The main reasons why children are not teething at 8 months are as follows: First, affected by genetic factors, such as parents have backward dental development, the child will also have backward dental development by genetic factors, that is, the phenomenon of 8 months without teeth. Second, malnutrition, such as poor immune function of the child, often occurring digestive or respiratory diseases lead to the child’s nutritional absorption state abnormal, or the child’s spleen and stomach function and other causes of the child’s lack of nutrients, malnutrition caused by dental development backward, that is, 8 months no teeth. Third, the child has a special disease such as hypothyroidism or dwarfism, the child may also have no teeth at 8 months, need to be examined in detail in the hospital and given further treatment.