What is the first set of teeth that grow during infancy and fall off between the age of six to eight called? 

Milk teeth, also known as baby teeth or deciduous teeth, are the first set of teeth that develop during childhood and fall out between the ages of six and eight years.

These teeth are temporary and are eventually replaced by permanent teeth, which usually start to emerge around the age of six and continue to develop until the late teens or early twenties.

The milk teeth are important for maintaining proper nutrition and speech development, and they also help guide the permanent teeth into their correct position.