There is no clear clinical data to indicate how old a child is suitable for dental fluoride application. Generally, the need for fluoride application can be determined when the child is about 6 months old, and routine fluoride application can be done when the child is about 3 years old. 1. Dental fluoride refers to the application of highly concentrated fluoride to the surface of the teeth to form a protective layer, thus preventing tooth decay. The commonly used fluoride coating materials include fluoride foam, fluoride gel and fluoride varnish, and fluoride varnish is mostly used in the clinic. Meanwhile, according to the clinical information, it is recommended that babies should have their teeth examined by a doctor around 6 months after the first tooth erupts to determine whether fluoride is needed. 2. When the baby reaches the age of 3, it can be routinely fluoridated for better prevention of dental caries. Generally, fluoride should be applied 2~4 times a year and once every 3~6 months, and some babies need to be evaluated by the doctor to choose the time of fluoride application. It is important to note that no food should be eaten within 2 hours after fluoride application and some water should be consumed within half an hour, and flossing or brushing should be avoided within 4~6 hours. Parents are advised to bring their babies to the doctor for regular dental checkups according to the clinical recommendations, and to cooperate with the doctor if fluoride application is needed.