Effectiveness of Acid-electrolyzed Functional Water for Mouth Wash: An In Vitro Study

Abstract

Background/aim: Acid-electrolyzed functional water (FW) is an efficient bactericide and gargling with FW might be an effective method of oral care. We investigated the possible use of FW as a mouth wash by an in vitro study.

Materials and methods: The bactericidal effect of FW against different species of bacteria (Staphylococcus aureus, Streptococcus pneumonia, Pseudomonas aeruginosa, and Candida albicans) was evaluated using the numbers of colony-forming units (CFU). The experiment was conducted using PBS, LISTERINE, and ConCool F (undiluted, and the optimal concentration indicated). To investigate the bactericidal mechanism of FW, the activity of superoxide dismutase (SOD), an indicator of oxidative action, was measured in S. aureus. FW was diluted with purified water to concentrations of 10, 30, 50, and 70%. The numbers of CFU were measured for each concentration. XTT assays were performed using HSC-3 and HeLa cells, to examine the viability of the cells following treatment with FW. The same experiment was conducted with PBS, LISTERINE, and undiluted ConCool F.

Results: No bacteria treated with FW formed colonies. SOD activity peaked at a 50% concentration of FW and was more than twice that of the control. A significant decrease in the number of CFU was observed following 50% treatment. Since the peaks of the SOD activity and the starting concentrations of the bactericidal effects coincided, the bactericidal effect of FW might be related to its oxidative effects. Bacteria treated with FW had the same survival rate as the other mouth washes.

Conclusion: FW might be clinically applicable as a mouth wash.

Keywords: Acid-electrolyzed functional water; aspiration pneumonia; elderly; mouth wash; oral care.

Figure 1. Bactericidal effects of each solution. The colony number was counted 24 h after plating, and the number of colony-forming units (CFUs) was also counted. (A) S. aureus, (B) S. pneumoniae, (C) P. aeruginosa, and (D) C. albicans. The data are expressed as mean±SD. *p<0.001 vs. PBS.

Figure 2. Effect of superoxide dismutase activity after treatment. (A) Comparison of superoxide dismutase activity of S. aureus after treatment with various concentrations of functional water. (B) The colony numbers were counted 24 h after treatment, and the colony-forming units were also calculated. The data are expressed as mean±SD from at least four independent experiments. *p<0.05 vs. PBS. **p<0.001 vs. PBS.

Figure 3. Viability of cells after treatment. (A) HeLa, low density (1×10⁴/well), (B) HeLa, high density (1×10⁵/well). We show the OD score and cell viability (line). (C) HSC-3, low density (1×10⁴/well), (D) HSC-3, high density (1×10⁵/well). We show the OD score and cell viability (line). The data are expressed as mean±SD. *p<0.001 vs. PBS, **p<0.001 vs. FW, ***p<0.05 vs. FW.