Antimicrobial and biocompatible potential of peracetic acid as a novel root canal irrigant

Background Sodium hypochlorite (NaClO) is currently the most widely used irrigant in root canal treatment; however, it exerts cytotoxic effects on the periapical tissues. To reduce the biological risk, we aimed to investigate the potential usefulness of a peracetic acid (PAA)-based disinfectant as an alternative to root canal irrigants. Methods The antibacterial activity of the PAA-based disinfectant, Actril (MEDIVATORS, Minneapolis, MN, USA)—against oral pathogenic bacteria—was evaluated by determining its minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and minimum biofilm inhibitory concentration (MBIC). Cytotoxicity toward periodontal tissue-related cells was assessed using a Cell Counting Kit-8 assay. The bactericidal effect against Enterococcus faecalis biofilms was further examined using live/dead staining. To simulate the clinical environment, E. faecalis biofilms were established on extracted human teeth, and the irrigation efficacy of Actril in root canals was evaluated using scanning electron microscopy (SEM) and quantitative polymerase chain reaction (qPCR). Data were analyzed using one-way analysis of variance followed by Tukey’s test or the Kruskal–Wallis test with Steel–Dwass post-hoc comparisons, as appropriate. Results Actril demonstrated strong antibacterial activity against oral pathogenic bacteria at a PAA concentration of 9.4×10⁻⁴%, which was significantly lower than the effective concentration of NaClO, while showing reduced cytotoxicity against periodontal tissue-related cells. Live/dead staining revealed that Actril exerted bactericidal effects against E. faecalis within the biofilms. Furthermore, SEM observations demonstrated the removal of biofilm structures from the root canal surface, and qPCR analysis confirmed a significant reduction in the number of viable E. faecalis cells. These findings indicate that Actril is not only effective against pathogenic microorganisms but also exhibits superior biocompatibility compared with NaClO solution. Conclusions The PAA-based disinfectant shows promise as a safe and effective alternative root canal irrigant to conventional NaClO solutions.