Periodontal disease is another common disease in the human oral cavity besides dental caries. It is the most widespread chronic infectious disease in the population. Periodontal disease is a constant threat to periodontal health and oral health. And it has a close relationship with the whole body health. Currently 80-97% of adults in China suffer from periodontal disease of varying degrees, which is the first cause of tooth loss in adults. So what is periodontal disease? What are the causes? How can it be prevented and treated? Periodontal disease is a chronic inflammatory disease that invades the gums and periodontal tissues, and is a destructive disease characterized mainly by the formation of periodontal pockets and inflammation of the pockets’ walls, resorption of alveolar bone and gradual loosening of teeth, which leads to tooth loss. The disease is mostly caused by plaque, tartar, food impaction, poor restorations, bite wounds, etc. The gums become inflamed and swollen, while aggravating the plaque accumulation and expanding from supragingival to subgingival. Due to the characteristics of the subgingival microecological environment, a large number of virulent periodontal pathogenic bacteria breed in the subgingival plaque, which aggravates and extends the inflammation of the gums, leading to the formation of periodontal pockets and alveolar bone resorption, resulting in periodontitis. The main pathogenic factor of periodontal disease is dental plaque. The bacteria in plaque is the initiating factor of periodontal disease, so removing plaque and preventing or reducing plaque reaccumulation are the main measures to treat periodontal disease and prevent recurrence. At the same time, it is also an important method to prevent and treat dental caries. Mechanical method to control plaque is an important measure to control periodontal disease and dental caries more conveniently and effectively. Brushing is an important self-care method to remove plaque and keep the oral cavity clean. Proper brushing method is an important guarantee to maintain oral health. Modified Bass brushing method is a clinically recommended brushing method for more effective plaque removal. During brushing, be sure to brush all sides of the teeth, especially the inconvenient areas. Flossing and interdental brushing can be supplemented. Develop good oral hygiene habits to achieve more effective brushing. Inflammation caused by the invasion of bacteria or toxins into the dental pulp located in the center of the tooth. Spontaneous, paroxysmal pain is the main symptom. It is often clinically classified as reversible pulpitis, irreversible pulpitis, pulp degeneration and pulp necrosis. It is mostly treated by removing the pulp. The vast majority of periapical lesions, especially inflammatory ones, are secondary to pulp disease. In the case of periapical lesions, the pulp can also be affected. Oral ulcers, the most common clinically recurrent oral ulcers, also known as recurrent mouth sores, are lesions of the oral mucosal capillaries caused by viruses or bacteria, – a recurrent oral mucosal disease. It is characterized by recurrent attacks, burning pain, and a pattern of periodic recurrence. It can also cause a variety of complications. The disease can occur at any age, but is more common in young adults. It has a tendency to heal on its own. There is no clear cause for this disease. The causes are complex and are related to mental stress, insomnia, digestive disorders, constipation and overexertion. In women, the disease may develop due to endocrine cyclical changes before menstruation. Some people think it is an autoimmune disease. Based on the above causative factors, most of the preventive measures are to adjust the diet, abstain from spicy, wine, coffee and other stimulating foods, avoid mental tension, maintain emotional stability, adhere to physical exercise, and enhance the immunity of the body. Maintain oral hygiene and so on. The treatment of the disease is: strengthening nutrition and adjusting immunity. For local ulcers to prevent infection, systemic application of antibiotics, oral local medication, soda water or chlorhexidine mouthwash gargle. The ulcer surface is coated with Chinese medicinal preparations of “remove rot and clear the stomach, remove rot and create muscle”, etc. Oral health is an important part of human health. Oral health and the quality of life have an inseparable relationship as a whole. A person with healthy and white teeth looks confident in all aspects of social life. A person with bad teeth, full of tartar and bad breath will not only be annoying, but will also have low self-esteem. Poor oral hygiene can cause dental caries and periodontal disease, destroy chewing function, cause indigestion, affect absorption and induce systemic diseases. Periodontal disease and loss of teeth brings unaccustomed and inconvenient to wear dentures. With the development of social economy and the improvement of people’s health level, people’s demand for oral health is growing, how to maintain oral health, how to strengthen people’s awareness of the importance of oral health care, and strengthen oral knowledge publicity and education is particularly important.