Why Are They Called 'Wisdom Teeth,' and Do I Really Need Them? These teeth are third molars at the back of your mouth, in both the upper and lower jaws. They came to be called wisdom teeth because they often appear later than all the other teeth, usually between ages 17 and 25. People are supposed to be wiser the older they get, so they came to be called "wisdom teeth." Most adults have four wisdom teeth. Some have more, called "supernumerary" teeth. About 35% of the population doesn't have any.
The problem is that most people don't have room in their mouths for these "extra" teeth. They can fail to erupt through the gums, which is called impaction. There are four kinds of impaction:
Mesioangular, when the tooth grows toward the front of the mouth
Vertical, when the tooth simply fails to grow upward
Distoangular, when the tooth angles backward in the mouth
Horizontal, when the tooth grows sideways into the roots of the adjacent tooth
Wisdom teeth may also partially erupt, so that the tooth rises above the gumline but is covered by a flap of gum tissue. It's fairly rare that they come in straight and don't cause any trouble. These troubles often include:
Pushing and crowding of the other teeth, which can cause these teeth to twist and turn.
Increased risk of cavities in these teeth and especially the adjacent teeth. It's too cramped to get them really clean.
Infection in the jaw bone, which is fairly common due to the difficulty in keeping them clean.
