Effect of hydrogen-containing jelly on periodontal tissue

INTERVENTION: Hydrogen‐containing jelly group: Hydrogen‐containing jelly is swallowed without chewing three times a day (morning, noon, night) for 28 consecutive days. Hydrogen‐free jelly (placebo) group: Hydrogen‐free jelly (placebo) is swallowed without chewing three times a day (morning, noon, night) for 28 consecutive days. CONDITION: Periodontitis PRIMARY OUTCOME: Percentage of sites of bleeding on probing SECONDARY OUTCOME: Probing pocket depth, clinical attachement level, periodontal inflamed surface area: PISA, plaque control record: PCR, oxidative stress (d‐ROMs) and antioxidant capacity (OXY‐adsorbent test) of serum oxidative stress, lactate dehydrogenase of unstimulated saliva, cytokines (IL‐1 beta, IL‐6, IL‐10, IL‐17, and TNF‐alpha) levels of gingival crevicular fluid INCLUSION CRITERIA: 1. Persons over 70 years old 2. Persons who have more than 10 teeth 3. Persons with periodontitis