Effects of hydrogen rich water and pure water on periodontal inflammatory factor level, oxidative stress level and oral flora: a systematic review and meta-analysis.

Background: Hydrogen rich water (HRW) was used as an auxiliary treatment for periodontitis and peri-implantitis due to its good antioxidant properties. However, the stability of artificially added active hydrogen was far less than that of pure natural active hydrogen, which greatly reduced active hydrogen molecules number in HRW. Meanwhile, the effect of HRW was relatively slow. Finally, long-term drinking of HRW may cause abnormal liver function. Hence, this study sought to summarize and analyze the effects of HRW on oral inflammation and oral flora in various studies to determine whether HRW can be used to inhibit dental plaque formation and aliviate oral inflammation. Methods: Randomized controlled trials (RCTs) of HRW and pure water (PW) in the treatment of periodontal diseases published before March 2022 in the PubMed, Web of science, EMBASE, Cochrane, China Knowledge Resource Integrated, Wanfang, and Weipu databases were searched. Changes in the inflammatory factor levels, oxidative stress response, and oral flora were summarized and used as outcome indicators. The quality of included studies was assessed by Cochrane risk of bias assessment tool, and the standardized mean differences (SMD) and the 95% confidence intervals (CIs) were calculated using Review Manager 5.3. Results: In total, 17 studies, comprising 304 subjects, were included in this meta-analysis. Among them, 5 studies had a high risk of bias, and the rest had a certain risk of bias, thus, the total risk of bias was medium to low. The levels of interleukin (IL)-1β (SMD =-0.73; 95% CI: -1.29 to -0.18; P=0.009), tumor necrosis factor alpha (SMD =-2.51; 95% CI: -3.56 to -1.46; P<0.00001), IL-6 (SMD =-1.31; 95% CI: -1.96 to -0.67; P<0.0001), 8-hydroxyguanosine (SMD =-1.61; 95% CI: -2.35 to -0.87; P<0.0001), and reactive oxygen metabolites (SMD =-0.49; 95% CI: -0.91 to -0.06; P=0.02) in the HRW group decreased significantly, while the glutathione peroxidase level increased (SMD =2.5; 95% CI: 1.85 to 3.15; P<0.00001). Additionally, HRW was shown to effectively inhibit oral pathogenic bacteria activity (SMD =-0.91; 95% CI: -1.16 to -0.66; P<0.00001). Conclusions: HRW effectively inhibits the inflammatory reaction, oxidative stress level, and bacterial proliferation activity in patients with periodontal disease.