ANSWER:

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.[2] 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:

Human: deciduous teeth: 212/212; adult = 2123/2123. Both childhood molars are replaced by adult premolars. Adult total is double the formula = 32.