Paul Finkel, age 15, of Westlake Village, Calif., for his question:

WHY ARE WISDOM TEETH CALLED THAT?

The 12 teeth farthest back in the mouth are molars, with three on each side of the upper and lower jaws. The third molars are sometimes called wisdom teeth because they usually appear during late adolescence or early adulthood, supposedly at a time when a person is acquiring the most wisdom during his lifetime.

Four wisdom teeth start to develop in most people between the ages of 17 and 21. Many people, however, never develop them at all.

Incisors, cuspids and bicuspids have only one root, while the molars have two or three. And because they are the last to develop, oftenthe third molars have twisted roots that make extraction difficult. The four wisdom teeth aren't necessary tools in most mouths.