Figure 8: Ten minutes transition in ORP of saliva before and after mouthcleaning with hydrogen-water for the aged person. Note: An initial ORP value of the saliva in the 66-year-old female was 180 mV. Hydrogen-water (hydrogen, 960 μg/L; ORP, –440 mV) was used for the 1-minute washing mouth. ORP decreased until 3 minutes after 1-minute washing with hydrogen-water, but ORP increased from 3 minutes to 5 minutes and reached to a steady-state value. It was stable in the state of ORP of saliva after washing. ORP: Oxidation-reduction potential.