ENAMEL
The hardest tissue
The crown is covered with enamel, the hardest substance in the body. If it is damaged, it has very little ability to repair itself.
Explore the layersTHE ANATOMY OF A TOOTH
Hard outside,
alive inside.
A tooth looks like one solid thing. It is built in layers.
Explore the layers
96%mineral in adult enamel
- Enamel protects
- Dentine supports
- Pulp keeps it alive
- Three layers, one tooth
A hard mineral shell protects a living core of blood vessels and nerves, and a thin cushion ties the root to the jaw. Knowing the layers makes a tooth easier to understand, and to draw. An independent informational guide, not dental advice.
Updated
THE SHORT ANSWER
Crown above,
root below.
A tooth has a crown above the gum and a root below it.
Inside, it has several distinct layers.
DENTINE AND PULP
The living core
Under the enamel, dentine surrounds the pulp chamber, which holds blood vessels, nerves and connective tissue. Dentine is sensitive to touch and temperature.
Draw one
ROOT
Held by a cushion
On the root, dentine is covered by cementum, and a membrane called the periodontal ligament cushions the tooth and attaches it firmly to the jawbone.
How it is heldGeneral information only, not medical advice. For advice about your own health, speak to a doctor, pharmacist or other qualified health professional.
LAYER BY LAYER
What is each
layer made of?
Pick a part of the tooth. The bar shows roughly how hard and mineral-rich it is, from soft tissue to the hardest tissue in the body.
Anatomy for general interest, not dental advice. If you have tooth pain or a problem with your teeth, see a dentist.
TWO NUMBERS WORTH KNOWING
Tiny crystals,
tightly packed.
One figure on what enamel is made of,
one on how its crystals are arranged.
96%
Mineral share of adult enamel
Adult enamel is as much as 96% mineral, about 0.5% organic material and around 3.5% water. Immature enamel, by contrast, is about half organic material.
ENAMEL · CHARLES UNIVERSITY
≈ 1,000
Crystals in each enamel prism
Enamel prisms are bundles of about 1,000 hydroxyapatite crystals, each up to 1 mm long but only about 50 nanometres wide, running from the dentine out to the surface.
CRYSTALS · CHARLES UNIVERSITY
The NHS explains that tooth decay starts when bacteria form a sticky layer called plaque that damages the tooth surface over time, and that decay can eventually reach the soft pulp in the middle of the tooth.
SKETCH A TOOTH IN SECTION
Four outlines,
one tooth.
A cross-section is the clearest way to show the layers. Work from the outside in, using the anatomy above as your guide.
Draw the outer shape
Sketch a molar-like crown above a line for the gum, then one or more roots tapering down into the jaw.
Add the enamel cap
Draw a second line just inside the crown only. Enamel covers the crown; on the root, the outer layer is cementum instead.
Shade the dentine
Fill the space between enamel and pulp with a light tone. Dentine forms the bulk of the tooth, in the crown and the root.
Hollow out the pulp
Draw a central chamber with thin canals running down each root, where blood vessels and nerves enter.
HOW A TOOTH IS HELD
Not glued in,
slung in place.
A tooth is not fused to the jaw. The root's cementum layer is connected to the dentine by collagen fibres, and the periodontal ligament around it cushions the tooth and attaches it firmly to the jawbone.
Humans grow two sets of teeth: 20 primary teeth and 32 permanent teeth, although not everyone develops all four wisdom teeth. The same layers, enamel, dentine, pulp and cementum, appear in both sets.
Questions
Questions people ask
What is the hardest part of the body?
Tooth enamel. The MSD Manual describes it as the hardest substance in the body, and Charles University teaching notes call it the hardest tissue in the human body.
Can enamel grow back?
The MSD Manual says that although enamel is very hard, if it is damaged it has very little ability to repair itself.
Why can teeth feel cold or touch?
The MSD Manual says dentine, the layer under the enamel, is sensitive to touch and to temperature changes, and the pulp at the centre contains nerves.
What is the pulp?
The soft centre of a tooth. It contains blood vessels, nerves and connective tissue, which reach it through the root canals.
What holds a tooth in the jaw?
The periodontal ligament, a membrane around the root's cementum layer, cushions the tooth and attaches it firmly to the jawbone.