Antimicrobial effects of various endodontic irrigants on selected microorganisms

Aim This study was undertaken to determine the antimicrobial effect of vari ous endodontic irrigants against six selected microorganisms. Methodology Staphylococcus aureus, Enterococcus faecalis, Streptococcus sal ivarius, Str. pyogenes, Escherichia coli and Candida albicans were included in the study. Pre-sterilized Whatman paper discs, 6 mm in diameter and soa ked with the test solution, were prepared and placed onto the previously se eded agar Petri plates. Each plate was incubated aerobically. A zone of inh ibition was recorded for each plate and the results were analysed statistic ally. Results 5.25% NaOCl was effective against all test microorganisms with a su bstantial zone of inhibition. Saline was always ineffective. Decreased conc entration of NaOCl significantly reduced its antimicrobial effect. Cresophe ne showed a significantly larger (P < 0.05) average zone of inhibition comp ared to the other experimental irrigants. Alcohol had smaller but not signi ficantly different zones of inhibition than chlorhexidine. Conclusions 5.25% NaOCl was superior in its antimicrobial abilities compare d with other irrigants used. A reduced concentration of NaOCl (0.5%) result ed in significantly decreased antimicrobial effects. When compared with 21% alcohol, 0.5% NaOCl and 2% chlorhexidine, paramonochlorophenol (cresophene ) showed a greater antimicrobial effect.