In vitro evaluation of antimicrobial efficacy of endodontic irrigants

Purpose: The objective of this study was to compare in vitro, by MTT assay, the antimicrobial efficacy of Niclor 5 (5% NaOCl solution), Cloreximid (0.2% chlorhexidine and 0.2% cetrimide solution), 3% hydrogen peroxide and 17% EDTA against two microorganisms associated with primary endodontic infections. Methods: Enterococcus faecalis and Streptococcus mutans strains were selected for this test. Freshly extracted single-rooted human teeth were endodontically treated, inoculated with bacterial strains and then divided into different groups, each of them rinsed with Niclor 5 (5% NaOCl solution), Cloreximid (0.2% chlorhexidine and 0.2% cetrimide solution), 3% hydrogen peroxide,17% EDTA and with 5% NaOCl solution (positive control). Results: Even though all the tested irrigating solutions demonstrated antibacterial effects against E. faecalis and S. mutans, the results were significantly different between the various groups. The greatest antimicrobial effects were observed in groups treated with 5% NaOCl and 17% EDTA. Interestingly, the effectiveness of EDTA could be ascribed to its capability of detaching biofilm from canal walls.