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

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Sources

Sadler, Thomas W. Medical Embyrology. 14th ed., 2019.
Moore, Keith, TVN Persaud, and Mark G. Torchia. The Developing Human, Clinically Oriented Embryology. 10th ed. Philadelphia: Elsevier, 2016.

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All images and illustrations on The Voyage of Life were reviewed by credentialed scientists for accuracy.

Medical art animation was used to provide a schematic representation of fetal development, with some features, including timing, not to scale. The animation was chosen as an ethically uncompromised guide to fetal development. There are many real human images at each developmental age showing the most accurate fetal forms throughout development. A concerted effort was made to use images and material in which the human embryo or fetus did not undergo any known harm.

Page last updated on October 21, 2022

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Teeth