Tooth

related topics
{specie, animal, plant}
{disease, patient, cell}
{@card@, make, design}
{acid, form, water}
{island, water, area}
{work, book, publish}
{food, make, wine}
{mi², represent, 1st}
{math, number, function}
{line, north, south}
{area, part, region}
{school, student, university}

Teeth (singular tooth) are small, calcified, whitish structures found in the jaws (or mouths) of many vertebrates that are used to break down food. Some animals, particularly carnivores, also use teeth for hunting or for defensive purposes. The roots of teeth are covered by gums. Teeth are not made of bone, but rather of multiple tissues of varying density and hardness.

Teeth are among the most distinctive (and long-lasting) features of mammal species. Paleontologists use teeth to identify fossil species and determine their relationships. The shape of the animal's teeth are related to its diet. For example, plant matter is hard to digest, so herbivores have many molars for chewing and grinding. Carnivores, on the other hand, need canines to kill prey and to tear meat.

Mammals are diphyodont, meaning that they develop two sets of teeth. In humans, the first set (the "baby," "milk," "primary" or "deciduous" set) normally starts to appear at about six months of age, although some babies are born with one or more visible teeth, known as neonatal teeth. Normal tooth eruption at about six months is known as teething and can be painful.

Some animals develop only one set of teeth (monophyodont) while others develop many sets (polyphyodont). Sharks, for example, grow a new set of teeth every two weeks to replace worn teeth. Rodent incisors grow and wear away continually through gnawing, which helps maintain relatively constant length. The industry of the beaver is due in part to this qualification. Many rodents such as voles (but not mice) and guinea pigs, as well as rabbits, have continuously growing molars in addition to incisors.[1][2]

Contents

Full article ▸

related documents
Ferret
Shark
Brown Rat
Mollusca
Turtle
Butterfly
Cougar
Seahorse
Snake
Archaeopteryx
Orchidaceae
Bongo (antelope)
Plant breeding
Grizzly Bear
Neanderthal
Fossil
Great white shark
Biodiversity
Dominance (genetics)
Pterosaur
Eucalyptus
Hybrid (biology)
Species
Pearl
Domestication of the horse
Tiger
Ornithology
Paleontology
Invasive species
Deer