|by Marcia Malory|
A mammal's mouth contains teeth that have different shapes so that they can perform different functions.
Animals that have different kinds of specialized teeth are known as heterodonts.
Mammals are the only living heterodonts.
Mammals have four basic kinds of teeth - incisors, canines, premolars and molars.
In some mammals, certain kinds of teeth have been modified to better suit those mammals' lifestyles.
Incisors, which are located in the front of the mouth, are used for cutting and biting.
They normally have straight, sharp cutting edges.
In rodents, the incisors are modified to behave as chisels.
In elephants, the upper incisors have become tusks.
The incisors of vampire bats act like scalpels; they make small cuts from which blood can be drawn.
Canine teeth, which can be found next to the incisors, have sharp, pointed edges.
They can be used for stabbing and holding prey, for biting into food, and for fighting.
Canines are sometimes called fangs or eye teeth.
They are often the largest teeth in a mammal's mouth.
Mammals with very large canines, such as baboons, will sometimes show their canines as part of social displays.
In many mammals, the canines are larger in males than in females.
The canines of herbivorous (plant-eating) mammals are missing or very small.
The premolars can be found behind the canines.
They are used for crushing and grinding.
Premolars are broad with irregular lumps on top. These lumps are known as cusps. Because they usually have two cusps, premolars are sometimes known as bicuspids.
The molars, which are in the back of the mouth, are also used for crushing and grinding. They also have cusps on their upper surfaces.
In some carnivores, the last premolar in the upper jaw and the first molar in the bottom jaw are sharper and slimmer and can be used to cut flesh. These modified teeth are known as carnassials.
The other molars and premolars may be reduced in size or missing.
In human beings, the molars closest to the back of the mouth are known as wisdom teeth.
Most mammals have two sets of teeth in their lifetime.
The teeth in the first set are known as deciduous teeth, temporary teeth, milk teeth or baby teeth.
These teeth are smaller and weaker than permanent, or adult, teeth, and there are fewer temporary teeth than permanent teeth.
A set of deciduous teeth is made up of incisors, canines and molars. These molars differ from the molars that are found in a set of adult teeth.
An animal that grows two sets of teeth during its life is known as a diphyodont.