Effectiveness of Passive Ultrasonic Irrigation Protocols in Simulated Complex Root Canal Cavities

This study aimed to evaluate the effectiveness of different Passive Ultrasonic Irrigation (PUI) protocols on debris removal and exposure of dentinal tubules in simulated complex root canal cavities. Twenty single-rooted human mandibular premolars with simulated root canal cavities were filled with the debris and randomly divided into ten groups based on the final irrigation protocol: 1—positive control; 2—negative control; 3—conventional irrigation (CI) with 2.5% sodium hypochlorite (NaOCl); 4—CI with 17% ethylenediaminetetraacetic acid (EDTA) followed by NaOCl; 5—three cycles of PUI for 20 s (NaOCl-NaOCl-NaOCl); 6—three cycles of PUI for 20 s (NaOCl-EDTA-NaOCl); 7—one 60 s PUI cycle (NaOCl); 8—one PUI 180 s cycle (NaOCl); 9—two cycles of PUI for 60 s (EDTA-NaOCl); and 10—two cycles of PUI for 60 s (NaOCl-EDTA). The groups were analyzed by SEM. The Kruskal-Wallis test was used at a 5% level. PUI showed a higher reduction of debris, similar to the positive control group (p > 0.05) and higher than the CI and negative control groups (p < 0.05). Regarding the exposure tubules, the CI groups were similar to the negative control group in all cavities (p > 0.05). The PUI groups were similar to the positive control group (p > 0.05). However, only groups 6, 7, and 10 were statistically different from the CI and negative control (p < 0.05). The protocols using PUI, comprising groups with three cycles of 20 s (NaOCl-EDTA-NaOCl), two cycles of 60 s (EDTA-NaOCl), or one cycle of 60 s (NaOCl), were more effective at removing debris and increasing the exposure of dentinal tubules.