What are the reasons people get their wisdom teeth pulled?

Impaction/pain: Wisdom teeth commonly affect other teeth as they develop, becoming impacted or "coming in sideways." they are often extracted when this occurs.

Don't fit: Often wisdom teeth don't have room to fit properly, they are positioned sideways, or develop a cyst around them. If any of these things happen they are often taken out in late teens to early 20s to prevent damage to the surrounding teeth. Sometimes partially erupted wisdom teeth get food and/or bacteria trapped under the surrounding gums that creates an infection that requires extraction.

Several: Indications for removal of wisdom teeth may include but are not limited to decay, periodontal problems, pathology associated with the wisdom tooth or adjacent structures, insufficient space for eruption, impacted or partially impacted positions with the potential for problems if not removed, and in conjunction with orthodontic therapy.