This information letter from the Tooth Fairy tells a child why humans lose teeth and grow new ones.
Text of the letter:
I hear that you’re interested in learning more about why kids lose their teeth. I’d be happy to fill you in! People are born with two sets of teeth: baby teeth and adult teeth. All teeth have roots that keep the tooth in place in the gums. Baby teeth have shorter, weaker roots because they’re meant to be temporary until our bodies get bigger and are ready for the permanent teeth.
Our bodies also create special cells that help break down the baby teeth over time, making them weak and ready to wiggle and fall out. Most people lose their first baby tooth by age six or seven and their last one by thirteen or fourteen. Then the permanent teeth grow into the gaps. Those are bigger, a little yellower, and will last you the rest of your life if you take care of them by brushing and flossing every day.
The Tooth Fairy