Among all mammals, the tooth consists of a crown, the portion visible in the mouth, and one or more roots embedded in a gum socket. The portion of the gum surrounding the root, known as the periodontal membrane, cushions the tooth in its bony socket. The jawbone serves as a firm anchor for the root. The center of the crown is filled with soft, pulpy tissue containing blood vessels and nerves this tissue extends to the tip of the root by means of a canal. Surrounding the pulp and making up the greater bulk of the tooth is a hard, bony substance, dentin. The root portion has an overlayer of cementum, while the crown portion has an additional layer of enamel, the hardest substance in the body. Most nonmammalian vertebrates do not have the outer layer of enamel on their teeth, but instead have a substance known as vitrodentine, similar to dentine, though much harder.
Proper diet is necessary for the development and maintenance of sound teeth, especially sufficient calcium, phosphorus, and vitamins D and C. The most common disorder that affects the teeth is dental caries (tooth decay). A widely accepted explanation of the process of tooth decay is that salivary bacteria convert carbohydrate particles in the mouth into lactic acid, which attacks the enamel, dentin, and, if left untreated, the pulp of the teeth. Regular cleansing and semiannual dental examinations (see dentistry ) are important in preventing dental caries and gum disorders. Fluoridation of public water supplies and use of fluoride toothpastes also help prevent caries. In the study of fossil remains done in paleontology and physical anthropology, teeth are the most frequently found remains, a testament to their high mineral content and resistance to deterioration over time. See dentition .
See P. S. Ungar, Mammal Teeth: Origin, Evolution, and Diversity (2010).
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.
See more Encyclopedia articles on: Anatomy and Physiology
Browse By Subject
- Earth and the Environment +-
- History +-
- Literature and the Arts +-
- Medicine +-
- People +-
- Philosophy and Religion +-
- Places +-
- Australia and Oceania
- Britain, Ireland, France, and the Low Countries
- Commonwealth of Independent States and the Baltic Nations
- Germany, Scandinavia, and Central Europe
- Latin America and the Caribbean
- Oceans, Continents, and Polar Regions
- Spain, Portugal, Italy, Greece, and the Balkans
- United States, Canada, and Greenland
- Plants and Animals +-
- Science and Technology +-
- Social Sciences and the Law +-
- Sports and Everyday Life +-