Rania Lebbos | Naji Kharouf | Jamal Jabr | Cynthia Kamel | Roula El Hachem | Youssef Haikel | Marc Krikor Kaloustian

The aim of this study was to determine the effect of apical preparation size and preparation taper on smear removal using a metallic needle and a new polymer needle (IrriFlex, Produits Dentaires SA « PD », Vevey, Switzerland).

For all groups, there was significantly higher smear layer in the apical third (p < 0.001) compared with the coronal and middle thirds. The 25, 0.06 preparation demonstrated better cleaning efficiency than the 30, 0.04 preparation throughout the canal when irrigated with a metallic needle; however, there were no significant differences in the middle and apical thirds when IrriFlex was used. There were also no differences of smear layer removal between G1 and G3 and G2 and G4 in the coronal part. In the middle and apical parts, G1 showed better elimination of smear layer compared with G3. There were slight differences in the middle third between G2 and G4, while G2 showed less cleaning efficiency compared with G4 in the apical third (p ¼ 0.022)