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In
mammal Mammals (from Latin language, Latin , 'breast') are a group of vertebrate animals constituting the class (biology), class Mammalia (), and characterized by the presence of mammary glands which in Female#Mammalian female, females produce milk ...
ian oral anatomy, the canine teeth, also called cuspids, dog teeth, or (in the context of the upper jaw) fangs, eye teeth, vampire teeth, or vampire fangs, are the relatively long, pointed
teeth A tooth (plural teeth) is a hard, calcification, calcified structure found in the jaws (or mouths) of many vertebrates and used to Mastication, break down food. Some animals, particularly carnivores, also use teeth for hunting or for defensive p ...
. They can appear more flattened however, causing them to resemble incisors and leading them to be called ''incisiform''. They developed and are used primarily for firmly holding food in order to tear it apart, and occasionally as weapons. They are often the largest teeth in a mammal's mouth. Individuals of most species that develop them normally have four, two in the upper jaw and two in the lower, separated within each jaw by incisors; humans and dogs are examples. In most species, canines are the anterior-most teeth in the
maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone A bone is a Stiffness, rigid tissue (anatomy), tissue that constitutes part of the vertebrate skeleton in animals. Bones protect the var ...
ry bone. The four canines in humans are the two maxillary canines and the two mandibular canines.


Details

There are four canine teeth: two in the upper (maxillary) and two in the lower (mandibular) arch. A canine is placed laterally to each lateral incisor and mesial to the premolars. They are larger and stronger than the incisors, and their roots sink deeply into the bones, and cause well-marked prominences upon the surface. They are the only teeth in dentition with a single cusp, their crowns are roughly triangular from mesial view and trapezoidal in buccal view. The crown is large and conical, very convex on its labial surface, a little hollowed and uneven on its
lingual
lingual
surface, and tapering to a blunted point or cusp, which projects beyond the level of the other teeth. The root is single, but longer and thicker than that of the incisors, conical in form, compressed laterally, and marked by a slight groove on each side. The lingual surface also presents two depressions on either side of the surface separated by a ridge in between; these depressions are known as mesial and distal lingual fossae.


Eruption

In humans, the upper canine teeth (popularly called eye teeth, from their position under the eyes) are larger and longer than the lower, and usually present a distinct basal ridge. Eruption typically occurs between the ages of eleven and twelve years for upper canines and between nine and ten years for lower canines. Upper deciduous canines also known as the baby tooth, typically erupt between ages of sixteen and twenty-two months and sheds between ten and twelve years. Lower deciduous canines typically erupt between ages of seventeen and twenty-two months and sheds between nine to twelve years


Developmental defects

Transposition (positional interchange of two adjacent teeth) is a development defect that most commonly found in the permanent canine, with the maxillary being more commonly seen than mandibular. The upper canine frequently transposed with the first premolar whilst the lower canine transposed with the lateral incisor. Occasionally canines are congenitally missing.


Maxillary canine morphology

From a facial aspect, maxillary canines are approximately one millimetre narrower than the central incisor. Their mesial aspects resemble the adjacent lateral incisors, while their distal aspects anticipate the first premolars. They are slightly darker and more yellow in color than the other anterior teeth. From a lingual aspect, they have well developed mesial and distal marginal ridges and a well-developed cingulum. A prominent lingual ridge divides the lingual aspect in half and creates the mesial and distal lingual fossae between the lingual ridge and the marginal ridges. From a proximal aspect, they resemble the incisors, but are more robust, especially in the cingulum region. Incisally, they are visibly asymmetrical, as the mesial incisal edge is slightly shorter than the distal incisal edge, which places the cusp slightly mesial to the long axis of the tooth. They are also thicker
labiolingually
labiolingually
than mesiodistally. Because of the disproportionate incisal edges, the contacts are also asymmetrical. Mesially, the contact sits at the junction of the incisal and middle third of the crown, while distally, the contact as more cervical, in the middle of the middle third of the crown.The root of the maxillary canines are the longest root of any tooth and conical in shape.Oral Anatomy, Histology and Embryology Barry K. B. Berkovitz, G. R. Holland, and Bernard J. Moxham Chapter 2.


Mandibular canine morphology

The lower canine teeth are placed nearer the middle line than the upper, so that their summits correspond to the intervals between the upper canines and the lateral incisors. From a facial aspect, the mandibular canine is notably narrower mesiodistally than the maxillary one, the root is compressed mesiodistally with well-marked grooves on both sides and may be just as long as the maxillary (and at times bifurcated). A distinctive feature is the nearly straight outline this tooth has compared to the maxillary canine which is slightly more bowed. As in the maxillary canine, the mesial incisal edge (or cusp ridge) is shorter than the distal side, however, the cusp is displaced slightly lingual relative to the cusp of the maxillary canine. Lingually, the surface of the tooth is much smoother compared to the very pronounced surface of the maxillary canine, and the cingulum is noted as less developed. The cusp may be lost with attrition over time and may resemble an upper second permanent incisor.


Sexual dimorphism

With many species, the canine teeth in the upper or lower jaw, or in both, are much larger in the males than in the females, or are absent in females, except sometimes a hidden rudiment. Certain antelopes, the musk-deer,
camel A camel is an even-toed ungulate in the genus ''Camelus'' that bears distinctive fatty deposits known as "humps" on its back. Camels have long been domesticated and, as livestock, they provide food (milk Milk is a nutrient-rich liquid ...
,
horse The horse (''Equus ferus caballus'') is a domesticated odd-toed ungulate mammal. It belongs to the taxonomic family Equidae and is one of two Extant taxon, extant subspecies of wild horse, ''Equus ferus''. The horse has evolution of the horse, ...

horse
,
boar The wild boar (''Sus scrofa''), also known as the "wild swine", "common wild pig", or simply "wild pig", is a suid native to much of Eurasia Eurasia () is the largest continental area on Earth, comprising all of Europe and Asia. Primar ...

boar
, various apes, seals, and the
walrus The walrus (''Odobenus rosmarus'') is a large flippered marine mammal with a discontinuous distribution about the North Pole in the Arctic Ocean and subarctic seas of the Northern Hemisphere. The walrus is the only living species in the fami ...

walrus
, offer instances.The Descent of Man. Charles Darwin. s:Descent of Man/Chapter XVII


In non-mammals

In non-mammals, teeth similar to canines may be termed "caniniform" ("canine-shaped") teeth.


Additional images

File:3D Medical Animation Still Showing Types of Teeth.jpg, Medical animation showing Canine teeth and their arrangement in the mouth of an adult human being. File:Illu mouth.jpg, Mouth (oral cavity) File:Gray157.png, Left maxilla. Outer surface. File:Gray187.png, Base of skull. Inferior surface. File:Gray1001.png, Unerupted permanent teeth underlie the deciduous teeth.


See also

* Carnassial * Incisor * Premolar * molar (tooth), Molar


References


External links

* {{Authority control Teeth Mammal anatomy Types of teeth