introduction: the aim of this study was to verify the effect of alternating 2.5% sodium hypochlorite (naocl) and 17% ethylenediaminetetraacetic acid (edta) on the smear layer removal from root canal surfaces. methods and materials: a total of 15 single-rooted human teeth, instrumented with protaper files, were randomly distributed in 3 groups. in group 1 ( n =7) the canals were irrigated with 1...