Antimicrobial activity of root canal irrigants associated with cetrimide against biofilm and planktonic Enterococcus...

To evaluate the antibacterial activity of sodium hypochlorite (NaOCl) and chlorhexidine (CHX) alone or associated with cetrimide (CTR), and QMiX against biofilm and planktonic Enterococcus faecalis (E. faecalis) [American type culture collection (ATCC) 29212].

The solutions 2.5% NaOCl, 2.5% NaOCl + 0.2% CTR, 2% CHX, 2% CHX + 0.2% CTR, 0.2% CTR, and QMiX were evaluated. E. faecalis biofilms were induced for 14 days on bovine dentin blocks. The irrigants were evaluated after contact with E. faecalis suspension and biofilm for 1 and 3 minutes. After that, serial decimal dilutions were made and plated on tryptic soy agar (TSA) medium. Plates were incubated for 24 hours at 37°C and the colony-forming unit (CFU) 1 ml was determined. Data were subjected to ANOVA and Tukey's tests at 5% significance.

All microorganisms were eliminated by direct contact of the irrigants with planktonic cells. Only NaOCl and NaOCl + CTR were able to completely eliminate the microorganisms by direct contact with E. faecalis biofilm. CHX presented effectiveness similar to CHX + CTR CTR, and QMiX after 1 minute of contact and similar to NaOCl and NaOCl + CTR after 3 minutes (p > 0.05), but was unable to completely eliminate the microorganisms. CTR and QMiX did not differ from each other.

CTR addition to CHX and NaOCl solutions did not improve the antimicrobial activity against biofilm. All evaluated irrigants and associations presented activity against planktonic E. faecalis. Only NaOCl and NaOCl + CTR eliminated biofilm after 1 and 3 minutes of direct contact.