The comparative effectiveness and safety of three activated irrigation techniques in the isthmus area using a transparent tooth model

Aim To compare the effectiveness and safety of three activated irrigation techniques when removing pulp tissue from the isthmus of a transparent tooth model. The three techniques assessed were: the EndoVac (EV), passive ultrasonic irrigation (PUI) and ultrasonic wave aspiration (TUWA). Conventional syringe irrigation (CSI) was used as a control. Methodology A transparent tooth model was created using the mesial root of an extracted mandibular first molar that had an isthmus and two independent mesial canals. An artificial 0.3-mL cylindrical chamber was created below the apical foramen. The tooth was then cleared. After preparation, the root canals were filled with fuchsine-stained bovine pulp tissue. The irrigation protocols were compared in respect of their effectiveness at removing pulp tissue from the isthmus and their safety with regard to irrigantextrusion. For all four groups, 5.25% sodium hypochlorite solution was used as the irrigant. Photographs were taken and analysed using an imaging software. A Kruskal–Wallis test was used to detect the differences between groups (statistical significance was set at P < 0.05). Results No group was associated with extrusion of irrigant beyond the apex. Significant differences were observed between the groups: TUWA was the most effective technique at removing pulp tissue from the isthmus (3.39 mm2; standard deviation (SD) = 0.67; range = 1.25–3.69), followed by PUI (2.16 mm2; SD = 0.38; range = 1.37–2.96), EV (0.73 mm2; SD = 0.14; range = 0.49–0.98) and CSI (0.27 mm2; SD = 0.01; range = 0.26–0.28). Conclusion Ultrasonic wave aspiration was the most effective technique at removing artificial pulp tissue from the isthmus of a transparent tooth model. None of the techniques extruded irrigant. Keywords: efficacy, negative pressure irrigation, safety, sodium hypochlorite, ultrasonic irrigation, ultrasonic needle.