The effects of Easydo Activator (EA), a new sonic irrigation system, on sealer penetration at the root apex were compared to needle irrigation (NI) and passive ultrasonic irrigation (PUI) in this study. Forty-two single-rooted teeth were prepared and randomly divided into three groups (n = 14): group 1: NI; group 2: PUI; and group 3: EA. A solution of 3% sodium hypochlorite (NaOCl) was used for irrigation. Nine teeth in each group were filled with AH Plus sealer mixed with CY5 fluorescent dye and a single gutta-percha cone. The sealer penetration area, maximum penetration depth and percentage of sealer penetration at 5 mm and 1 mm from the apex were analyzed by confocal laser scanning microscopy (CLSM). The remaining 5 teeth in each group were subjected to test smear layer scores by scanning electron microscopy (SEM). The CLSM evaluation showed that increases in the area, depth and percentage of sealer penetration were detected at 1 and 5 mm from the root apex in the PUI group compared with the NI group, and greater increases were observed in the EA group (P < 0.05). The SEM experiment showed that the lowest scores for the smear layer and debris removal were achieved by the EA group when compared with the PUI and NI groups (P < 0.05). In conclusion, EA was superior to PUI and NI regarding sealer penetration at the root apex during endodontic treatment, and it could provide a new technical idea for clinical root canal therapy.

BACKGROUND: The aim of this study was to investigate the effects of endodontic sealer types and ultrasound on smear layer removal after post space preparation.
METHODS: Thirty-six bovine incisors were chemomechanically instrumented and randomly divided into 3 groups (n = 12) according to the endodontic sealer (AH Plus [Dentsply DeTrey, Konstanz, Germany], Apexit Plus [Ivoclar Vivadent AG, Schaan, Fürstentum Liechtenstein], or iRoot SP [Innovative Bioceramix, Vancouver, BC, Canada]) used during root canal obturation, and the groups were further subdivided randomly into 3 subgroups (n = 4) based on the post dowel irrigation systems (ultrasound, regular rinse, or control) used. The samples were examined under a scanning electron microscope and were scored for debris and tubule openings using a 3-scale grading system. The Friedman test, Wilcoxon signed rank test, Kruskal-Wallis analysis, and Mann-Whitney U test were used to statistically analyze the results (α = 0.05).
RESULTS: Samples in the AH Plus group were more easily debrided than those in the iRoot SP group (P < .05). The best tubule opening condition was presented in samples in the AH Plus group, whereas those in the iRoot SP group presented the worst (P < .05). The regular rinse and ultrasonic groups were similarly good at smear layer removal and tubule opening (P > .05) compared with the control group (P < .05). The samples using AH Plus in combination with ultrasound or syringe rinsing showed the best cleaning result among all of the subgroups (P < .05).
CONCLUSIONS: AH Plus presented the easiest removal from the post space, whereas iRoot SP presented the most difficult removal. Ultrasound improved the cleaning efficacy of post dowels as did the regular rinse.