Dentition

Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, it is the characteristic arrangement, kind, and number of teeth in a given species at a given age. That is, the number, type, and morpho-physiology (the physical shape) of the teeth of an animal.

Animals whose teeth are all of the same type, such as most non-mammalian vertebrates, are said to have homodont dentition, whereas those whose teeth differ morphologically are said to have heterodont dentition. The dentition of animals with two successions of teeth (deciduous, permanent) is referred to as diphyodont, while the dentition of animals with only one set of teeth throughout life is monophyodont. The dentition of animals in which the teeth are continuously discarded and replaced throughout life is termed polyphyodont.

Overview

Vertebrate dentition originated from a folding in of the placoderm's armor, evolving into the familiar condition of living reptiles, amphibians, and fish: a long row of pointed or sharp-sided, undifferentiated teeth (homodont) that are completely replaceable. The mammalian pattern is significantly different. The teeth in the upper and lower jaws in mammals have evolved a close-fitting relationship such that they operate together as a unit. "They occlude, that is, the chewing surfaces of the teeth are so constructed that the upper and lower teeth are able to fit precisely together, cutting, crushing, grinding or shearing the food caught between."