Your child's primary teeth generally make their appearance when he or she is 6 or 7 months old, though it can occur as early as birth. There are 20 primary teeth, followed by 32 permanent teeth that will eventually replace them. Your child should have all his or her primary teeth at age 3 and will keep them until age 5 or 6, when they begin to loosen and fall out. This process usually lasts until the child is 12 or 13.