tooth (tth) [ L. dens; Gr. odous ]
1. any of the hard calcified structures set in the alveolar processes of the mandible and maxilla for mastication of food. In humans, there are two sets of teeth (dentes[TA]), deciduous and permanent. Each tooth consists of three parts: the crown (see corona dentis), the neck (see cervix dentis), and the root (see radix dentis). The solid part includes dentin, forming most of the tooth and resembling true bone; enamel, a very hard inorganic substance, covering the crown; and cementum, covering the root. In the center is the soft pulp (see pulpa dentis). See also dentition. 2. a structure resembling the tooth of an animal.
Schematic cross section of an anterior (left) and a posterior (right) tooth in the maxilla.

abutment tooth, one selected to support a bridge on the basis of the total surface area of a healthy attachment apparatus. See also
abutment (def. 2).
accessional teeth, the molar teeth of the permanent dentition, so called because they do not supplant any deciduous predecessors in the dental arch. Cf. succedaneous teeth.
anatomic teeth, artificial teeth that duplicate the anatomic forms of natural teeth.teeth that have prominent pointed or rounded cusps on the masticating surfaces and are designed to occlude with the teeth of the opposing denture or natural dentition.
ankylosed tooth, submerged t.
anterior teeth, the incisor and canine teeth, which are in the anterior parts of the dental arches. Called also labial or morsal teeth.
artificial tooth, one fabricated for use as a substitute for a natural tooth in a prosthesis, usually made of porcelain or resin. See also denture.
auditory teeth, auditory teeth of Huschke, dentes acustici.
tooth of axis, dens axis.
baby teeth, deciduous teeth.
bicuspid teeth, premolar teeth.
buccal teeth, posterior teeth.
canine tooth, the tooth immediately lateral to the lateral, or second, incisor; it has a long conical crown and the longest, most powerful root of all the teeth. Called also canine, cuspid, cuspid t., and dens caninus[TA].
carnassial tooth, a large molar or premolar of a carnivore, specialized for shearing and tearing.
cheek teeth, posterior teeth.
cog tooth of malleus, spur of malleus.
conical tooth, peg t.
connate tooth, geminate t.
corner tooth, the third incisor on either side of each jaw in the horse. Called also corner.
cross-bite teeth, artificial posterior teeth designed to permit positioning of the modified buccal cusps of the upper teeth in the fossae of the lower teeth.
cross-pin teeth, artificial teeth in which the pins are inserted horizontally.
cuspid tooth, canine t.
cuspless tooth, any tooth deprived of a cusp; particularly an artificial tooth designed without cuspal prominences on the occlusal surface.
deciduous teeth, the 20 teeth of the first dentition, which are shed and replaced by the permanent teeth. They begin to calcify at about the fourth month of fetal life, and near the end of the sixth month they all have begun to develop. The first incisors appear at about the age of 6 1/2 months; they are followed by the second incisors 1/2 month later; and, within 1 1/2 months, by the maxillary incisors. The deciduous molars begin eruption a 1 year, and the deciduous canines approximately 4 months later. All the deciduous teeth are expected to erupt by the time the child is 2 1/2 years of age. The deciduous dentition formula (one side) is as follows:


where I =incisor; C =canine; M =molar. Symbol D. Called also baby, milk, primary, or temporary teeth; deciduous, first, primary, or temporary dentition; and dentes decidui[TA].

Models of deciduous teeth (A); deciduous canine (B); and deciduous second molar (C).
diatoric teeth, artificial teeth with holes in their bases into which the denture base material flows and, when processed, attaches the teeth to the base. Called also pinless teeth.
drifting tooth, wandering t.
embedded tooth, one that is unerupted because of lack of eruptive force.
tooth of epistropheus, dens axis.
eye tooth, colloquial term for a canine tooth of the upper jaw.
Fournier teeth, Moon teeth.
fused teeth, partial or complete fusion of two or more individual teeth.
geminate tooth, a tooth with a single root and root canal, but with two completely or incompletely separated crowns, resulting from invagination of a single tooth germ, causing incomplete formation of two teeth. Called also connate t.
Goslee tooth, an interchangeable artificial tooth attached to a metal base.
hag teeth, upper medial incisors that are widely separated.
Horner teeth, incisor teeth that are horizontally grooved owing to a deficiency of enamel.
Hutchinson teeth, a tooth abnormality seen in congenital syphilis, in which the permanent incisors have a screwdriverlike shape, sometimes with notching of the incisal edges or depressions in the labial surfaces above the cutting edge. Called also Hutchinson incisors and screwdriver teeth.
impacted tooth, one prevented from erupting by a physical barrier. See also unerupted t.
incisor tooth, either of the two most frontal teeth in each jaw, one on either side of the midline; it has a long root and is adapted for cutting. Symbol I. Called also incisor and dens incisivus[TA].
labial teeth, anterior teeth.
malacotic teeth, teeth that are soft in structure and are abnormally susceptible to caries.
malposed tooth, a tooth out of its normal position.
mandibular teeth, the teeth of the mandible, or lower jaw.
maxillary teeth, the teeth of the maxilla, or upper jaw.
metal insert tooth, an artificial tooth, usually of acrylic resin, containing an inserted ribbon of metal or a cutting blade in the occlusal surface, with one edge exposed; sometimes used in removable dentures.
milk tooth, predeciduous t.neonatal t.deciduous t.
molar teeth, the most posterior teeth on either side in each jaw, totaling 8 in the deciduous dentition (2 on each side, upper and lower), and usually 12 in the permanent dentition (3 on each side, upper and lower). They are the grinding teeth, having large crowns with broad chewing surfaces. The upper molars characteristically have 4 major cusps and three roots. The lower first molars characteristically have 5 cusps, and the remaining lower molars 4 cusps. Normally all lower molars have two roots. The third molars (“wisdom teeth”) are often malformed, but when developed normally their crown and root form corresponds in general with neighboring molars in the same jaw. Symbol M. Called also molars and dentes molares[TA].
molar tooth, third, the tooth most distal to the medial line on either side in each jaw, so called because it is the last of the permanent dentition to erupt, usually at the age of 17 to 21 years. Called also wisdom t., third molar, dens molaris tertius[TA], and dens serotinus[TA alternative].
Moon teeth, small, domed first molars observed in patients with congenital syphilis.
morsal teeth, anterior teeth.
mottled teeth, see under enamel.
mulberry tooth, mulberry molar.
natal tooth, predeciduous t.
neonatal tooth, one that erupts within the first month of life. Called also milk t.
nonanatomic teeth, a term applied to artificial teeth the occlusal surfaces of which are especially designed on the basis of engineering concepts, without regard to the features of natural teeth.
peg tooth, peg-shaped tooth, one having a conical form, whose sides converge or taper together incisally, instead of being parallel or diverging mesially and distally; a condition frequently observed in the maxillary lateral incisor. Called also conical t.
permanent teeth, the 32 teeth of the second dentition, which begin to appear in humans at about 6 years of age. The first molars appear first, followed by the mandibular central and lateral incisors, maxillary central incisors, maxillary lateral incisors, mandibular canines, first premolars, second premolars, maxillary canines, second molars, and third molars. They take their position posterior to the deciduous teeth and erupt in succession, whenever the jaws grow sufficiently to accommodate them. Exfoliation of the deciduous teeth is brought about by resorption of their roots, and the succedaneous permanent teeth take their place. The permanent dentition formula (one side) is as follows:

