A brief definition and description of the various anatomical features of a normal tooth, and its supporting structures, include the following:
A. Dental Structures:
1. Anatomical crown - That portion of the tooth which is covered by enamel.
2. Clinical crown - That portion of the tooth which is visible in the mouth. The clinical crown may, or may not, correspond to the anatomical crown, depending on the level of the tooth's investing soft tissue, and so may also include a portion of the anatomical root. As can be seen from this description, the clinical crown may be an ever changing entity throughout life, while the anatomical crown is a constant entity.
3. Anatomical root - That portion of the tooth which is covered with cementum.
4. Clinical root - That portion of the tooth which is not visible in the mouth. Again, the clinical root is an ever changing entity, and may, or may not, correspond to the anatomical root.
Note: In the dental literature, the modifying terms "clinical" and "anatomical" are not often used with crown or root, but the intended meaning is most often "anatomical" and so will be used in this manner hereafter.
5. Enamel - The hard, mineralized tissue which covers the dentin of the ana' tomical crown of a tooth. It is the hardest living body tissue, but is brittle, especially when not supported by sound underlying dentin.
6. Dentin - The hard tissue which forms the main body of the tooth. It surrounds the pulp cavity, and is covered by the enamel in the anatomical crown, and by the cementum in the anatomical root. The dentin constitutes the bulk, or majority, of the total tooth tissues, but because of its internal location, is not directly visible in a normal tooth.
7. Cementum - The layer of hard, bonelike tissue which covers the dentin of the anatomical root of a tooth.
8. Cervical line - The identifiable line around the external surface of a tooth where the enamel and cementum meet. It is also called the cemento-enamel junction or CEJ. The cervical line separates the anatomical crown and the anatomical root, and is a constant entity. Its location is in the general area of the tooth spoken of as the neck or cervix.
9. Dentino-enamel junction or DEJ - The internal line of meeting of the dentin and enamel in the anatomical crown of a tooth.
10. Pulp - The living soft tissue which occupies the pulp cavity of a vital tooth. It contains the tooth's nutrient supply in the form of blood vessels, as well as the nerve supply.
11. Pulp Cavity - The entire internal cavity of a tooth which contains the pulp. It consists of the following entities:
a. Pulp canal(s) - That portion of the pulp cavity which is located in the root(s) of the tooth, and may also be called the root canal(s).
b. Pulp chamber - The enlarged portion of the pulp cavity which is found mostly in the anatomical crown of the tooth.
c. Pulp horns - The usually pointed incisal or occlusal elongations of the pulp chamber which often correspond to the cusps, or lobes of the teeth.
B. Supporting Structures:
1. Alveolar process - The entire bony entity which surrounds and supports all the teeth in each jaw member.
2. Alveolus (Plural - alveoli) - The bony socket, or portion of the alveolar process, into which an individual tooth is set.
3. Periodontal ligament (membrane) - The fibrous attachment of the tooth cementum to the alveolar bone.
4. Gingiva (Plural - gingivae) - The "gum" or "gums", or the fibrous tissue enclosed by mucous membrane that covers the alveolar processes and surrounds the necks of the teeth.
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