RESUMO
This study evaluated the influence of ultrasonic activation (US) on the antimicrobial activity of a new final irrigant containing glycolic acid (GA). Extracted teeth were used, being 70 to counting of colony-forming units (CFUs) and 35 to confocal laser scanning microscopy. Samples were inoculated with Enterococcus faecalis and divided into 7 groups: distilled water + US; 17% EDTA; Qmix; 17% GA; 17% EDTA + US; QMix + US; and 17% GA + US and kept in contact with test solution for 1 min in the groups with or no US. In the CFUs, the highest bacterial reduction was observed in QMix + US group, followed by QMix and GA + US. In the confocal evaluation, the lowest number of viable cells was observed in EDTA + US, with no statistical difference from QMix, QMix + US and GA + US (P > 0.05). The use of US improves the antimicrobial activity of EDTA and GA, being statistically different from the isolated use of these final irrigants in both evaluation tests.