Biofilm disruption by root canal irrigants and potential irrigants

Abstract

Aim To investigate the disruption and bactericidal effect of root canal irrigants on single and dual‐species biofilms.Methodology Single‐species (Streptococcus sanguis, Enterococcus faecalis, Fusobacterium nucleatum, Porphymonas gingivalis) and dual‐species (S. sanguis and F. nucleatum) biofilms were grown on nitro‐cellulose membranes and immersed in either a commonly used root canal irrigant; (NaOCl, EDTA, Corsodyl®, iodine) or potential root canal irrigant [sodium dodecyl sulphate (SDS), cetyl trimethyl ammonium bromide (CTAB) and Tween®80] for 1, 5 or 10 min. The number of viable and nonviable bacteria disrupted from the biofilm and those remaining attached to the biofilm were determined using a viability stain in conjunction with fluorescent microscopy. In addition, confocal laser scanning microscopy (CLSM) was used to allow a visual assessment of the disruptive effects of selected agents on the stained biofilms.Results Gram‐negative species were more susceptible to cell removal than their Gram‐positive counterparts, S. sanguis being the least susceptible. The majority of the cell disruption occurred after the first minute of exposure as all of the agents exerted some effect on bacterial disruption and viability; however, the extent varied according to the agent. The most effective root canal irrigant for disrupting biofilms was NaOCl whilst in contrast iodine was generally effective at bacterial killing but not disruption. Of the potential root canal irrigants, CTAB and SDS were both effective in disrupting the biofilm and at bacterial cell‐killing.Conclusions Biofilm disruption and cell viability were influenced by the species, their co‐association in dual‐species biofilms and the test agent. The effectiveness of NaOCl as an endodontic irrigant was reinforced.