Children’s teeth begin forming before birth. As early as 4 months, the first primary (or baby) teeth to erupt through the gums are the lower central incisors, followed closely by the upper central incisors. By age 3, most children will have grown all 20 of their primary teeth in varying pace and order of tooth eruption. Permanent teeth begin appearing around age 6, starting with the first molars and lower central incisors. This process continues until approximately age 21. Adults have 28 permanent teeth, or up to 32, including the third molars (or wisdom teeth).