It is normal for a baby to have only 19 milk teeth if it is caused by the 20th milk tooth not fully erupting. However, if there are only 19 teeth after full eruption, they are missing teeth. A normal child should have 20 milk teeth. Generally, the first milk teeth will gradually grow out around 6~8 months after birth, and all milk teeth should fully erupt until 31 months of development. If a baby has only 19 milk teeth at the age of 2~3 years, it is generally considered that the number of missing teeth is caused by the last tooth not fully erupted, which is a normal physiological phenomenon. When the baby is more than 3~4 years old and still has only 19 milk teeth, it is not a normal phenomenon in growth and development, and congenital tooth loss should be considered. It is recommended to go to the hospital in time for dental radiographs, which can observe the specific number of teeth in the alveolar bone and determine whether there is any pathological disease. The number of baby teeth should be judged according to the growth and development time. If oral disease exists, it should be treated as soon as possible.