The purpose of this study was to examine the effect of partial and total immersion in sodium hypochlorite on nickel-titanium rotary files and to determine whether resistance to fracture was influenced by the immersion time. One hundred K3 and 100 ProFile® rotary files were either partially or totally immersed in 5.25% sodium hypochlorite for zero, one, five, thirty, or sixty minutes. After immersion, files were subjected to cyclic fatigue testing. Time to fracture was recorded and analyzed by a two-way ANOVA. Tukey\u27s honest significant difference was used to identify any differences in immersion times. Within all ProFile groups and partial immersion K3 groups, there was no significant decrease in time to fracture with increased immersion time in sodium hypochlorite. Only the K3 total immersion groups revealed a significant decrease in time to fracture with increased immersion time in sodium hypochlorite
