Editor-In-Chief: C. Michael Gibson, M.S., M.D. 
Pericoronitis is a common problem in young adults with partial tooth impactions. It occurs when the tissue around the wisdom tooth has become infected because bacteria have invaded the area. Food impaction and caries (tooth cavity) are also problems associated with third molar pain.
Treatment for minor symptoms of pericoronitis (spontaneous pain, localized swelling, purulence/drainage, foul taste) is irrigation. Major symptoms of pericoronitis (difficulty swallowing, enlarged lymph nodes, fever, limited mouth opening, facial cellulitis/infection) are usually treated with antibiotics. In most instances the symptoms will recur and the only definitive treatment is extraction. If left untreated, however, recurring infections are likely, and the infection can eventually spread to other areas of the mouth. The most severe cases are treated in a hospital and may require intravenous antibiotics and surgery.
The removal of the wisdom tooth (extraction) should occur at a time when the "infection" is not present, as extracting this tooth during the time of the acute/painful infection can cause the infection to spread to dangerous area around the throat. Therefore, a dentist will usually clean the area +/- prescribe antibiotics and wait for it to calm down until scheduling the extraction.