There may be two aspects of physiological and pathological factors, which can be judged according to the presence or absence of other manifestations: I. Physiological factors 1. Individual differences: most babies start teething between 4-10 months of age, but the early and late teething has great individual differences. Some babies have teething before 4 months of age, some babies start teething only at 12 months, as long as the health and normal development are within the normal range, do not worry too much; 2, dietary habits: food chewing is conducive to dental growth. The late addition of supplementary food, food is too fine, etc. will lead to the lack of chewing stimulation of the gums, resulting in late teething time. However, too hard food is also not suitable for babies who are not teething and cannot fully chew. Therefore, the baby’s diet should ensure that the coarse and fine, balanced nutrition. Second, pathological factors 1, nutrient deficiency: calcium and vitamin D deficiency may also lead to late teething. It is recommended that the mother can reasonably supplement calcium and vitamin D under the guidance of the doctor, and at the same time, the daily diet should also be appropriately supplemented with calcium-rich foods to ensure that the baby has a comprehensive diet and healthy development. 2, physical diseases: rickets, hypothyroidism, benign brittle bone disease, etc. can also cause late teething. Therefore, the baby mother can always pay attention to whether the baby has abnormal symptoms, early detection and early treatment.