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

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  • Satnam S. Virdee
  • Firas S. Albaaj
  • Damien Walmsley
  • Josette Camilleri
  • Paul R. Cooper
  • Phillip L. Tomson


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
tests (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:
Within 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.

Enterococcus Faecalis
Sodium Hypochlorite