The clinical manifestation of dental fluorosis is characterized by chalky to brown plaques on the enamel erupting at the same time and, in severe cases, is complicated by parenchymal defects of the enamel. It is often clinically classified into chalky (mild), stained (moderate) and defective (severe) types according to their mild, moderate and severe severity. The following diseases may cause chalky to brown plaque on teeth: 1. Periodontal disease Periodontal disease is a disease of the supporting tissues of the teeth, including the gums, bone, periodontal ligament and alveolar bone due to inflammation , is one of the most common oral diseases and is a major cause of tooth loss. However, not all of these tissues are affected at the same time, depending on the severity and extent of local inflammation, periodontal disease can actually be divided into two major categories: gingivitis and periodontitis. 2, hereditary opalescent dentin Hereditary dentinogenesis imperfecta (hereditary dentinogenesis imperfecta), also known as hereditary opalescent dentin (hereditary opalescent dentin), is named because it has a family heredity and the teeth are translucent opalescent appearance. 3, tetracycline teeth Tetracycline is an antibiotic catalyzed by chrysomycin dehalogenated biosynthesis, low toxicity, as early as 1948 that began to be used clinically. 1950, foreign reports of tetracycline drugs cause tooth staining; then reported one after another tetracycline deposition in the teeth, bones and even nails, and can also cause enamel development. In this regard, domestic attention until the mid-1970s. 4, tooth hypersensitivity tooth hypersensitivity (tooth hypersensitivity), also known as hypersensitive dentine or dentine hypersensitivity, is a tooth in the external stimuli, such as temperature (cold, heat), chemical substances (acid, sweet) and mechanical action (friction or abrasion). The symptoms are characterized by rapid onset, sharp pain and short duration. Dental hypersensitivity is not an independent disease, but a symptom common to various dental diseases, and the peak age of onset is around 40 years old. 5, dental fluorosis Fluorosis, also known as dental fluorosis or enamel fluorosis (mottled enamel), is a regional disease and is the most common and prominent symptom in the early stages of chronic fluorosis. Dental fluorosis has been reported in all countries in the world. There are many fluorosis endemic areas in China, including chronic fluorosis areas in Northeast China, Inner Mongolia, Ningxia, Shaanxi, Shanxi, Gansu, Hebei, Shandong, Guizhou and Fujian. Fluorosis is related to people’s health and serious people suffer from fluorosis at the same time, so it should be paid great attention.