There are several reasons for the slow teething of children: First, genetics, the early and late teething has a certain relationship with genetic factors, parents late teething as a child, the child’s teething time will also be relatively late, different sexes also differ in the time of teething, boys are generally later than girls teething time. Second, nutritional factors, healthy teeth and protein, calcium, phosphorus, fluorine, vitamins and other nutrients are closely related, insufficient protein intake can cause delayed tooth eruption, adequate calcium, phosphorus, fluorine helps baby teeth calcification, adequate vitamin D is extremely important to the development of teeth, if the baby’s diet is not balanced, the lack of these nutrients in the body can cause the baby late teething. Third, disease causes, when the baby suffers from rickets or hypothyroidism, will also cause the baby late teething. Four, premature babies and low weight babies will also appear slow teething phenomenon, as long as the baby before one year old teething is normal, if more than one year old not teething, we must go to the hospital to find the cause.