Antibacterial and anti-biofilm activity of AH plus with chlorhexidine and cetrimide.

Introduction: The use of root canal filling materials with antibacterial activity can be considered beneficial to reduce the remaining microorganisms in the root canal system, where Enterococcus faecalis is often found, and prevent recurrent infection. The aim of this study was to evaluate the antimicrobial activity and capacity for inhibiting E. faecalis biofilm formation of AH Plus, alone and mixed with chlorhexidine (CHX), cetrimide (CTR), and combinations of the two.

Methods: AH Plus alone and mixed with 1% and 2% CHX, 0.1%-0.5% CTR, and combinations of both were tested to assess antimicrobial activity by a modified direct contact test and determine inhibition of E. faecalis biofilm formation at 24 hours. The results were expressed as log10 viable counts. Eradication and inhibition of biofilm formation were understood as no bacterial growth or log10 reduction = 5 with respect to the control (AH Plus alone).

Results: AH Plus + CHX showed a low antimicrobial activity with respect to the control (at 2%, log10 reduction = 1.30). None of the tested concentrations achieved eradication or inhibition of biofilm. AH Plus + CTR showed a direct relationship of concentration-antimicrobial effect, reaching a log10 reduction of 2.92 at 0.5% and inhibition of biofilm formation at 0.2%. With the combination CHX + CTR, lower concentrations were needed for the same effect, and eradication and inhibition of biofilm were achieved.

Conclusions: The addition of CHX, CTR, or some combination of both to AH Plus confers it with bactericidal and anti-biofilm activity against E. faecalis.