Teeth (singular tooth) are small, calcified, whitish structures found in the jaws (or mouths) of many vertebrates that are used to break down food. Some animals, particularly carnivores, also use teeth for hunting or for defensive purposes. The roots of teeth are embedded in the Mandible bone or the Maxillary bone and are covered by gums. Teeth are made of multiple tissues of varying density and hardness.

Teeth are among the most distinctive (and long-lasting) features of mammal species. Paleontologists use teeth to identify fossil species and determine their relationships. The shape of an animal's teeth is related to its diet. For example, plant matter is hard to digest, so herbivores have many molars for chewing and grinding. Carnivores, on the other hand, need canines to kill prey and to tear meat.

Mammals are diphyodont, meaning that they develop two sets of teeth. In humans, the first set (also called the "baby", "milk", "primary", and "deciduous" set) normally starts to appear at about six months of age, although some babies are born with one or more visible teeth, known as neonatal teeth. Normal tooth eruption at about six months is known as teething and can be painful.

Some animals develop only one set of teeth (monophyodont) while others develop many sets (polyphyodont). Sharks, for example, grow a new set of teeth every two weeks to replace worn teeth. Rodent incisors grow and wear away continually through gnawing, which helps maintain relatively constant length. The industry of the beaver is due in part to this qualification. Many rodents such as voles (but not mice) and guinea pigs, as well as rabbits, have continuously growing molars in addition to incisors.

Dental trauma refers to trauma to the face, mouth, and especially the teeth lips and periodontium. The study of dental trauma is called dental traumatology.

Noun

tooth (plural teeth)

1. A hard, calcareous structure present in the mouth of many vertebrate animals, generally used for eating.
2. A sharp projection on the blade of a saw or similar implement.
3. A projection on the edge of a gear that meshes with similar projections on adjacent gears, or on the circumference of a cog that engages with a chain.
4. (botany) A pointed projection from the margin of a leaf.

• (structure in the mouth): bicuspid, canine, cuspid, incisor, premolar, molar
• See also Wikisaurus:tooth

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