Why do dentists recommend wisdom teeth removal?

Does my teenager really need to have their wisdom teeth removed? What if I still have my wisdom teeth as an adult?

First, a little history:

Wisdom teeth are the third molars. Normally people have three permanent molars that develop in each quadrant of the mouth; upper, lower, right and left. The first molars usually grow into the mouth at around six years of age. The second molars grow in at around age 12. The third molars usually will try to grow in at around age 17 to 21 years. Since that is considered to be the age when people become wiser, third molars gained the nickname, “wisdom teeth.” Actually, they are no different than any other tooth except that they are the last teeth to erupt, or grow into the mouth. They are just as useful as any other tooth if they have enough room to grow in properly, have a proper bite relationship and have healthy gum tissue around them. Unfortunately, this does not always happen.