The most common disease of teeth is caries. Food is an important factor for the occurrence of caries, and the said food mainly refers to sugar, among which sucrose is the most cariogenic sugar, white sugar and brown sugar are mainly composed of sucrose, but glucose, fructose and maltose in the diet also have certain cariogenicity, while lactose is less cariogenic. The sugar we get from diet every day, besides lactose in milk, endogenous sugar in fruits and vegetables, there are some foreign sugar, that is, free sugar. This above distinction is very important in the dietary advice because lactose and endogenous sugar are less harmful to teeth, while free sugar is the main causative factor for caries occurrence. Foods with starch as the main component, such as potatoes, steamed buns, rice, etc. are not caries-causing, but foods made of refined flour processed and mixed with sugar, such as cookies, bread, cakes, etc., are as caries-causing as sugar. Among young children, fruit-flavored sugary drinks are the biggest dental health hazard and often the causative factor for rampant caries. There is also the addition of extra sugar to dairy products, which is also a major cause of dental caries in children.