Humans have two sets of dentitions during their lifetime. The first set appearing is the primary dentition with a total number of 20 teeth. Teeth of the primary dentition are also known as deciduous, baby, or milk teeth. 

During childhood, these teeth slowly get replaced by the teeth of the secondary dentition, which is also referred to as the permanent teeth. Adults have 32 permanent teeth.

The permanent teeth that replace deciduous teeth are called succedaneous teeth, but some teeth do not have correspondent teeth from the primary dentition. Therefore, the permanent teeth are divided into two subdivisions:

• The first one is teeth that replace the primary teeth. This subdivision includes the incisors, canines and premolars (premolar teeth).
• The second subdivision contains teeth without ancestors, which are the molars (molar teeth) of the secondary dentition (Note that the oral cavity has three molars on each side of the upper and lower jaw, but the 3D model lacks the third ones!).

Note: The molar teeth in children (primary molars) correspond to the premolar teeth in adults (secondary premolars).