Differential Antimicrobial Effects of Endodontic Irrigant Endocyn on Oral Bacteria

Endocyn is a root canal irrigant with a stable formulation of hypochlorous acid (HOCl), and should have significant antimicrobial effects. However, there are no available studies that evaluate these effects on different types of bacterial species. In this prospective in vitro study, bacterial species were grown with and without the addition of Endocyn to measure the effects on the Gram-positive bacteria Actinomyces naeslundii, Lactobacillus acidophilus, Streptococcus gordonii, and Streptococcus mutans, as well as the Gram-negative bacteria Porphyromonas gingivalis, Fusobacterium nucleatum, and Veillonella parvula. Turbidity was measured at 24 h, and the differences between the baseline and experimental treatments were measured using two-tailed Student’s t-tests and verified using ANOVA. Gram-positive bacteria were inhibited in the range of −8.2% to −35.5%, p = 0.14 to p = 0.004, while Gram-negative bacteria were inhibited in the range of −16.7% to −41.4%, p = 0.04 to p = 0.001, which were similar to the effects of 5% NaOCl (bleach). These data demonstrated that Gram-positive bacteria were somewhat resistant to Endocyn at lower levels but were inhibited at all higher concentrations, while Gram-negative bacteria were susceptible to Endocyn at all levels, and increased at higher concentrations. These results provide clinically relevant data regarding the efficacy of this disinfectant against common oral pathogens (and commensal bacteria), and are important as they provide evidence regarding public health and the environmental safety of clinical protocols regarding endodontic hygiene.