Fluoride application for children is more effective in preventing caries. The physiological local structure of children’s teeth is different from permanent teeth, and the chemical reactivity of milk teeth with the outside world is more active than permanent teeth, which is easily affected by the outside environment. If the external environment is acidic, such as after eating too much sugar, the food will stick to the teeth and produce acidic substances after a long time, which will easily lead to demineralization after the chemical change between the tooth surface and the external world. Children’s milk teeth are very easy to decay, but if you can make good use of the characteristics can make the milk teeth increase the effect of anti-caries. Such as the use of fluoride may enhance the resistance, so children coated with fluoride is relatively good.