Your teeth

You bite into an apple and then try to start talking to your friend about yesterday's math homework. Suddenly something feels funny — one of your baby teeth has fallen out! It's been loose forever, and now there it is, right in your hand. And you have an empty space in your mouth big enough to poke a drinking straw through.

Before you put that tooth under your pillow, did you know that there is much more to that tooth than meets the eye? A single tooth has many different parts that make it work. And teeth play an important role in your daily life. They not only let you eat stuff like apples, they also help you talk. So let's talk teeth!
Tiny Teeth

Unlike your heart or brain, your teeth weren't ready to work from the day you were born. Although babies have the beginnings of their first teeth even before they are born, teeth don't become visible until babies are about 6 to 12 months old.

After that first tooth breaks through, more and more teeth begin to appear. Most kids have their first set of teeth by the time they are 3 years old. These are called the primary or baby teeth, and there are 20 in all. When a child gets to age 5 or 6, these teeth start falling out, one by one.

A primary tooth falls out because it is being pushed out of the way by the permanent tooth that is behind it. Slowly, the permanent teeth grow in and take the place of the primary teeth. By about age 12 or 13, most kids have lost all of their baby teeth and have a full set of permanent teeth.

There are 28 permanent teeth in all — eight more than the original set of baby teeth. Between the ages of 17 and 21, four more teeth called wisdom teeth usually grow in at the back of the mouth. They complete the adult set of 32 teeth.

Source: http://www.amazines.com/