Effect of ultrasonic versus laser-activated irrigation on smear layer removal - An in vitro analysis

Elimination of the smear layer from root canal walls remains a clinical challenge, as residual debris can compromise sealer adaptation and endodontic treatment outcomes. Therefore, it is of interest to compare the efficacy of passive ultrasonic irrigation and erbium-doped yttrium aluminum garnet (Er:YAG) laser-activated irrigation in removing smear layer at different canal levels. Sixty extracted single-rooted human premolars were allocated to four groups: conventional syringe irrigation, passive ultrasonic irrigation and Er:YAG laser-activated irrigation at 1.0 W and 1.5 W using sodium hypochlorite and EDTA. Scanning electron microscopy evaluation demonstrated that both activation techniques significantly improved smear layer removal compared with conventional irrigation at all canal levels (p<0.001). Thus, Er:YAG laser-activated irrigation at 1.5 W showed superior smear layer removal in the apical third, suggesting its potential as an effective adjunct in contemporary endodontic practice.