Effects of irrigation on debris and smear layer on canal walls prepared by two rotary techniques: a scanning electron microscopic study.

Debris and smear layer were evaluated in canals prepared with either Lightspeed (LS) or ProFile (PF) rotary instruments. Irrigants used were tap water (group A) or alternating 5.25% NaOCl and 17% EDTA (group B). Apical stops were prepared to size 52.5 in the LS and to size 6 (approximately ISO size 36) in the PF techniques. The roots were split longitudinally and examined at apical, middle and coronal levels for debris and the smear layer using a 5-step scale. Using only water, mean debris scores were similar for LS and PF. In contrast, with EDTA/NaOCl, LS- and PF-prepared canals had similar debris scores at the apical and coronal levels, but there was a significant difference at the middle level. Mean smear layer scores were similar in LS- and PF-shaped canals when water was the sole irrigant. In contrast, with NaOCl and EDTA, mean smear layer scores were significantly different at the apical and middle levels, but not at the coronal level. Neither technique was superior in removing debris, but larger canal preparations obtained in this study with LS instruments enabled a more effective removal of the smear layer in the EDTA-NaOCl group.