Methods: O－-water was prepared using the AOE-750（Oxy Japan Corporation, Japan.）and its effectiveness in killing Streptococcus sobrinus, Porphyromonas gingivalis, Prevotella intermedia, Actinobacillus actinomycetemcomitans, Fusobacterium nucleatum and C. albicans in pure culture was evaluated. Each oral microorganism (104－108 CFU/ml) was exposed to several concentrations of O－-water (pH 2.0, 2.25, 2.5, 2.75 or 3.0) at room temperature or 37 degrees for 15 sec to 24 hr. After incubation, 100 µl samples were transferred into 900 µl trypticase soy broth and diluted in a 10-fold series. Each 100 µl of sample was plated on to an agar plate, spread evenly with a Conrage stick, and cultured. At the end of the culture number of CFUs was determined. As a control, distilled water, acetic acid water (pH 2.5) and hydrochloric acid water (pH 2.5) were also used.
Results: Exposure to O－-water for between 5 to 10 min resulted in a bactericidal effect against cariogenic and periodontopathic bacteria. Treatment at 37 degrees was more effective than that at room temperature. O－-water showed no significant fungicidal effect on C. albicans.
Conclusion: The results suggest that O－-water has an antibacterial effect on cariogenic and periodontopathic bacteria and that it could be used as a disinfectant in reducing bacterial contamination of dental instruments.