cheek that overlies the angle of the jaw. Persons typically develop pericoronitis in their late teens and early 20s, as this is the age that the wisdom teeth are erupting. Treatment for acute conditions includes cleaning the area under the operculum with an antiseptic solution, painkillers, and antibiotics if indicated. After the acute episode has been controlled, the definitive treatment is usually by tooth extraction or, less commonly, the soft tissue is removed (operculectomy). If the tooth is kept, good oral hygiene is required to keep the area free of debris to prevent recurrence of the infection. Occlusal trauma Occlusal trauma results from excessive biting forces exerted on teeth, which overloads the periodontal ligament, causing periodontal pain and a reversible increase in tooth mobility. Occlusal trauma may occur with bruxism, the parafunctional (abnormal) clenching and grinding of teeth during sleep or while awake. Over time, there may be attrition (tooth wear), which may also cause dentin hypersensitivity, and possibly formation of a periodontal abscess, as the occlusal trauma causes adaptive changes in the alveolar bone. Occlusal trauma often occurs when a newly placed dental restoration is built too "high", concentrating the biting forces on one tooth. Height differences measuring less than a millimeter can cause pain. Dentists, therefore, routinely check that any new restoration is in harmony with the bite and forces are distributed correctly over many teeth using articulating paper. If the high spot is quickly eliminated, the pain disappears and there is no permanent harm. Over-tightening of braces can cause periodontal pain and, occasionally, a periodontal abscess. Alveolar osteitis Alveolar osteitis is a complication of tooth extraction (especially lower wisdom teeth) in which the blood clot is not formed or is lost, leaving the socket where the tooth used to be empty, and bare bone is exposed to the mouth. The pain is moderate to severe, and dull, aching, and throbbing in character. The pain is localized to the socket, and may radiate. It normally starts two to four days after the extraction, and may last 10–40 days. Healing is delayed, and it is treated with local anesthetic dressings, which are typically required for five to seven days. There is some evidence that chlorhexidine mouthwash used prior to extractions prevents alveolar osteitis. Combined pulpal-periodontal Dental trauma and cracked tooth syndrome Cracked tooth syndrome refers to a highly variable set of pain-sensitivity symptoms that may accompany a tooth fracture,