Hey everyone, this is Ben with RegisteredNurseRN.com and in this video I'm going to talk about the anatomy of teeth. But first I want to ask you a quick question that many people get wrong. Your teeth are considered bones.
True or false? The answer is false. Although teeth and bones do have a similar appearance, they also have important differences.
Therefore, anatomists do not classify teeth as bones. Now as you look at the anatomy of a tooth, you will see that it consists of three major parts. The crown, the neck, and the root. The crown is the visible portion of the tooth above the neck and extending out of the gums.
Just as you have a crown on your head, you can think of the tooth's crown as the head or top of the tooth. It is covered in a hard protective layer called enamel, which covers the dentin and underlying pulp chamber and pulp. The neck of the tooth, also called the cemento-enamel junction or cervical line, allows for the attachment of the gingiv or gums to the teeth. And it represents the area where the crown's enamel layer meets the cementum layer covering the tooth's root. You can usually see the visible line of the neck when you look at an extracted tooth.
Finally, you have the root. of the tooth, which is the larger portion extending down from the neck or cemento-enamel junction to the root's apex, and it is secured to a socket of alveolar bone in the mandible or maxilla. Now, some teeth, such as the incisors, have just one root, while others, such as the molars, can have two or three roots. And just as the crown is covered in a protective layer of enamel, the root is covered in its own protective layer called cementum. which covers the dentin and its underlying root canal and pulp.
So the teeth have those three major parts, crown, neck, and root, but these parts are comprised of four major tissue types. You have enamel, cementum, dentin, and pulp. Enamel, which makes up the hardened outer layer of the crown, does not contain living tissue such as vessels, nerves, or cells. Instead, it is mostly comprised of a dense arrangement of minerals, such as hydroxyapatite, which are formed into tiny prison rods that run in a wave pattern perpendicular to the tooth's surface, though they can also run parallel near the tooth's neck. Although enamel is the hardest substance in the human body, it can be dissolved after prolonged exposure to acid produced by a dental plaque which can eventually lead to the development of cavities.
And acidic foods can also temporarily soften enamel, which is why dental health professionals sometimes recommend waiting up to 30 to 60 minutes to brush your teeth after you eat acidic foods. Another type of tissue found in the tooth is cementum, which is the hardened bone-like tissue that covers the tooth's root. It's formed by cells called cementoblasts, and cementum has a light yellow appearance, as you can see, and it consists of a lower mineral concentration than both enamel and dentin, making it softer in comparison to those tissues.
Now the periodontal ligament surrounds and attaches to the cementum of the tooth and anchors it to its socket in the alveolar process of the jaw bones. Cementum is also one of the four tissues that make up the periodontium. which surrounds and supports the teeth.
The other three being the gingiv or gums, the periodontal ligament, and the alveolar bone proper. A third type of tissue found in the tooth is called dentin or sometimes dentine. And this is another hardened tissue and it is deep to both the crown's enamel and the root's cementum.
It is formed and maintained by cells called odontoblasts. As you can see, Denton accounts for most of the tooth's mass, and it contains a mineral content of around 70%, which makes it harder than cementum and even bone, yet softer than enamel. Dentinal tubules run through the Denton in a parallel pattern, originating at the pulp cavity and ending just short of the enamel or cementum. And these tubules transfer nutrients from the pulp to the Denton.
and contain an odontoblast process which maintains the dentin. Because these tubules originate at the pulp of the tooth, which contains all the vessels and nerves, any damage to the enamel or gums can affect these tubules which may result in tooth pain or sensitivity. And the border where the dentin meets the enamel is called the dentino-enamel junction or DEJ for short.
And the border where the dentin meets the cementum is called the dentino-cemental junction or DCJ for short. And finally the dental pulp is the last type of major tissue that makes up the tooth and this is a soft tissue that is located within the pulp cavity of each tooth. The pulp cavity has two main parts the narrow root canal of the root or roots and the larger pulp chamber located in the crown. The root canal originates at a small hole in the apex of the root or roots called the apical foramen, and it travels up the root of the tooth and then expands into a larger pulp chamber within the crown of the tooth.
The pulp's tissue consists of odontoblast vessels and nerves, which together supply the tooth's nutrition, sensation, and immune defense, as well as the secretions that maintain the dentin. And finally, just as you have four main tissues that make up the teeth, you also have four types of teeth in your mouth. The incisors, the canines, which are also called cuspids, the premolars or bicuspids, and the molars. And I'll talk more about those in my next video.
Okay, that wraps up this video over the anatomy of the teeth. And you can take a free quiz on our website by clicking the link in the description or comment section below. In addition, we have an entire playlist of anatomy videos that you might want to check out.
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