tooth

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tooth:

see teethteeth,
hard, calcified structures embedded in the bone of the jaws of vertebrates that perform the primary function of mastication. Humans and most other mammals have a temporary set of teeth, the deciduous, or milk, teeth; in humans, they usually erupt between the 6th and 24th
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Tooth

One of the structures found in the mouth of most vertebrates which, in their most primitive form, were conical and were usually used for seizing, cutting up, or chewing food, or for all three of these purposes. The basic tissues that make up the vertebrate tooth are enamel, dentin, cementum, and pulp (see illustration).

Structure of a toothenlarge picture
Structure of a tooth

Enamel is the hardest tissue in the body because of the very high concentration, about 96%, of mineral salts. The remaining 4% is water and organic matter. The enamel has no nerve supply, although it is nourished to a very slight degree from the dentin it surrounds. The fine, microscopic hexagonal rods (prisms) of apatite which make up the enamel are held together by a cementing substance.

Dentin, a very bonelike tissue, makes up the bulk of a tooth, consisting of 70% of such inorganic material as calcium and phosphorus, and 30% of water and organic matter, principally collagen. The rich nerve supply makes dentin a highly sensitive tissue; this sensitivity serves no obvious physiological function.

Cement is a calcified tissue, a type of modified bone less hard than dentin, which fastens the roots of teeth to the alveolus, the bony socket into which the tooth is implanted. A miscellaneous tissue, consisting of nerves, fibrous tissue, lymph, and blood vessels, known as the pulp, occupies the cavity of the tooth surrounded by dentin.

The dentition of therian mammals, at least primitively, consists of four different kinds of teeth. The incisors (I) are usually used for nipping and grasping; the canines (C) serve for stabbing or piercing; the premolars (Pm) grasp, slice, or function as additional molars; and the molars (M) do the chewing, cutting, and grinding of the food. Primitively the placentals have 40 teeth and the marsupials 50.

In therian mammals, probably because of the intricacies and vital importance of tooth occlusion, only part of the first (or “milk”) dentition is replaced. This second, or permanent, dentition is made up of incisors, canines, and premolars; as a rule only one premolar is replaced in marsupials. Although the molars erupt late in development and are permanent, that is, not replaced, they are part of the first, or deciduous, dentition.

tooth

One of a series of carved ornaments, typically a pyramidal shape or a four-petal flower, usually set in a concave molding band; used in the Romanesque and Gothic Revival styles. See also: Ornament

tooth

[′tüth]
(anatomy)
One of the hard bony structures supported by the jaws in mammals and by other bones of the mouth and pharynx in lower vertebrates serving principally for prehension and mastication.
(design engineering)
One of the regular projections on the edge or face of a gear wheel.
An angular projection on a tool or other implement, such as a rake, saw, or comb.
(graphic arts)
The coarse or abrasive quality of a paper or a painting ground that assists in the application of charcoal, pastels, or paint.
A paper texture that holds ink more readily.
(invertebrate zoology)
Any of various sharp, horny, chitinous, or calcareous processes on or about any part of an invertebrate that functions like or resembles vertebrate jaws.

tooth

1. In a paint film, a fine texture imparted either by pigments or by the abrasives used in sanding; this texture provides a good base for the adhesion of a subsequent coat of paint.
2. A dogtooth, 2.

tooth

1. any of various bonelike structures set in the jaws of most vertebrates and modified, according to the species, for biting, tearing, or chewing
2. any of various similar structures in invertebrates, occurring in the mouth or alimentary canal
3. any of the various small indentations occurring on the margin of a leaf, petal, etc.
4. any one of a number of uniform projections on a gear, sprocket, rack, etc., by which drive is transmitted
References in periodicals archive ?
The koalas, all male, had various degrees of tooth wear.
The study looked at tooth wear risk factors and found that those with frequent acidic food intake had higher levels of damage.
These common habits put excessive pressure on the temporomandibular joint and the surrounding muscles which can cause jaw pain, tooth wear, tooth sensitivity, broken or cracked teeth, and muscle spasms.
A number of indices for the clinical diagnosis of erosive tooth wear have been proposed, which more or less are modifications or combinations of the indices published by Eccles [1979] and Smith and Knight [1984].
BARTON replies: The main ingredient of the guinea pig's diet should be quality hay which contains the essential fibre needed for proper gut function and tooth wear.
They can include tooth wear or fracture, decay, erosion, toothbrush abrasion or genetic anomalies.
However we also ate a much rougher grittier diet and this caused tooth wear both on the surface and in between the teeth.
She is also working in the lab, where she will be participating in a number of research projects, before designing her own master's level project, which may deal with tooth wear in a mutant strain of mice.
There is convincing evidence from both home and abroad that the frequent consumption of sugary foods, fizzy drinks and fatty snacks are a cause of both tooth decay and tooth wear in teenagers.
In a first full volume on dental erosion, restorative dentists from Europe and the US consider such aspects as defining erosion and its links to tooth wear, diagnosis, the chemistry, extrinsic and intrinsic causes, children, dentine hypersensitivity, and restorative therapy.
ABSTRACT: We examined 56 anterior segments of mandibles from moose harvested from a declining population that was affected by tooth wear and breakage at higher rates than in moose elsewhere on the Seward Peninsula, Alaska.