Pericoronitis can develop when wisdom teeth only partially erupt (break through the gum). This allows an opening for bacteria to enter around the tooth and cause an infection. In cases of pericoronitis, food or plaque (a bacterial film that remains on teeth after eating) may get caught underneath a flap of gum around the tooth. If it remains there, it can irritate the gum and lead to pericoronitis. If the pericoronitis is severe, the swelling and infection may extend beyond the jaw to the cheeks and neck.

Symptoms of pericoronitis can include:

• Pain
• Infection
• Swelling in the gum tissue (caused by an accumulation of fluid)
• A "bad taste" in the mouth (caused by pus leaking from the gums)
• Swelling of the lymph nodes in the neck
• Difficulty opening the mouth