Eight-year-old children have not changed teeth may be due to physiological phenomena, retained milk teeth, blocked teeth and other reasons. 1. Physiological phenomenon: may be due to the child’s own genetics, their own late development and other reasons, are normal phenomena. 2. Retained milk teeth: refers to the phenomenon that the inherited permanent teeth have erupted, but the milk teeth have not fallen out, which can appear in eight-year-old children have not yet changed their teeth. It may be caused by rickets, abnormal root resorption of milk teeth. 3. Obstructed teeth: refers to the teeth that have passed the period of eruption and still fail to erupt in the jawbone tissue. It may be caused by supernumerary teeth, infection and other reasons. It can hinder the growth of newborn teeth, and thus the phenomenon of an eight-year-old child who has not yet changed his teeth can occur. There may be other reasons why an eight year old child has not yet replaced his teeth, so it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, and then give targeted treatment or treatment under the guidance of the doctor.