There is an interrelation between the form of teeth arid nature of food. These may be omnivorous, carnivorous, insectivorous herbivorous and rodents or gnawing. In Mammals dentition is complete in the first three types. Often incomplete in herbivores where the canines are absent. The absence of canines forms a gap between incisors and premolar. This is called diastema Rabbit). The canines are small or absent and the cheek teeth have broad grinding surfaces with transverse ridges - lophodont molars. In omnivorous mammals the incisors are suited for cutting the canines for tearing and cheek teeth with prominent crowns raised into rounded tubercles are adapted for crushing bunodont molars. In the carnivorous mammals, the incisors are either poorly developed or reduced and few in number and the canines are long and sharp suited for tearing and piercing the flesh But the molars with knife-like edges are modified for scratching the flesh from the bones. In the insectivores, the incisors of the upper and lower jaws become closely united to secure small active prey and the molars have sharp pointed crowns.
Depending upon the shape, size and number of cusps, the teeth are differentiated into:
- Monocuspici teeth - Teeth with one cusp or tubercie
- Bicuspid teeth - Teeth with two cusps.
- Tricuspid teeth - Teeth with three cusps and all the cusps are arranged in one plane by forming a triangle.
- Bunodont teeth - Teeth with a number of distinct blunt pointed cusps - Man and Monkey.
- Lophodont teeth - The cusps are fused in the form of ridges- Horse & Elephant.
- Selenodont teeth - Here the cusps are wear away, exposing the under lying dentineythich-getnuii by crescent -Shaped bands raf -
- Secodont teeth - The cusps are having sharp cuffing surfaces - carnivorous mammals. Carnassial teeth are present.
- Hypsodont teeth - The teeth are having long crown and deeply placed neck. - Horse
- Brachyodont teeth - Teeth with short crow, and neck at the surface gum. - Dog.
In sirenia (sea - Cow and Manatee), the teeth are devoid of enamel.