Antibacterial efficacy of conventional and single-use Ni-Ti endodontic instruments: an in vitro microbiological evaluation

Purpose: The purpose of this in vitro study was to investigate the capability of different Ni-Ti instru- ments in disinfecting root canals previously infected with E. faecalis. Methods: 60 single-rooted, freshly extracted teeth were selected, sterilized and inoculated with cells of E. faecalis strain. All root canals were shaped with different Ni-Ti instruments (MTwo, Revo-S, Reciproc, and OneShape) under irrigation with NaOCl and 17% EDTA solutions by the same trained operator. The number of Colony Forming Units (CFU)/ml of E. faecalis was evaluated for each group. Numeric data were submitted to statistical analysis. Results: MTwo, REVO-S, Reciproc and OneShape reported significantly lower CFU/ml values and showed no significant differences among them (p>0.05). All groups showed significantly higher CFU/ ml values than not treated samples (negative control). Conclusions: All the Ni-Ti instrumentation efficiently reduced E. faecalis counts and no significant differences were found among them. Single-use files can offer antibacterial results comparable with traditional instruments.