Dental fluoride is usually applied once every 6 months to a year, but there are some differences between individuals, so it is recommended to consult a doctor for a clear diagnosis and set a specific time for fluoride application. Fluoride is an important treatment for preventing dental caries in children, in which fluoride can increase the degree of mineralization of the teeth to make the teeth, especially milk teeth, stronger, and can effectively prevent the erosion of external acidic substances and other irritants; and fluoride has a certain anti-bacterial effect, reducing the incidence of dental caries. Fluoride is usually applied once every 6 months to a year or so, and is suitable for children aged 3~6 years old; before fluoride application, oral cleaning is generally required; water should not be drunk within 1 hour after fluoride application, and food can be eaten within 2 hours; those who are allergic or hypersensitive to fluoride should not apply fluoride. Consult your physician for advice.