Pericoronitis

Pericoronitis is inflammation of the soft tissue (operculum) surrounding the crown of a partially erupted tooth, most often the mandibular third molar, with subsequent infection by plaque bacteria trapped under the gingival flap. It affects young adults aged 17 to 25 years and is the main indication for third molar extraction. About 5 percent of those with impacted third molars develop acute pericoronitis each year.

Food debris and plaque collect in the pocket beneath the operculum, where anaerobic organisms (Fusobacterium, Prevotella, Streptococcus anginosus group) proliferate. The opposing upper molar can traumatise the flap and worsen the inflammation. Acute pericoronitis can spread to the cheek, submandibular, masticator and parapharyngeal spaces, causing trismus and deep neck infection. Recurrent chronic episodes occur until the tooth is extracted or erupts fully. Risk factors include poor hygiene, stress, upper respiratory infection and pregnancy.

• Mild: pain, swelling, redness of the operculum, bad taste, halitosis.
• Moderate: severe pain radiating to the ear, throat, and floor of mouth, painful swallowing, trismus, swollen cheek, and cervical lymphadenopathy, pus from beneath the flap, opposing tooth bite marks on the operculum.
• Severe: fever, malaise, facial swelling, difficulty opening the mouth (under 20 mm), deep space infection.
• Chronic: dull ache, recurrent episodes of bad taste.
• Red flags: dysphagia, floor of mouth swelling, airway narrowing, fever over 38.5 degrees C, and immunosuppression.

• Clinical diagnosis: partial eruption of third molar, erythematous and tender operculum, pus on pressure, sometimes trismus and lymphadenopathy.
• Measure mouth opening and temperature; examine the oropharynx and neck.
• Panoramic radiograph or periapical view: angulation and depth of impaction, relationship to the inferior alveolar canal, caries on the adjacent second molar, pericoronal radiolucency.
• Cone beam CT before surgery when the third molar is close to the inferior alveolar canal.
• Blood tests (white cell count, C-reactive protein) when systemic features occur.
• Exclude periapical abscess, dental caries of the second molar, odontogenic cyst, tonsillitis, temporomandibular disorder, and malignancy (rare).

• Local measures are first line: irrigate under the operculum with warm normal saline or chlorhexidine gluconate 0.2 percent using a blunt syringe (10 to 20 mL), debride debris, and use topical anaesthetic gel (lidocaine 5 percent) before irrigation. Occlusal adjustment by grinding or extracting the opposing upper third molar if it traumatises the operculum.
• Patient rinses: chlorhexidine 0.2 percent mouthwash 10 mL for 1 minute twice daily for 7 days; warm salt water rinses (half a teaspoon in a cup of warm water) every 2 hours.
• Analgesia: ibuprofen 400 mg orally every 8 hours with food and paracetamol 1 g every 6 hours (children: ibuprofen 5 to 10 mg/kg every 8 hours, paracetamol 15 mg/kg every 6 hours).
• Antibiotics are reserved for systemic involvement, fever, spreading infection or trismus: metronidazole 400 mg orally every 8 hours for 3 to 5 days (alone is usually sufficient), or amoxicillin 500 mg orally every 8 hours for 5 days; clindamycin 300 mg four times daily for 5 days if penicillin allergic; hospital admission with intravenous benzylpenicillin 1.2 g every 6 hours plus metronidazole 500 mg every 8 hours for deep space spread.
• Incise and drain a pericoronal abscess under local anaesthesia (lidocaine 2 percent with adrenaline 1:80 000).
• Definitive: extraction of the third molar (preferred after recurrent episodes) once acute infection settles (usually at 1 to 2 weeks); operculectomy by excising the flap only when the tooth is expected to erupt fully and is in good position (higher recurrence).
• Extraction complications: dry socket (1 to 4 percent), inferior alveolar nerve injury (0.5 to 5 percent, temporary; permanent under 1 percent), lingual nerve injury, bleeding, and infection.
• Follow up: review at 48 hours and 1 week; after extraction review at 1 week.
• Prevention: oral hygiene around partially erupted teeth, early extraction of poorly positioned third molars, and regular dental review.