Effect of human, dentin, albumin and lipopolysaccharide on the antibacteerial activity of endodontic activity of endodontic irrigants.

Context: Human dentin powder (HD), bovine serum albumin (BSA) and endotoxin (LPS) may affect the antimicrobial activity of irrigating solutions.

Aim: To evaluate the inhibitory effect of HD powder, BSA, and LPS on the antibacterial activity of 0.5%, 1%, 2.5%, and 5% sodium hypochlorite (NaOCl), 2% chlorhexidine (CHX) gel, BioPure mixture of tetracycline, citric acid, and detergent (MTAD), and QMix.

Methods: The direct contact test against Enterococcus faecalis (ATCC 29212) for 2-min, 30-min and 6-h was used. Sterile pyrogen-free water was the negative control. After experimental periods, a neutralizing agent was used. Colony-forming units were determined by 10-fold serial dilutions and culture on agar plates. Data were analyzed by Kruskal-Wallis and Dunn's test (α = 5%).

Results: In the absence of inhibitors, all irrigants eliminated E. faecalis . In contact with HD, all solutions eliminated E. faecalis within 2-min, with the exception of MTAD. In the presence of BSA, only 5% NaOCl killed E. faecalis within 2-min. LPS did not affect the antibacterial effect of any irrigant. At 30-min and at 6-h, all substances eliminated E. faecalis .

Conclusions: In the presence of albumin, irrigants needed >2-min to eliminate E. faecalis , except for 5% NaOCl. The same was observed in the presence of dentin when E. faecalis was exposed to MTAD.