Children’s teeth that have not grown back after several months may be due to malnutrition, vitamin D deficiency, congenital hypothyroidism and other conditions. 1. Malnutrition: usually due to insufficient or disproportionate intake of nutrients, digestive dysfunction and other conditions. Patients often show symptoms such as weight loss, emaciation, reduced fat content, etc., while children are often characterized by developmental delays, which can also be manifested in children whose teeth have been missing for several months and have not yet grown out. 2. Vitamin D deficiency: infants and young children are mainly due to insufficient perinatal vitamin D reserves, insufficient sunlight, insufficient food supplementation and so on. Children often appear sweating, bone deformity, muscle relaxation and other symptoms, some infants and young children can also be manifested as cranial softening, funnel chest, delayed teething, and so on, so that children’s teeth fall out of a few months has not grown out of the situation. 3. Congenital hypothyroidism: usually due to the thyroid gland is not developed or underdeveloped and so on, the patient will often appear physiological function is low, intelligence disorders, metabolic disorders and growth retardation phenomenon, so the patient can also be manifested as children’s teeth fell out a few months have not grown out. It is recommended that if the child’s teeth have not grown out after several months, it is recommended to consult a doctor in time, to be evaluated by a specialist, to improve the relevant examinations and to give targeted treatment or therapy.