The length of each canal was visually established by placing a #15 file (Dentsply-Maillefer, Ballaigues, Switzerland) into each tooth until the tip of the file was visible at the apex. The stopper was placed at cementoenamel junction which was the reference point. The working length was determined by subtracting 1 mm from the previous length. The canals were prepared up to #45 K-file using the step-back technique and the shaping of middle and coronal thirds was carried out by #3 and #4 Gates-Glidden drills (Dentsply-Maillefer, Switzerland).