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Incisors (from Latin incidere, "to cut") are the first kind of tooth
Tooth

Teeth are small whitish structures found in the jaws of many vertebrates that are used to tear, scrape, and chew food. Some animals, particularly carnivores, also use teeth for hunting or defense....
 in heterodont
Heterodont

The anatomical term heterodont refers to animals which possess more than a single tooth morphology . For example, members of the Synapsida generally possess incisors, Canine_, premolars, and molars....
 mammal
Mammal

Mammals are a class of vertebrate animals whose name is derived from their distinctive feature, mammary glands, with which they feed their young....
s. They are located in the premaxilla
Premaxilla

The incisive bone is the portion of the maxilla adjacent to the incisors.The term premaxilla can also be used to refer to the incisive bone....
 above and mandible below.

any herbivorous or omnivorous mammals, such as the human
Human

A human being, also human or man, is a member of a species of bipedalism primates in the family Hominidae . Mitochondrial DNA evidence indicates that modern humans originated in east Africa about 200,000 years ago....
 and the horse
Horse

The horse is a hoofed mammal, a subspecies of one of seven extant species of the family Equidae. The horse has evolution of the horse over the past 45 to 55 million years from a small multi-toed creature into the large, odd-toed ungulate animal of today....
, they are adapted for shearing sharply. In cat
Cat

The cat , also known as the Domestication cat or house cat to distinguish it from other Felinae and Felidae, is a small predationy carnivore species of crepuscular mammal that is valued by humans for its companionship and its ability to hunt vermin, snakes, scorpions, and other unwanted household pests....
s, the incisors are small; biting off meat is done with the canines
Canine tooth

In mammalian oral anatomy, the canine teeth, also called cuspids, dogteeth, fangs, or eye teeth, are relatively long, pointed tooth....
 and the carnassial
Carnassial

Carnassials are large teeth found in many carnivorous mammals, used for shearing flesh and bone in a scissor or shear-like way. In the Carnivora, the carnassials are the modified last upper premolar and the first lower molar , but in the prehistoric creodonts, the carnassials were further back in the jaw — first upper and second lower o...
s. In elephant
Elephant

Elephants are large land mammals of the order Proboscidea and the family Elephantidae. There are three living species: the African Bush Elephant, the African Forest Elephant and the Asian Elephant ....
s, the upper incisors are modified into curved tusk
Tusk

Tusks are unusually long teeth, usually but not always in pairs, that protrude well beyond the mouth of certain mammal species. They are most commonly canine tooth, as with warthogs, boar , and walruses, or, in the case of elephants and narwhals, elongated incisors....
s, just as is the case with Narwhal
Narwhal

The narwhal is a medium-sized toothed whale that lives year-round in the Arctic. One of two species of whale in the Monodontidae family , along with the Beluga whale, the narwhal males are distinguished by a characteristic long, straight, helical tusk extending from their upper left jaw....
s, where normally one of them develops into a straight and twisted tusk.






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Incisors (from Latin incidere, "to cut") are the first kind of tooth
Tooth

Teeth are small whitish structures found in the jaws of many vertebrates that are used to tear, scrape, and chew food. Some animals, particularly carnivores, also use teeth for hunting or defense....
 in heterodont
Heterodont

The anatomical term heterodont refers to animals which possess more than a single tooth morphology . For example, members of the Synapsida generally possess incisors, Canine_, premolars, and molars....
 mammal
Mammal

Mammals are a class of vertebrate animals whose name is derived from their distinctive feature, mammary glands, with which they feed their young....
s. They are located in the premaxilla
Premaxilla

The incisive bone is the portion of the maxilla adjacent to the incisors.The term premaxilla can also be used to refer to the incisive bone....
 above and mandible below.

