[[File:Cross sections of teeth intl.svg|thumb|300px|
1. Tooth
2. Enamel
3. Dentin
4. Dental pulp
5. cameral pulp
6. root pulp
7. Cementum
8. Crown
9. Cusp
10. Sulcus
11. Neck
12. Root
13. Furcation
14. Root apex
15. Apical foramen
16. Gingival sulcus
17. Periodontium
18. Gingiva
19. free or interdental
20. marginal
21. alveolar
22. Periodontal ligament
23. Alveolar bone
24. Vessels and nerves
25. dental
26. periodontal
27. alveolar through channel]]
A cusp is a pointed, projecting, or elevated feature. In , it is usually used to refer to raised points on the crowns of teeth.
The concept is also used with regard to the leaflets of the four . The mitral valve, which has two cusps, is also known as the bicuspid valve, and the tricuspid valve has three cusps.
In humans
A cusp is an occlusal or incisal eminence on a tooth.
canine tooth, otherwise known as
cuspids, each possess a single cusp, while
, otherwise known as
bicuspids, possess two each. Molars normally possess either four or five cusps. In certain populations the
molars, especially
, will possess a fifth cusp situated on the mesiolingual cusp known as the Cusp of Carabelli.
One other variation of the upper first premolar is the 'Uto-Aztecan' upper premolar. It is a bulge on the buccal cusp that is only found in Native American Indians, with highest frequencies of occurrence in Arizona. The name is not a dental term; it comes from a regional linguistic division of Native American Indian language groups.
Cusps on the molars of therian mammals
There are four main cusps found on the molars of the upper
dentition of
mammals.
Hypocone
The
hypocone is found on the distal lingual side of the tooth. It fits into the grooves of the lower dentition and is an
adaptation for the overall grinding and tearing of foods using the occlusal (chewing side) of the tooth surface during occlusion or
mastication (chewing). Its strength is due to the thickness of the
Tooth enamel which differs among species of hominids. The hypocone appears to have evolved independently more than twenty times in different mammal groups during the Cenozoic period.
Metacone
The
metacone is a cusp on the
molars of the upper
dentition in
hominids. It is found at the
Cheek distal area of the tooth. The crests between the cusps are
adaptations for slicing food during occlusion or
mastication (chewing).
Paracone
The anterior of the three cusps of a primitive upper molar that in higher forms is the principal anterior and outside cusp.
Protocone
The
protocone is founding the
molars of the upper
dentition in
Placental and
Marsupial vertebrates.
[Gavin Prideaux, "Systematics and Evolution of the Sthenurine Kangaroos" (April 1, 2004). UC Publications in Geological Sciences. Paper vol_146. http://repositories.cdlib.org/ucpress/ucpgs/vol_146 p.16] It is found at the mesiolingual area of the tooth. The crests between the cusps are
adaptations for slicing food during occlusion or
mastication (chewing).
See also
Bibliography
-
Ash, Major M.; Nelson, Stanley. Wheeler'S Dental Anatomy, Physiology and Occlusion, 8th edition.
