There are several reasons why you may need to have your wisdom teeth removed, including:
Impacted wisdom tooth. This is when the tooth only partially emerges from your gums and it can lead to infection. Impacted teeth can also suffer from serious tooth decay, or can lead to the formation of cysts, which can destroy bone and damage nearby teeth.
Tooth decay. It can be very difficult to properly clean an impacted wisdom tooth, and bacteria, food and other nasties can accumulate in the area and cause decay.
Gum infection. If a wisdom tooth only partially emerges from the gum, this can cause food and bacteria to get stuck beneath the gum and cause infection.
Pressure pain. As wisdom teeth emerge, they put a great deal of pressure on other teeth in your mouth as they make room for the new arrival. This can cause extreme pain and also erode other teeth.
Orthodontic purposes. If you've previously received orthodontic treatment to straighten your teeth, the pressure caused by wisdom teeth can counteract that treatment and push your teeth out of place.
Dentures. It is typically recommended that most people who require dentures have their wisdom teeth removed.