In vitro alteration by dentine and protein of the antimicrobial activity of two endodontic irrigants: Hybenx® and sodium hypochlorite

Irrigant solutions commonly used for the treatment of endodontic infections can be inhibited by both organic and inorganic substances. The aim of this study was to evaluate the in vitro antimicrobial activity of the novel irrigant HybenX® and 2.5% and 5% sodium hypochlorite against Enterococcus faecalis, in presence of dentine powder (DP) or bovine serum albumin 20% (BSA) as inhibitory agents. An E. faecalis American Type Culture Collection (ATCC) 29212 suspension was added to the irrigants (Hybenx® or NaOCl) and one or two different inhibitors (BSA and DP) either after one-hour pre-incubation at 35 ± 1◦ C or not. The antimicrobial activity of HybenX® against E. faecalis was already proved at 15 min and was neither affected by BSA nor by DP or combinations thereof. NaOCl 2.5% showed an effective antimicrobial activity starting from 15 min and this activity was partially inhibited by BSA and BSA plus DP combination within one hour when pre-incubation occurred. NaOCl 5% showed antimicrobial activity within 15 min, which was inhibited within one hour only in the presence of both BSA and DP regardless of the pre-incubation period. HybenX® could represent a good alternative to common irrigants for the treatment of E. faecalis endodontic infections, showing a rapid antimicrobial activity not inhibited by organic and inorganic inhibitors.