In vitro efficacy of different irrigating solutions against polymicrobial human root canal bacterial biofilms.

The purpose of this in vitro study was to compare the antimicrobial efficacy of five different irrigating solutions against complex polymicrobial bacterial biofilms harvested from root canals to model actual endodontic irrigation as closely as possible, and to test the efficacy of these irrigants in these conditions. Two multi-species in vitro biofilms were generated from bacterial samples taken from patients presenting with acute pulpitis. The microbial composition of these samples was characteristic of the disease. The biofilms were incubated with 1000 p.p.m. Solumium Dental (ClO(2)), 0.2% chlorhexidine (CHX), 5.25% sodium-hypochlorite (NaOCl), 5.25% Neomagnol, 10% iodine and phosphate buffered saline (PBS) as control. After the microbiological preparation of the samples, colony forming units (CFU) were counted. NaOCl, iodine and Neomagnol were the most effective, whilst CHXand Solumium appeared to be less effective against these specific biofilms. The efficacy of the most effective agents differed according to biofilm and application time. All irrigants were efficient to some extent, but NaOCl proved to be the most efficient, while chlorine dioxide (ClO(2)) yielded the poorest results in these circumstances. The efficacy of NaOCl was already well-known, but our results also point out that iodine could have an important role in endodontic irrigation.