It is normal for a 5-year-old girl to have 10 teeth in her jaw, and a 5-year-old girl may have more or fewer than 10 teeth in her jaw. When a child reaches about two and a half years of age, the milk teeth are basically fully erupted. If the child’s teeth have erupted normally and are not missing, a 5-year-old girl should have 20 milk teeth evenly distributed in the upper and lower jaws, with 5 milk mesial incisors, milk lateral incisors, intermaxillary teeth, the first molar, and the second molar in each of the two zones of the lower jaw; therefore, it is normal for a 5-year-old girl to have 10 teeth in the lower jaw. However, 5-year-old girls may have missing milk teeth or malformed milk teeth, and if one or two milk incisors are missing, the 5-year-old girl will have less than 10 teeth in her lower jaw; there are also some 5-year-old girls who have multiple teeth in their lower jaw, and they will have more than 10 teeth. Parents can take their children to the dental hospital in time when they find malformation or missing teeth in the lower jaw of 5-year-old girls.