In the biological world, the oral cavity is a very important organ and the loss of teeth is tantamount to the loss of life. For us, oral diseases make many people feel the pain of losing their teeth and being unable to chew. For a long time, there has been a popular saying that “toothache is not a disease, but a pain that really kills you”. But in fact, toothache is not only a disease, but also has a relationship with systemic diseases. There are five main diseases in oral cavity, including caries, periodontal disease, dental and maxillofacial malformation, maxillofacial tumor and maxillofacial trauma. Caries is a very common oral disease. In China, the prevalence of caries among 5-year-old children reaches 66%, the prevalence among 12-year-old children drops to 28.9%, the prevalence among 35-44-year-old adults rises to 88.1%, while the prevalence among 65-74-year-old people is as high as 98.4%. The prevalence of periodontal disease is also as high as 80-97%. Nearly half of our adults suffer from periodontitis, and the rate of bleeding gums among 35-44 year olds also reaches 77.3%. The prevalence of dental and maxillofacial malformations in children is 70%, and the prevalence of skeletal malformations and cleft lip and palate is 5% and 1.8%, respectively. Periodontal diseases, which have a high incidence, are closely related to cardiovascular diseases, diabetes, and pregnancy abnormalities. Cardiovascular disease, a major killer of human health, is also increasingly being linked to oral health. The bacteria that cause periodontitis can infect cardiovascular tissue through the bloodstream. Today there are even laboratory studies that have found that once oral bacteria enter the bloodstream, they can attach themselves to heart valves and cause disease. Moreover, the corresponding cytokines produced by periodontal disease can cause the walls of blood vessels to thicken, causing narrowing of the coronary arteries (heart vessels) and affecting heart health. Periodontal disease can cause bacteria to enter the body’s blood circulation, which activates the immune response. The cytokines produced in the immune response are often lethal to normal cells as well. In the pancreas, too many cytokines may then cause damage to the cells responsible for insulin production, and a decrease in this type of cell predisposes to diabetes. Periodontal disease and diabetes are causal, with the risk of periodontal disease 2.9 times higher than normal in diabetics with poor glycemic control and 1.56 times higher in well-controlled patients; poor glycemic control is four times higher and complications three times higher in diabetics with periodontal disease than in those without periodontal disease. Periodontal disease also triggers pregnancy abnormalities that will lead to miscarriage. Pregnant women with periodontal disease are 4.28 times more likely to give birth to a premature baby than normal; and 5.28 times more likely to give birth to a low birth weight baby. Periodontal disease in pregnant women may also affect the development of the baby’s heart and brain. Therefore, it is recommended that women preparing for pregnancy should have an oral examination and should pay more attention to their oral health during pregnancy. Oral diseases may also cause respiratory diseases. Eighty percent of all cases of aspiration pneumonia are related to oral bacteria. Oral disease is also strongly associated with neurological disorders. According to statistics, patients with less than 25 teeth will be 50% more likely to have a stroke than normal people. Missing teeth will lead to memory loss and increase the incidence of dementia. The development of gastrointestinal diseases may also be affected by oral diseases such as ulcerative diseases and Helicobacter pylori. And the roughness of food due to missing teeth may also cause an increase in the incidence of esophageal cancer. In people’s habitual thinking, the difficulty in chewing caused by missing teeth will affect the patient’s ability to eat and lead to a thin body. However, the opposite is true. Missing teeth make people feel less full, which is not conducive to eating control and can lead to obesity. Oral diseases not only make many people feel the pain of losing their teeth and being unable to chew, but their pathogenic bacteria can also cause or aggravate gastric diseases, diabetes, cardiovascular and cerebrovascular diseases and joint diseases and complications, seriously endangering the health of the whole body. It also affects the function of the heart, lungs, kidneys and other important organs. The World Health Organization put forward ten criteria for health many years ago, one of which is very important is clean teeth, no caries, no pain, normal gum color and no bleeding. Therefore, it is even more important for us to maintain oral health to improve the quality of life. If the following conditions occur, we should pay attention to them: suffering from some chronic diseases such as diabetes, heart disease, or having a family history of some chronic diseases, recently being very busy at work and having decreased resistance of the whole body; having cavities, tartar, and having bad breath frequently; having bleeding or red and swollen gums frequently, having pockets between gums and teeth; having loose teeth easily or feeling weak in biting often; experiencing mouth ulcers for more than two weeks that cannot healing. When these conditions occur, it means that dental health is not optimistic, and you need to review whether you have bad habits, such as brushing your teeth less than twice a day, not brushing your teeth before going to bed, smoking a lot or preferring to eat sugary foods or foods with high fat content. Only by changing these bad habits can you improve your health. For daily oral hygiene, the most important thing is to use proper brushing and flossing. Make sure to use fluoride toothpaste, especially for children, as fluoride toothpaste plays an important role in preventing and treating dental caries in children. The goal of maintaining oral hygiene is “8020”, which means that 80-year-olds should have at least 20 healthy teeth. At the same time, our social security system should also provide more investment in this area.