold and Reciproc reciprocating instruments

AimTo compare the cyclic fatigue resistance of WaveOne Gold (Dentsply Tulsa Dental Specialties, Tulsa, OK, USA) and Reciproc (VDW, Munich, Germany) reciprocating instruments during immersion in sodium hypochlorite (NaOCl) and saline solutions at body temperature. MethodologyA total of 180 new WaveOne Gold primary size 25, .07 taper, and Reciproc size 25, .08 taper were randomly divided into three groups: group 1: no immersion (control, air); group 2: immersion in saline at 371 degrees C; and group 3: immersion in 5% NaOCl at 371 degrees C. The instruments were reciprocated in the test solution until fracture, and the number of cycles to failure was recorded. The data were analysed statistically using t-tests and one-way analysis of variance (anova) with the significance level set at P<0.05. A Weibull analysis was performed on number of cycles to failure data. ResultsWaveOne Gold instruments had significantly greater number of cycles to failure than Reciproc instruments in all groups (P<0.001). Fatigue resistance for both instruments tested in air was significantly higher than that in saline and NaOCl solutions (P<0.001). For both instruments, there was no significant difference in the fatigue resistance between saline and NaOCl solutions (P>0.05). The Weibull analysis showed that the predicted cycles of WaveOne Gold in air was 1027 cycles for 99% survival. However, Reciproc instruments tested in NaOCl solution had the lowest predicted cycles (613 cycles) among the groups. ConclusionsImmersion of WaveOne Gold and Reciproc reciprocating instruments in saline and NaOCl solutions decreased considerably their cyclic fatigue resistance. The fatigue resistance of WaveOne Gold instruments was higher than that of Reciproc instruments.