RESUMO
BACKGROUND AND OBJECTIVES: Evolution in understanding the poly-microbial environment of both endodontic infections and that of failed root canal treatments has been debatable over the years. The present study was designed to compare and analyze the effect of various root canal irrigation solutions on certain endodontic pathogens in vitro. MATERIALS AND METHODS: To analyze in vitro the zone of inhibition of the micro-organisms the following irrigating solutions were employed: a. Sodium hypochlorite (NaOCl) 5% b. Sodium hypochlorite (NaOCl) 3% c. Chlorhexidine 2% d. Chlorhexidine (CHX) 0.12% e. Doxycycline 0.01% f. Doxycycline 0.005% g. MTAD. An agar culture plate inoculated with four endodontic pathogens was used namely 1. Enterococcus faecalis (MTCC-439) 2. Candida albicans (MTCC-183) 3. Fusobacterium nucleatum (ATCC-25586) 4. Peptostreptococcus anaerobius (ATCC-27337) The inoculums were streaked out on the trypticase soy agar plate for discrete colonies with a wire loop using standard method. The inoculated plates carrying the antibiotic disks were incubated in an anaerobic jar in the following way-Anaerobic incubation-the following procedure was used to provide anaerobiosis with an increased concentration of carbon dioxide. By this method the zone of inhibition obtained by different irrigating solutions against different pathogens could be compared. RESULTS: MTAD showed maximum antibacterial activity. In case of C. albicans MTAD was less effective than 5% NaOCl, 3% NaOCl and 2% CHX, 0.12% CHX. However, it was more effective against E. faecalis, F. nuleatum and P. anaerobicus. In any case, antimicrobial activity is not the only prerequisite for an endodontic irrigant. E. faecalis strain used in this study showed resistance to doxycycline; also doxycycline was ineffective against C. albicans at 0.01% and 0.005% concentrations. CONCLUSION: It was found that MTAD was more antimicrobial than 5% NaOCl for some of the test micro-organisms; however the ability of MTAD to dissolve pulp tissue is not comparable to 5% NaOCl. In addition, 5 and 3% NaOCl showed signifcant antimicrobial activity against all test micro-organisms. The best option for a primary endodontic irrigant therefore is 5% NaOCl.
