Final answer:
The first set of primary teeth in infants and early childhood are known as deciduous teeth, which are later replaced by permanent teeth during middle childhood.
Step-by-step explanation:
The first set of primary teeth is also referred to as deciduous teeth. Deciduous teeth are the first set of 20 teeth that emerge in infants and early childhood. These teeth are lost and replaced by permanent teeth during middle childhood. They are often called baby teeth or milk teeth. It is in middle childhood that deciduous teeth loosen and fall out to make way for the emergence of most of the permanent teeth. The eight incisors are usually the first deciduous teeth to fall out, typically between the ages of six and eight.