The application of hyperbaric oxygen in medicine is progressing faster, and for the treatment of oral diseases, hyperbaric oxygen has achieved remarkable efficacy. 1, periodontal disease Periodontal disease is a chronic inflammatory disease that invades the gums and periodontal supporting tissues, it is the main cause of tooth loss in adults, and its infecting bacteria are mainly anaerobic bacteria. Periodontitis should be promptly treated with hyperbaric oxygen during the acute attack, twice a day, 7 days as a course of treatment, 2~3 consecutive courses of treatment. 2, oral mucosal white spots oral mucosal white spots are white plaques or patches on the oral mucosa, which cannot be diagnosed as any other diseases by clinical and histopathological methods. The World Health Organization (WHO) classifies it as precancerous lesion. Hyperbaric oxygen can regulate immunity, anti-inflammatory and anti-swelling effects, which can promote aerobic metabolism and local tissue repair. Oral mucosal white spots should be treated with hyperbaric oxygen as early as possible. 3, oral submucosal fibrosis Oral submucosal fibrosis or oral submucosal fibrosis (OSF) is a chronic progressive oral mucosal disease with cancer tendency, which is often clinically manifested as burning pain, painful irritating food, progressive mouth opening restriction, swallowing difficulty and other symptoms. OSF is mainly found in Hunan and Taiwan provinces in China, and is classified as precancerous by WHO. Epidemiological investigation shows that long-term chewing of betel nut is the main causative factor of OSF. Factors such as eating chili peppers, smoking and drinking alcohol can aggravate submucosal fibrosis. Hyperbaric oxygen can increase the blood oxygen level, improve local ischemia and hypoxia, and promote the formation of neovascularization and the establishment of collateral circulation in the lesion area. Once a day, ten times a course of treatment, usually 1~2 courses of treatment.