Antimicrobial Efficacy of Different Irrigant Solutions Using a Novel Biofilm Model: An In Vitro Confocal Laser Scanning Microscopy Experiment

Aim: To determine the ability of different irrigation solutions to biomechanically remove Enterococcus faecalis biofilm from a novel artificial root canal model during chemomechanical preparation. Methods: High resolution micro-computer-tomography scans of a mandibular molar’s mesial root were used to produce 50 identical 3D-printed resin root canal models. These were cultured with E.faecalis over seven days to generate biofilm and subjected to chemomechanical preparation using: saline; 17% ethylenediaminetetraacetic acid (EDTA) or 2% sodium hypochlorite (NaOCl) alongside positive/negative controls (n = 10). Canals were prepared to 40/.06 taper, with 1 mL irrigation between instruments, followed by 5 mL penultimate rinse, 30 s ultrasonic activation and 5 mL final rinse. Residual biofilm volume (pixels) was determined following immunofluorescent staining and confocal-laser-scanning-microscopy imaging. Statistical comparisons were made using Kruskal-Wallis with post-hoc Dunn’s ntests (α <0.05). Results: In all canal thirds, the greatest biofilm removal was observed with NaOCl, followed by EDTA and saline. The latter had significantly higher E.faecalis counts than NaOCl and EDTA (P <0.01). However, no statistical differences were found between EDTA and NaOCl or saline and positive controls (P >0.05). Conclusions:nWithin limitations of this model, 17% EDTA was found to be as effective as 2% NaOCl at eradicating E.faecalis biofilm following chemomechanical preparation. Further investigations with multi-species biofilms are encouraged.

Biofilm Enterococcus Faecalis EDTA Sodium Hypochlorite CLSM Irrigants