Teeth first begin to appear between the 4th and 18th month of age. By the time your child reaches 3, they should have all their primary teeth in place. Permanent teeth will begin to come in at approximately 6 years of age.
Permanent teeth come up under the primary teeth and cause their roots to slowly dissolve.
All permanent teeth should be in by the age of 13. Unlike the permanent dentition, The primary dentition has no premolars. Dental care should start early for your child. Naturally, at first you'll have to care for their teeth. Begin cleaning the baby teeth as soon as you see the first one in place.