Teeth

Dive Deeper
A frontal view of the jawbone and skull shows how the permanent teeth are developing underneath the baby teeth. This skull comes from a 6 1/2 year old. (Image Credit: Henry Gray, 1918, Public Domain)

Why do people get two sets of teeth – baby teeth and adult teeth?

Humans have two sets of teeth because a child’s jaw is too small to fit the adult teeth. Plus, the second set of teeth lets accidents and poor dental hygiene have fewer long term consequences.

Teeth start as buds in the seventh week after conception. Around nine weeks after conception, each bud splits into a small, dormant tooth bud that will develop into a permanent tooth, and a larger bell-shaped tooth that will develop into a baby tooth. Next, the jaw bone forms around the baby tooth and permanent tooth, holding them in place. Then the tooth grows by adding layers of dentin inside the tooth and enamel outside the tooth. Finally, the baby teeth start to poke out of the gum, starting roughly six months after birth.1 Most children have their full set of 20 baby teeth by age 2. Permanent teeth form inside the jaw bone through early childhood. When children shed their baby teeth, only the crown and the uppermost part of the root fall out. The permanent teeth use the same artery and bone socket that the baby teeth used.2