28. erythematous gingivae around the crown of a wisdom tooth

An 18-year-old woman presented with severe pain from her lower right molar area for 5 days. Extra-oral examination showed her to be afebrile with a mild, tender, erythematous swelling of her face at the right angle of the mandible associated with trismus and ipsilateral regional lymphadenopathy. Intra-orally, a diffuse swelling of the gingivae above her right mandibular third molar was found, centrally ulcerated and covered with whitish pseudo-membrane (Figure 1) with haemorrhagic pus exuding on palpation. No other lesions were seen in her mouth. She had good oral hygiene with no serious medical problems but smoked a packet of cigarettes daily and drank alcohol occasionally.

Pericoronitis is the most likely cause of the gingival inflammation here. This inflammation is caused by bacteria and food debris beneath the operculum of the partially erupted wisdom tooth. The short duration of symptoms and the presence of pus exudate indicate acute infection. Acute inflammation of the gingivae is also seen in acute ulcerative necrotizing gingivitis, a condition commonly seen among young patients who are chronic smokers with poor oral hygiene and some degree of immunodeficiency. This is a gingival infection from anaerobic bacteria causing necrosis of the interdental papillae of all or almost all teeth and is not usually restricted to the operculum, as seen in this patient. Trauma of the gingivae around the partially erupted third molar happens often during mastication but its symptomatology is milder, although it may contribute to pericoronitis. Syphilis, an infection with Treponema pallidum, can involve any area in the mouth including the retromolar area, but is rather asymptomatic and does not cause trismus. Oral carcinoma is more commonly seen in the retromolar areas of heavy drinkers or smokers of middle age rather than young patients.