Children should have fillings for the following reasons: First, when the front teeth of the milk teeth are severely missing or prematurely lost, they cannot form clear pronunciation, causing difficulties in verbal communication and affecting the aesthetics, which will make the child have an inferiority complex. Second, the deeper cavities of milk teeth are easy to retain food debris, soft scale, so that the number of cariogenic bacteria continues to grow, resulting in the emergence of new permanent teeth caries, and affect the service life of teeth. Third, when chronic periapical inflammation occurs in milk teeth, it can affect the development of permanent tooth embryo, enamel underdevelopment and so on, and it will also cause difficulty in the eruption of permanent teeth, inducing malocclusion. After the formation of residual roots and crowns, the sharp edges of the teeth can rub the mucous membrane of the lips and cheeks, forming ulcers and preventing chewing and eating. Fifth, large caries will cause repeated infection of mucous membrane, causing children’s body temperature to rise.