Deciduous teeth important for the development of the child's speech, for the child's smile and play a role in chewing of food, although children who have had their primary teeth removed (usually as a result of Dental caries) can still eat and chew to a certain extent. In almost all European languages the primary teeth are called "baby teeth" or "milk teeth". In the United States and Canada, the term "baby teeth" is common. In some Asian countries they are referred to as "fall teeth" since they will eventually fall out. Various cultures have customs relating to the loss of deciduous teeth.
Dentition 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: for example: di:dc:dp. 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, which can be written as , or I.C.P.M / I.C.P.M. For example, the following formulae show the deciduous and usual permanent dentition of all catarrhine primates, including humans: The greatest number of teeth in