Aim: The study aimed to compare 10% Glycolic acid as a single irrigant versus 2.5% sodium hypochlorite followed by 17% Ethylenediaminetetraacetic acid (EDTA) in terms of E. faecalis count reduction and smear layer removal in single-rooted teeth.

Methodology: Thirty human extracted mandibular premolars were prepared and inoculated with E. faecalis for one week to evaluate E. faecalis count reduction. Teeth were randomly assigned to two groups (n = 15) according to the irrigation protocol used. Group I: intervention (10% Glycolic acid) and Group II: Control group (Irrigation using 2.5% NaOCl followed by 17% EDTA). After 24 hours of incubation, bacterial count reduction using colony forming units CFUs/ml was determined. For evaluating the ability of irrigants to remove the smear layer, another twenty-two mandibular premolars were chosen and randomized into two groups (n = 11). During “chemo-mechanical” preparations, the root canals were irrigated with different irrigation protocols according to each group. Then, the roots were split longitudinally in the bucco-lingual direction into two halves. A smear layer assessment was conducted on the “coronal, middle, and apical thirds” of the root canal using an Environmental Scanning-Electron Microscope (ESEM) at 1000x magnification.

Results: Regarding E. faecalis count reduction, there was “no significant” difference between the two groups (p = 0.14). Regarding the ability to remove the “smear layer”, there was no significant difference between the two groups at coronal, middle and apical. While comparing smear layer scores within the same group, the “apical third” showed a significantly higher smear layer score in the two groups.

Conclusion: Glycolic acid can be used as a single irrigant owing to its antibacterial efficacy and the ability to remove the smear layer.