Periodontal disease refers to chronic, non-specific and infectious diseases of the supporting tissues of the teeth, including the gum, periodontal membrane, alveolar bone and cementum. Gingivitis and periodontitis are the most common. Periodontal disease, along with dental caries, is one of the most common diseases in humans. In China, the prevalence of periodontal disease is obviously higher than that of caries. With the increase of age, the prevalence and severity of periodontal disease also increase gradually.