Generally speaking it is normal to start replacing teeth at around 6 years of age until all milk teeth are replaced at around 12 years of age, but there are many factors that affect tooth replacement, such as gender, body type, dietary habits and so on. The general order of tooth replacement in children is as follows: Generally it is around the age of 6 years old when tooth replacement starts, the lower side of the teeth are replaced first, then the upper side of the teeth are replaced, the front teeth are replaced first, then the side teeth are replaced. Generally speaking children will lose all their milk teeth and have all their permanent teeth erupted by the age of about 12. During tooth replacement parents should encourage their children to eat more fiber-rich, rough foods to increase chewing strength. Parents also need to pay extra attention to their children’s oral hygiene during the tooth replacement period and urge their children to learn the correct way to brush their teeth. Parents should pay attention to the retention of milk teeth during the tooth replacement period. If there is any retention of milk teeth, you should consult a doctor immediately to identify the cause of the problem and take appropriate treatment.