where I =incisor; C =canine; P =premolar; M =molar. Called also dentes permanentes[TA] and permanent or secondary dentition.

Models of permanent teeth (A); permanent canine (B); and permanent first molar (C).

pink tooth of Mummery, internal tooth resorption (def. 1).
pinless teeth, diatoric teeth.
posterior teeth, the premolar and molar teeth, which are in the posterior parts of the dental arches. Called also buccal or cheek teeth.
predeciduous tooth, any tooth present at birth, which may be normal in all respects or may represent a hornified epithelial rootless structure, found on the gingivae over the crest of the ridge before eruption of the deciduous teeth. Called also dentia praecox, milk or natal t., and predeciduous dentition.
premature teeth, deciduous teeth that erupt prior to the end of the third month of life, or permanent teeth that erupt prior to the end of the fourth year of life. Called also dentia praecox and precocious or premature dentition. See also predeciduous teeth.
premolar teeth, the permanent teeth between the canines and the molars; there are two on either side in each jaw. The upper premolars are bicuspid and the lower have from one to three cusps. Premolars are succedaneous to the deciduous molar teeth. Symbol P. Called also dentes premolares[TA], premolars, bicuspids, and bicuspid animals other than humans, the teeth that succeed the deciduous molars regardless of the number to be succeeded.
primary teeth, deciduous teeth.
pulpless tooth, a tooth from which the pulp has been extirpated.
rake teeth, teeth that are widely separated.
rootless teeth, dentinal dysplasia.
sclerotic teeth, teeth that are hard in structure and resistant to caries.
screwdriver teeth, Hutchinson teeth.
shell tooth, a condition characterized by dysplasia of the dentin, associated with essentially normal enamel, thus resulting in an extremely large pulp chamber and root canal that give the affected tooth the appearance of a shell.
snaggle tooth, a tooth out of proper line with the others.
stomach tooth, a canine tooth of the mandible.
straight-pin teeth, artificial teeth in which the pins are inserted vertically.
submerged tooth, a deciduous tooth, usually a second mandibular molar, that has undergone resorption and has become ankylosed to the bone, thus preventing its exfoliation and subsequent replacement by a permanent tooth; it appears to be submerged below the level of occlusion in relation to the adjacent permanent teeth. Called also ankylosed t.
succedaneous teeth, successional teeth, the permanent teeth that have deciduous predecessors in the dental arch. Cf. accessional teeth.
superior teeth, the teeth of the upper jaw, or maxilla.
supernumerary teeth, supplemental teeth, natural teeth in excess of the number normally present in the jaw.

Supernumerary teeth in cleidocranial dysplasia.

temporary teeth, deciduous teeth.
tube teeth, artificial teeth having a vertical, cylindrical aperture from the center of the base up into the body of the tooth, into which a pin may be placed or cast for attachment of the tooth to the denture base.
Turner tooth, enamel hypoplasia of a single tooth, most commonly one of the permanent maxillary incisors or a maxillary or mandibular premolar, resulting from local infection or trauma. Called also Turner hypoplasia.
unerupted tooth, one that failed to erupt; the presence of multiple unerupted permanent teeth is sometimes referred to as pseudoanodontia. See also embedded t. and impacted t.
vital teeth, teeth to which the nerve and vascular supply is intact.
wandering tooth, a tooth that drifts from its normal position in the dental arch. Called also drifting t.
wisdom tooth, third molar t.
wolf tooth, a vestigial first premolar tooth sometimes present in the jaw of a horse.
zero degree teeth, artificial teeth which have no cusp angles in relation to the horizontal on their occlusal surfaces.