Function

In many herbivorous or omnivorous mammals, such as the human
Human

A human being, also human or man, is a member of a species of bipedalism primates in the family Hominidae . Mitochondrial DNA evidence indicates that modern humans originated in east Africa about 200,000 years ago....
 and the horse
Horse

The horse is a hoofed mammal, a subspecies of one of seven extant species of the family Equidae. The horse has evolution of the horse over the past 45 to 55 million years from a small multi-toed creature into the large, odd-toed ungulate animal of today....
, they are adapted for shearing sharply. In cat
Cat

The cat , also known as the Domestication cat or house cat to distinguish it from other Felinae and Felidae, is a small predationy carnivore species of crepuscular mammal that is valued by humans for its companionship and its ability to hunt vermin, snakes, scorpions, and other unwanted household pests....
s, the incisors are small; biting off meat is done with the canines
Canine tooth

In mammalian oral anatomy, the canine teeth, also called cuspids, dogteeth, fangs, or eye teeth, are relatively long, pointed tooth....
 and the carnassial
Carnassial

Carnassials are large teeth found in many carnivorous mammals, used for shearing flesh and bone in a scissor or shear-like way. In the Carnivora, the carnassials are the modified last upper premolar and the first lower molar , but in the prehistoric creodonts, the carnassials were further back in the jaw — first upper and second lower o...
s. In elephant
Elephant

Elephants are large land mammals of the order Proboscidea and the family Elephantidae. There are three living species: the African Bush Elephant, the African Forest Elephant and the Asian Elephant ....
s, the upper incisors are modified into curved tusk
Tusk

Tusks are unusually long teeth, usually but not always in pairs, that protrude well beyond the mouth of certain mammal species. They are most commonly canine tooth, as with warthogs, boar , and walruses, or, in the case of elephants and narwhals, elongated incisors....
s, just as is the case with Narwhal
Narwhal

The narwhal is a medium-sized toothed whale that lives year-round in the Arctic. One of two species of whale in the Monodontidae family , along with the Beluga whale, the narwhal males are distinguished by a characteristic long, straight, helical tusk extending from their upper left jaw....
s, where normally one of them develops into a straight and twisted tusk. The incisors of rodent
Rodent

Rodentia is an Order of mammals also known as rodents, characterised by two continuously growing Incisors#The_Rodent_incisor in the upper and lower jaws which must be kept short by gnawing....
s grow throughout life and are worn by gnawing.

Number and types of incisors


In humans

Human
Human

A human being, also human or man, is a member of a species of bipedalism primates in the family Hominidae . Mitochondrial DNA evidence indicates that modern humans originated in east Africa about 200,000 years ago....
s normally have eight (8) incisors, two of each type. The types of incisors are:
  • maxillary central incisor
    Maxillary central incisor

    The maxillary central incisor is a human tooth in the front upper jaw, or maxilla, and is usually the most visible of all teeth in the mouth. It is located Commonly used terms of relationship and comparison in dentistry to the maxillary lateral incisor....
  • maxillary lateral incisor
    Maxillary lateral incisor

    The maxillary lateral incisor is the tooth located distally from both maxillary central incisors of the mouth and mesially from both maxillary canines....
  • mandibular central incisor
    Mandibular central incisor

    The mandibular central incisor is the tooth located on the mandible, adjacent to the midline of the face. It is mesial from both mandibular lateral incisors....
  • mandibular lateral incisor
    Mandibular lateral incisor

    The mandibular lateral incisor is the tooth located distally from both mandibular central incisors of the mouth and mesially from both mandibular canine....


In Non-human animals

Among other animals, some other primate
Primate

A primate is a member of the biological order Primates , the group that contains lemurs, the Aye-aye, Lorisidaes, galagos, tarsiers, monkeys, and apes, with the last category including humans....
s, cats and horses have twelve. Rodent
Rodent

Rodentia is an Order of mammals also known as rodents, characterised by two continuously growing Incisors#The_Rodent_incisor in the upper and lower jaws which must be kept short by gnawing....
s have four. Rabbits and hares (lagomorphs) were once considered rodents, but are distinguished by having eight--1 small pair, called "peg teeth" is directly behind the most anterior pair.

Additional images


See also

  • canine tooth
    Canine tooth

    In mammalian oral anatomy, the canine teeth, also called cuspids, dogteeth, fangs, or eye teeth, are relatively long, pointed tooth....
  • premolar
    Premolar

    The premolar teeth or bicuspids are transitional teeth located between the Canine_tooth and Molar_ teeth. In humans, there are two premolars per quadrant, making eight premolars total in the mouth....
  • molar
    Molar (tooth)

    Molars are the rearmost and most complicated kind of tooth in most mammals. In many mammals they grind food; hence the Latin name mola, "millstone"....