Subgroup B: passive ultrasonic irrigation
NaOCI was activated using ultrasonic device (VDW, Munich, Germany). The device was set to a power setting of 30, and activation was performed using a 21 mm-IRR20 irrigation tip placed 1 mm behind the working length. The tip was positioned away from the dentinal walls and activated for 20 s. This activation procedure was repeated 3 times, using fresh NaOCl solution for each cycle.