It is a relatively normal physiological phenomenon that infants do not have teeth yet at 8 months. There is some individual variation in the timing of tooth eruption, which is related to many factors, such as the infant’s physical condition, nutritional status, gender, place of birth, race, genetic factors, and some other objective factors. The development of teeth is a rough indicator of skeletal maturity, and the speed and timing of the eruption of baby teeth can also reflect the growth and nutritional status of the baby. Therefore, after the birth of a baby, every slight change will affect the parents’ heart. If some babies of the same age have already started teething, parents may be anxious in this case. In fact, there is no need for parents to be overly worried, because as long as the baby erupts between 4-10 months, it is considered normal, and most babies start to erupt gradually 6-7 months after birth. If the baby is more than 1 year old and the teeth have not erupted, it is important to consider the presence of delayed eruption. For delayed eruption, it is important to note that it may be caused by vitamin D deficiency or calcium deficiency on the one hand, and congenital ectodermal dysplasia on the other. Parents are advised to take their infants to the hospital in a timely manner to determine the cause of the problem and then treat the cause.