The chance of caries in the milk teeth of 3-year-old children is relatively high, and it varies from person to person, especially for children who like to eat milk at night or do not have the habit of brushing their teeth. Children’s milk teeth may also occur caries, especially for children who like to eat at night, as well as not timely oral care children, will lead to bacteria and food accumulation on the surface of the child’s teeth, the emergence of tooth decay and caries, if the child’s milk teeth are not well developed, may cause the surface of the teeth to appear some of the developmental deficiencies. So parents usually let the children to establish some knowledge of oral hygiene, as far as possible to avoid children to eat night milk, usually pay attention to oral hygiene, can effectively avoid the occurrence of dental caries.