Efficacy of different final irrigation activation techniques on smear layer removal

Different techniques and irrigant delivery devices have been proposed to increase the flow and distribution of irrigating solutions within the root canal system. The aim of this study was to compare smear layer removal after final irrigant activation with apical negative pressure (ANP), manual dynamic agitation (MDA), and passive ultrasonic irrigation (PUI).

Forty single-rooted human mandibular premolars were decoronated to a standardized length of 16 mm. They were cleaned and shaped by using ProTaper system to size F4 and NaOCl 2.5%. The specimens were divided into 4 equal groups (n = 10) according to the final irrigation activation technique: group 1, passive irrigation (PI); group 2, apical negative pressure (ANP) (EndoVac); group 3, manual dynamic activation (MDA); and group 4, passive ultrasonic irrigation (PUI). Samples were split longitudinally and examined under scanning electron microscope for smear layer presence.

PI and PUI had the highest smear scores, with no significant differences between them. This was followed by MDA and finally ANP, which showed the statistically significant lowest mean score at P ≤ .05.

Final irrigant activation with ANP and MDA resulted in better removal of the smear layer than with PUI or PI.