Humans have two sets of dentitions during their lifetime, and the deciduous teeth are the first dentition that appears. Children have 20 deciduous teeth. These teeth are also known as the primary, baby or milk teeth, and the set of deciduous teeth is referred to as the primary dentition. 

Deciduous teeth are essential as later they get replaced by permanent teeth. Therefore, the primary teeth help to maintain space for the secondary dentition. A lack of a deciduous tooth can cause crooked permanent teeth.

Primary teeth are smaller with smaller roots, but they have relatively larger and bigger pulp chambers compared to the teeth of the secondary dentition, but it is not the only difference.

Other differences include the following:

• Deciduous teeth tend to be whiter than permanent teeth.
• The crown part of the deciduous teeth is shorter and broader.
• The milk teeth have no mamelons.
• The baby teeth have more prominent cervical ridges and a thinner enamel layer.
• The roots of the deciduous teeth are thinner and more widespread, with short or absent root trunks.

Overall, the deciduous teeth are very variable in shape and size.

Note: The Universal Tooth Numbering System for primary dentition is used for teeth numbering in this article. Find out what it is and which are the two other most commonly used teeth numbering systems in the article about the dental notation systems!