Final answer:
Deciduous teeth, also known as baby teeth, appear at around 6 months and fall out between 20 and 30 months after birth, when they are replaced by permanent teeth.
Step-by-step explanation:
Deciduous teeth, also known as baby teeth, begin to appear at around 6 months of age in infants. A total of 20 deciduous teeth erupt between 6 months and 30 months after birth. After the deciduous teeth fall out, they are replaced by the permanent teeth, which usually emerge between the ages of 6 and 12.