Effect of slightly-acidic electrolyzed water to oral microorganisms and fibroblast

Objectives: The slightly-acidic electrolyzed water (SAW), one of the electrolyzed oxidizing water, is pH from 5.0 to 6.5. This water includes hypochlorous acid efficiently and has more antibacterial activity than sodium hypochlorite. In this study, the effects of SAW to oral microorganisms and human gingival fibroblast were examined in comparison with chlorhexidine gluconate (CHX). Methods: The antibacterial activity of SAW was examined to 8 species of oral microorganisms. The microorganism suspension adjusted to 10⁷ cfu/ml was treated with SAW from 10 to 30 ppm of the effective chlorine concentration until five minutes. After inoculation and culture, the surviving microorganisms were counted. The antibacterial activity for bacterial biofilm was also examined in comparison with CHX (0.2%). Furthermore the gingival fibroblast treated with SAW or CHX was observed by confocal laser microscope. Also the cell proliferation activity of the treated fibroblast was measured. In addition, the adhesion of bacteria to the fibroblast and the cell proliferation activity were examined after addition of the bacteria treated by SAW or CHX. Results: SAW showed strong antibacterial activity for all of oral microorganisms treated in 20 ppm for 10 seconds. Compared to planktonic bacteria, the activity was week in bacterial biofilm. However, the activity showed almost same level as CHX. The cytotoxicity for the gingival fibroblast of SAW was extremely weaker than CHX. In addition, the bacterial adhesion to the fibroblast was decreased by treatment with SAW. The cell proliferation activity of the fibroblast was lowered by addition of living bacteria, but did not change with the bacteria treated by SAW. Conclusion: The slightly-acidic electrolyzed water had superior antibacterial activity for oral microorganisms and low cytotoxicity to human gingival fibroblast. These results suggested that the slightly-acidic electrolyzed water was extremely useful as antibacterial water in the field of dentistry.