Introduction
Sodium hypochlorite (NaOCI) is widely used as an irrigation solution in endodontics due to its favorable physicochemical and antibacterial properties [Passive ultrasonic irrigation (PUI involves avtivating irrigation solutions used ultrasonic tips operating at frequencies of 25–40 kHz. This method increases the effective surface area of the solutions through ultrasonic vibrations generated in the root canal, leading to more efficient cleaning [Therefore, the aim of this study is to histologically evaluate the efficiency of pulp residue and debris removal using both 2.5% and 5.25% NaOCI solutions, in combination with activation through laser, ultrasonic, and intracanal heating methods during the final irrigation step.