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. Although all 20 primary teeth usually appear by age 3, the pace and order of eruption varies. Oral care should begin soon after birth. Gums should be cleaned after each feeding. A moistened washcloth is ideal for this. You can begin brushing your child's teeth as soon as they appear. 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 (wisdom teeth).