Children’s teeth are forming while still in the mother’s womb. Around 4 months after birth, the first primary (or baby) teeth to erupt through the gum tissue are the lower central incisors, followed shortly thereafter by the upper central incisors. The rate and pace of tooth shedding and eruption can vary from person to person however all 20 primary teeth usually appear by age 3.
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).