We often refer to different parts and properties of your teeth when talking about oral health or cosmetic dentistry. We try to explain this as we go along, and hopefully it’s clear, but it’s also important to talk about the structure of your teeth in detail to make sure it’s clear what we’re talking about.

Crowns and Roots

The tooth is often described as two different parts: the crown and the root. The crown is the part of the tooth that’s generally outside of your bone and gums, the visible portion of the tooth.

The root is the part of the tooth that’s normally below your gums, what serves to support and anchor your teeth.

The two parts are connected by a narrower part of the tooth that is called the neck of the tooth.


The enamel is the outer covering of your tooth crown. It’s a unique material in the body because it’s almost entirely made up of minerals. It’s 96% mineral content, mostly made up of hydroxyapatite. Hydroxyapatite gives your teeth their whiteness, as well their hardness and strength.


Dentin is the layer of tooth that’s under the enamel. It’s not as hard, not as white, and not as mineralized as your enamel. Dentin is only about 70% mineral, which has both benefits and limitations. Being less mineralized, dentin has a little more “flex” to it than enamel, which helps your teeth, too, because it allows them to absorb very strong bite force without breaking.

But once the enamel is weakened or gone, dentin may be more vulnerable to breaking, and, especially, decay from bacteria.


The pulp is the soft, living structure inside your tooth. It’s sometimes described as the tooth “nerve.” It conveys tooth pain to your body, and it’s what gets bruised when you have a darkened tooth.

It’s important to protect your pulp from oral bacteria, which can thrive inside the tooth once they make it there. When we are treating this type of infection,we use a procedure called a root canal.

A toothache is often described as “pulpitis,” and it can be caused by tooth trauma or by an infection. Dentin also has tiny tubes built into it that convey sensation into the pulp. This can lead to short-lived pain in the pulp in response to heat and cold. Opening up of these tubes is what leads to sensitivity following teeth whitening.


Cementum is a part of your tooth you should never see. It is to your tooth root what enamel is to the crown: the outer covering. Cementum has a rough surface that helps it bond to your gums and the periodontal ligaments that hold your teeth in place. Cementum is, unfortunately, very vulnerable to decay. It’s only 45% mineral, so once receding gums expose your cementum, you may be at risk for root cavities that can grow very quickly. Gum disease treatment can help prevent exposure of your cementum.

If you have questions about any dental symptoms you might be experiencing or treatments we propose, we’re happy to answer any questions you may have. We want to make sure you understand your oral health and treatment options.

For an appointment with a Las Vegas dentist who is happy to explain everything, please call the office of Dr. James B. Polley at (702) 873-0324.