Simple answer to "what are wisdom teeth good for?" is pretty much, "absolutely nothing."
Humans get a set of molars at around age six, named by Dr. Obvious to be the six year (or first) molars. Another set of molars come in at age 12 named, you guessed it, the 12 year (or second) molars. The wisdom teeth are the common name for the 18 year (or third) molars. This corresponds to the time in life when you really know everything there is to know, hence the "wisdom" part of the name.
For most people, the wisdom teeth need to be removed. Generally, people do not have sufficient space to accommodate the wisdom teeth. When cramped for space, wisdom teeth tend to come in at a 45 (or worse) degree angle and lean on the 12 year molar. This can cause all kinds of problems for the 12 year molar, ranging from decay to actual resorption, where the tooth will just start eroding away due to the pressure. This fight for space between the molars also can cause headaches, shifting in tooth position, jaw pain and TMJ discomfort.
Removing the wisdom teeth is especially important for those who have had orthodontic treatment. Braces are recommended when the teeth are crowded, spaced improperly, rotated or the bite is incorrect. After the teeth are straightened and the bite is corrected, the wisdom teeth can erupt and destroy what has been corrected. There are studies that show that wisdom teeth do not have the force to disrupt the other teeth, but if you ask any dentist working on post-orthodontic patients, they will tell you otherwise.
Most people do not chew as far back as the wisdom teeth extend. The six year (or first) molar position takes on about 80% of the force of chewing. The 12 year (or second) molar and the premolars take up the rest of the force. So if the potential for causing problems is great and the tooth serves no real purpose, why keep it? Dentists are in the business of saving teeth, but if the risks outweigh the benefits, the choice becomes real clear.
Wisdom teeth are dirt collectors, too. People have a hard time brushing them, and people who actually floss their wisdom teeth are about as rare as snowplows in Florida. With neglect, wisdom teeth get decay. Decay can be extensive, sometimes requiring a root canal and crown in order to restore the tooth. In this writer's opinion, little is gained by sinking thousands of dollars into a non-functioning tooth. Having said that, occasionally (such as when the wisdom tooth is functional) the recommendation to restore wisdom teeth is the valid and prudent option.
Removing the wisdom teeth is best done in the later teen years. As time goes on, the extraction of wisdom teeth becomes more difficult and healing can be slower. Most people should schedule these extractions right after senior year of high school (sooner though, if there are problems). High school activities and sports are out of the way and college has not started yet, so the summer after senior year tends to be the best time.
The dentist will probably recommend a panoramic x-ray to determine how many wisdom teeth are present, their position, and whether a referral to an oral surgeon is needed. Teens undergoing wisdom tooth extractions should expect to be laying low for a couple of days, probably eating ice cream and pain meds, but will bounce back to their regular activities fast. And do not worry - they will still have all the "wisdom" they had before!
