The deciduous teeth or primary, milk, baby and temporary teeth are twenty in number,10 in each jaw ( 4 incisors, 2 canines and 4 molars).
They start to erupt at the age of six month by the appearance of the first deciduous mandibular incisors
in the oral cavity. At about 2 years old, the last deciduous tooth which is the second molar, starts to appears. At three year of age all the deciduos teeth are erupt and are in function.
As the term “deciduous” implies, teeth are shed in
order to make way for their permanent successors. The process of exfoliation takes place between the sixth and twelfth years. One to two years after complete root formation resorption begins at the root apex of the deciduous teeth and continues cervical until
resorption of the entire root has taken place and the crown is lost from lack of support.
The anterior deciduous teeth are replaced by the anterior permanent teeth, while the deciduous molars are replaced by the permanent premolars.
span of all the deciduous teeth in the oral cavity are from 6 months to 12 years of age, therefore, from 6 months to 6 years the oral cavity contains only deciduous teeth.
From 6-12 years, the oral cavity contains mixed dentition (deciduous and permanent).
From 12 years on, the oral cavity contains only permanent teeth.