Infants’ milk teeth usually erupt between 4 and 10 months after birth, most often starting to erupt at 6 months of age. If the milk teeth do not erupt after 12 months, it is called delayed eruption. The time and order of eruption varies greatly among individuals and is related to genetics, endocrine and food traits. Common causes include: 1) rickets, which is caused by vitamin D and calcium deficiency, should be supplemented with vitamin D and calcium, and outdoor activities should be increased in the morning and evening. 2) hypothyroidism. Regardless of the cause of delayed eruption of milk teeth, you should consult a doctor promptly, make a clear diagnosis and actively treat the problem.