Periodontal disease not only destroys the supporting tissues of teeth, causing gum redness, bleeding and tooth loss, but also poses a threat to systemic health because the bacterial components and cellular products in the oral cavity can easily spread to nearby or distant organs through the ulcerated surface of periodontal pockets, leading to or exacerbating the development of certain systemic diseases, such as coronary heart disease, diabetes and lung infections, which seriously endanger human health. 1, patients with acute heart attack and coronary arteriosclerosis have significantly poorer oral hygiene than the normal population. The incidence of coronary heart disease in patients with periodontitis is 20% higher than that of the normal population. 70% higher than that of the general population in men under 50 years old with periodontitis or without teeth. The incidence of fatal coronary heart disease and cardiac arrest in patients with severe alveolar bone resorption is two times and three times higher than that of the normal population, respectively. 2. The risk of preterm delivery and low birth weight babies for pregnant women with severe periodontitis is 7.5 times higher than that for pregnant women with normal periodontal disease, which is greater than the effect of smoking and alcohol consumption on low birth weight babies. Preterm birth and low birth weight babies are mainly caused by maternal periodontal infection interfering with the cytokines and hormones that are automatically regulated by pregnancy. 3. Severe periodontitis is one of the risk factors for elevated blood glucose in diabetic patients. Patients with insulin-dependent diabetes mellitus with severe periodontitis have significantly poorer glycemic control than patients without periodontal disease. If periodontal infection is effectively controlled, the response of the patient’s body tissues to insulin can be restored to normal, and the insulin required for its blood glucose control is subsequently reduced, which indicates that the patient’s glucose metabolism has been improved. 4, epidemiological survey shows that the chance of lung infection and reduced lung function in those with poor oral hygiene is 1.77 times of those with good oral hygiene. With the change and development of the understanding of the relationship between periodontal disease and systemic health, some multifactorial diseases (such as periodontitis, arthritis, cardiovascular disease, etc.) and their interrelationships have been further understood. Periodontitis can be a risk factor for certain diseases or may share risk factors with certain diseases. Periodontitis can be well managed by controlling and removing plaque. Therefore, the prevention and treatment of periodontitis is important for maintaining general health and reducing major diseases. The treatment of periodontitis is not only limited to the preservation of the affected teeth, but also to the better control of the infection to protect the organism. If the existing dental disease is actively treated, the teeth with severe and poor prognosis of periodontal disease should be extracted as soon as possible. Antimicrobial agents should be applied prophylactically to prevent complications and temporary bacteremia in some susceptible patients (e.g. patients with wind heart disease, diabetes, kidney disease) before doing complex periodontal examination and treatment.