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 their eruption varies.
Permanent teeth begin appearing around age 6, starting with the first molars and lower central incisors. At the age of 8, you can generally expect the bottom 4 primary teeth (lower central and lateral incisors) and the top 4 primary teeth (upper central and lateral incisors) to be gone and permanent teeth to have taken their place. There is about a one to two year break from ages 8-10 and then the rest of the permanent teeth will start to come in. This process continues until approximately age 21.
Adults have 28 permanent teeth, or up to 32 including the third molars (or wisdom teeth)