Oral inflammatory diseases,involved in multiple oral subspecialties,cause pain in dental pulp,periodontal tissues,mucous membranes and other parts in oral cavities.These diseases are mainly related to microbial imbalance and inappropriate immune response of the organism.Hydrogen has become a research hotspot because of its anti-inflammatory and antioxidant functions,and its therapeutic effect has been confirmed in a variety of systemic inflammatory disease models.Among oral inflammatory diseases,research about hydrogen is mainly focused on periodontitis with high incidence rate and peri-implant inflammation,a current hot issue.At the same time,research has also been conducted on periodontitis,mucosal diseases,and trauma under special conditions.Hydrogen exhibits promising prospects in relevant research and application due to its selective reducing action,which is highly connected with the occurrence and development of oral inflammatory diseases.This review introduces the basic and clinical research of hydrogen in oral inflammatory diseases and also the relevant mechanism.