Hydrogen-rich electrolyzed water is a useful mouthwash due to its biofilm-control properties: an in vitro and in vivo study.

Background: Previous studies have demonstrated the inhibitory effect of hydrogen-rich water on biofilm formation. However, hydrogen-rich electrolyzed water (HEW) has not been evaluated as mouthwash, despite being economical, convenient, and biologically safe. We assessed the antibiofilm effects of HEW on Streptococcus mutans and its potential as a mouthwash.

Methods: The effect of HEW on S. mutans growth was assessed by measuring bacterial colony-forming units, and biofilm formation capacity was examined by crystal violet staining after culturing on a polystyrene plate. The effect of HEW on biofilm formation-related gene expression in S. mutans was assessed by real-time polymerase chain reaction. Finally, the effect of HEW on salivary S. mutans and plaque maturation was evaluated in 24 participants; after gargling with HEW twice daily, the salivary S. mutans count was quantified using a Caries Risk Test bacteria kit (Ivoclar Vivadent AG), and plaque maturation was compared using quantitative light-induced fluorescence imaging.

Results: Exposure to HEW resulted in no significant changes in S. mutans growth but a significant reduction in biofilm formation in vitro (p<0.001). Furthermore, the gene expression of glucosyltransferases (gtfB, gtfC) was significantly lower than that in the control group treated with tap water (p<0.05, p<0.01). S. mutans counts and plaque maturation were significantly lower in participants who gargled with HEW than in those who gargled with tap water (p<0.01).

Conclusion: Our data suggest that oral rinsing with HEW exerts antibiofilm effects on S. mutans, indicating that it can be used as a mouthwash to treat dental biofilm-dependent diseases.