A baby is usually born with no visible teeth in their mouth. However, in a newborn baby, there are 20 fully formed milk teeth or primary teeth lying underneath the gums. These teeth loosen and fall out between the ages of 6 to 10 years to give way to adult teeth.
The term deciduous teeth refers to baby teeth, primary teeth, and milk teeth that are their first teeth. A few months after birth, they begin to arise through the gums after developing in the embryo stage. Typically, they live until the age of 21.