Effects of Slightly Acidic Electrolyzed Water on Oral Pathogens and Human Gingival Fibroblasts

Abstract

In previous reports, slightly acidic electrolyzed water (SAEW) produced by electro-disintegration of 2-6% HCl solution exhibited antibacterial effects similar to those of strongly acidic electrolyzed water. The purpose of this study was to investigate the bactericidal effects of SAEW at different concentrations against key oral pathogens and the cytotoxicity to adult human gingival fibroblasts (HGF). Streptococcus mutans (ATCC25175), Aggregatibacter actinomycetemcomitans (ATCC29522), Porphyromonas gingivalis (W83, ATCC33277) and Prevotella intermedia (ATCC25611) were selected for the bactericidal tests. HGF was obtained from the gingival tissue around extracted adult human teeth. Each genus of bacteria (initial concentration at 1×10^6 cell/ml) was incubated with SAEW for one minute at room temperature and their survival rates were measured by colony counting. Cytotoxicity of SAEW against HGF was studied by cell proliferation assessment with Alamar Blue assay. The results demonstrated that SAEW concentration over 25% had complete bactericidal effects on all tested bacteria. Compared with distilled water, undiluted SAEW showed significant inhibition of HGF proliferation. However, such effects were not found when the concentration was lower than 50%. The cytotoxicity (LD50) of SAEW determined by Alamar Blue assay was 70-80w/w%. These results suggested that 50% SAEW has ideal bactericidal ability without significant cytotoxicity.