Teeth are made up of various layers, from the hard outer enamel to the soft inner pulp. Understanding the layers of the teeth can help us understand specific parts, such as the anatomic crown of the tooth, and the role they play in the mouth.
What Is the Anatomic Crown?
The crown is the surface of the tooth that lies above the gumline, and it contains three different dental layers: enamel, dentin and pulp. Each layer serves a distinct purpose within the tooth structure. Just like the crunchy middle, creamy coating and crispy shell of a chocolate-covered peanut, the layers of the anatomic crown can be easily identified.
Three Layers of an Anatomic Crown
Enamel is the thin, most mineralized portion of the tooth. At 96 percent minerals, enamel is the hardest structure in the human body. BBC Focus Magazine points out that hydroxyapatite, the major mineral in teeth, scores a five on the Mohs scale for measuring the hardness of minerals – making it harder than the pennies in your pocket! (Take a look at this National Park Service geology chart for more comparisons.) The surface of the enamel ends at the cemento-enamel junction, the portion of the tooth where the exposed crown stops and the root starts. Much like the hard candy coating of that chocolate peanut, the enamel protects the soft inner part of the tooth from harm.
Dentin is the middle layer of the tooth structure, forming the bulk of the tooth. Dentin is made up of hollow tubules that contain fluid in them which carry signals (for sensations like pain or temperature changes) from the enamel to the pulp, where the nerves of your teeth are located. For this reason, exposed dentin can be a cause of sensitive teeth, according to theAmerican Dental Association (ADA). Dentin is more easily affected by bacterial invasion, and like a layer of chocolate, it can wear away once the outer enamel coating is destroyed by acids, breakage or decay.
Inside the core of the tooth, notes the ADA, the blood and nerve supply resides in a small chamber called the pulp chamber. Like the peanut inside the candy-coated chocolate, the pulp is completely surrounded by the dentin. Since the pulp holds the vital components, like nerves and blood vessels, strong sensitivity or pain can flare up if it is exposed to bacteria or the tooth is broken, according to the University Hospital of Copenhagen. Inflammation of the pulp is also one of the main reasons for root canal treatment.
Anatomic vs. Clinical Crown
When your dentist talks about replacing or repairing a crown, they might not always mean the anatomic portion. The clinical crown is the tooth structure that can be seen when looking into your mouth, while the anatomic portion also includes tooth surface hidden by the gumline. As the teeth are erupting, or growing into place, the entire anatomic crown might not be visible, but when the gum tissue covers all portions of the root and all of the enamel-covered portion of the crown is visible, the anatomic and clinical crowns are one in the same.
The role of the anatomic crown is an important one. It contains all of the chewing surface of your teeth, as well as the protruding tooth area that your tongue strikes against to help you articulate words. The nerves contained in the pulpy cores of your teeth warn your body of heat, cold and pain, and the hard enamel keeps bacteria from entering into your teeth.
If you're curious about your tooth structure, you can ask your dentist. And if you munch on any chocolate-covered peanuts, be sure to brush afterward.