Dental Abscess

Dental abscess is the broader entity of a purulent odontogenic infection, whether from the tooth apex (periapical), the periodontal pocket (periodontal) or the pericoronal tissue, and the stages by which it extends beyond the alveolar bone into soft tissue spaces of the head and neck. This article addresses clinical staging, spread to fascial spaces, systemic complications, and drainage and antibiotic management.

Infection progresses from inoculation (cellulitis, days 1 to 3) to abscess formation (days 4 to 7). The route of spread follows the thickness of the bone and attachment of muscles: maxillary teeth drain through buccal bone to the vestibule or into the palate, canine fossa and infraorbital space; mandibular molars drain to the sublingual, submandibular or masticator spaces, as the mylohyoid and buccinator attachments determine.

Deep fascial spaces involved include the submandibular, sublingual (Ludwig angina when bilateral submandibular, sublingual and submental spaces are involved), parapharyngeal, retropharyngeal, masticator, buccal and temporal spaces. Complications are airway obstruction, mediastinitis, cavernous sinus thrombosis, brain abscess, osteomyelitis, orbital cellulitis, sepsis, and Lemierre syndrome. Mortality of deep neck infections is 1 to 5 percent but higher with delays.

• Localised abscess: throbbing pain, fluctuant intraoral swelling, tooth tender to percussion.
• Cellulitis: diffuse firm facial swelling, erythema, warmth, with obliteration of landmarks.
• Fascial space infection: trismus (mouth opening under 30 mm), dysphagia, odynophagia, drooling, muffled voice, neck swelling, torticollis, fever, tachycardia, malaise, dehydration.
• Ludwig angina: bilateral woody floor of mouth swelling, elevated tongue, stridor.
• Orbital extension: periorbital oedema, proptosis, ophthalmoplegia, visual loss.
• Red flags: airway compromise, inability to swallow saliva, stridor, trismus, sepsis (hypotension, tachycardia, altered consciousness), diabetes, HIV.

• Clinical assessment of airway, vital signs, mouth opening, swelling extent, tooth source, floor of mouth, and neck.
• Blood tests: white cell count, C-reactive protein, glucose, renal function, lactate for sepsis; blood cultures before antibiotics when febrile; HIV test.
• Contrast CT of the head and neck for suspected deep neck space infection, airway compromise, trismus, or lack of response in 48 hours: rim enhancing collection, gas, fat stranding, airway narrowing, mediastinal extension.
• Panoramic radiograph or periapical film for dental source; ultrasound for superficial collections.
• Pus culture and sensitivity at drainage.
• Exclude cellulitis from other cause, salivary gland infection, lymphadenitis, tonsillar abscess, angioedema, mumps, osteomyelitis, and tumour.

• Airway is first priority: assess, with senior anaesthetic help for Ludwig angina, stridor, trismus or drooling; awake fibre optic nasal intubation or a tracheostomy under local anaesthesia; avoid supine positioning and sedation.
• Surgical drainage is the definitive treatment: intraoral incision for localised abscess; extraoral incision (submandibular, 2 cm below the mandible) with blunt dissection and drain placement for deep space infections; remove the offending tooth when possible during the same procedure.
• Antibiotics for spreading infection or systemic features: benzylpenicillin 1.2 to 2.4 g intravenously every 6 hours with metronidazole 500 mg intravenously every 8 hours, reviewing at 48 hours; change to oral amoxicillin 500 mg every 8 hours with metronidazole 400 mg every 8 hours to complete 5 to 7 days after drainage. Penicillin allergy: clindamycin 600 mg intravenously every 8 hours. Children: benzylpenicillin 50 mg/kg every 6 hours and metronidazole 7.5 mg/kg every 8 hours. For septic shock: ceftriaxone 2 g intravenously once daily with metronidazole 500 mg every 8 hours.
• Analgesia: paracetamol 1 g intravenously or orally every 6 hours, ibuprofen 400 mg every 8 hours, opioid for severe pain.
• Dexamethasone 8 mg intravenously once may reduce airway oedema in impending airway compromise, balanced against uncontrolled infection.
• Fluid resuscitation with crystalloid, glycaemic control (target 6 to 10 mmol/L), nutritional support, and chlorhexidine 0.2 percent mouthwash 10 mL twice daily.
• Admission criteria: trismus, systemic features, swelling reaching the floor of mouth or neck, immunosuppression, or failed outpatient treatment.
• Mediastinitis and orbital extension need combined surgical teams, broad antibiotics (meropenem 1 g intravenously every 8 hours), and ICU care.
• Follow up: dental treatment of the source (root canal treatment or extraction), with review at 1 week; recurrence indicates retained root, foreign body, or osteomyelitis.
• Prevention: caries control, early treatment of toothache, and avoidance of untreated infections in diabetes.