Dental formula

A dental formula is a summary of a mammal's teeth.
Almost all mammals have four kinds of teeth:
Teeth numbers and form have adapted to different feeding methods. Over time, different mammal groups have evolved distinct dental features, in the number and type of teeth, and in the shape and size of the chewing surface.
The number of teeth of each type is written as a dental formula for one side of the mouth, or quadrant, with the upper and lower teeth shown on separate rows. The number of teeth in a mouth is twice that listed as there are two sides.
In each set, incisors (I) are indicated first, canines (C) second, premolars (P) third, and finally molars (M), giving I:C:P:M. So for example, the formula 2.1.2.3 for upper teeth indicates 2 incisors, 1 canine, 2 premolars, and 3 molars on one side of the upper mouth.
The deciduous dental formula is notated in lowercase lettering preceded by the letter d: e.g. di:dc:dm. An animal's dentition for either deciduous or permanent teeth can thus be expressed as a dental formula, written in the form of a fraction: I.C.P.M / I.C.P.M.
Since the teeth are always listed in the same order, the letters can be dropped, thus:
Both felines and horses have a large diastema, or gap, between their front teeth and their back teeth. This is a natural feature in many types of mammal.
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