Dentition
[1] That is, the number, type, and morpho-physiology (that is, the relationship between the shape and form of the tooth in question and its inferred function) of the teeth of an animal.
The dentition of animals in which the teeth are continuously discarded and replaced throughout life is termed polyphyodont.
Current theories suggest either an "outside-in" or "inside-out" evolutionary origin to teeth, with the dentition arising from odontodes on the skin surface moving into the mouth, or vice versa.
[3] Despite this debate, it is accepted that vertebrate teeth are homologous to the dermal denticles found on the skin of basal Gnathostomes (i.e.
The teeth in the upper and lower jaws in mammals have evolved a close-fitting relationship such that they operate together as a unit.
Their function is cutting, slicing, or gnawing food into manageable pieces that fit into the mouth for further chewing.
If the interdigitation of the opposing cusps and incisal edges are not directed properly the teeth will wear abnormally (attrition), break away irregular crystalline enamel structures from the surface (abrasion), or fracture larger pieces (abfraction).
The incisors mostly control the vertical opening of the chewing cycle when the muscles of mastication move the jaw forwards and backwards (protrusion/retrusion).
The outer extremities of this envelope are limited by muscles, ligaments and the articular disc of the TMJ.
Without the guidance of anterior incisors and canines, this envelope of function can be destructive to the remaining teeth resulting in periodontal trauma from occlusion seen as wear, fracture or tooth loosening and loss.
Depending on the particular mammal and its diet, these two kinds of teeth prepare pieces of food to be swallowed by grinding, shearing, or crushing.
Tooth form has also undergone evolutionary modification as a result of natural selection for specialised feeding or other adaptations.
Over time, different mammal groups have evolved distinct dental features, both in the number and type of teeth and in the shape and size of the chewing surface.
This is because the terms of human dentistry, which have generally prevailed over time, have not included mammalian dental evolutionary theory.
A dinosaur's dentition included all the teeth in its jawbones, which consist of the dentary, maxillary, and in some cases the premaxillary bones.
The predentary is a smaller bone that forms the anterior end of the lower jaw in ornithischian dinosaurs; it is always edentulous and supported a horny beak.
Unlike modern lizards, dinosaur teeth grew individually in the sockets of the jawbones, which are known as the dental alveoli.
Occlusion refers to the closing of the dinosaur's mouth, where the teeth from the upper and lower parts of the jaw meet.
Dinosaur tooth shapes included cylindrical, peg-like, teardrop-shaped, leaf-like, diamond-shaped and blade-like.
The teeth of carnivorous dinosaurs, called ziphodont, were typically blade-like or cone-shaped, curved, with serrated edges.
