Pericoronitis is a swelling or inflammation of the gum tissue. It commonly occurs around your wisdom teeth, the third and final set of molars most people obtain in their late teens or early twenties. It is more frequent in your lower teeth. The crown of the erupting tooth is typically partially covered by a flap of the gum tissue in patients with pericoronitis. Depending on several variables, your doctor can advise removing the flap or extracting the pericoronitis wisdom tooth. Sometimes the best way is to treat the actual symptoms merely.