Facial swelling and odontogenic infection — formative SAQs

SAQ 1 (10 marks)

A 6-year-old boy presents with three days of right-sided facial swelling and toothache. He has a fever of 38.6 degrees Celsius and has refused solid food today. On examination there is a firm, warm, tender swelling of the right cheek, tender right cervical lymphadenopathy, and a badly carious right lower molar that is tender to percussion. He has no trismus, drooling or airway compromise. [1] [4]

1. What is the most likely diagnosis and source, and what anatomical principle explains the cheek swelling? (3) [4]
2. Outline your management plan, including the role of source control and antibiotic choice with doses. (4) [1] [5]
3. Describe your safety-net advice and the features that would require immediate reassessment. (3) [2]

Model answer — SAQ 1

(1) Diagnosis and anatomy (3). The most likely diagnosis is a spreading odontogenic cellulitis arising from the carious right lower molar, with the periapical abscess having perforated the cortical bone into the buccal space. The anatomical principle is that the buccinator muscle attachment on the mandible determines the direction of spread: pus from a root apex that tracks buccally passes into the buccal space and presents as cheek swelling, whereas an apex below the mylohyoid line tracks into the submandibular space. Here the cheek swelling localises the collection to the buccal space. [4] [1]

(2) Management plan (4). The curative step is source control — the offending tooth must be extracted or undergo endodontic treatment and any collection drained; antibiotics alone cannot sterilise an established abscess and will fail without this. I would arrange urgent dental or oral-maxillofacial review for extraction or drainage. For analgesia and fever I would give paracetamol 15 mg/kg orally every four to six hours (maximum 60 mg/kg/day) and ibuprofen 5 to 10 mg/kg every six to eight hours. For the spreading cellulitis with systemic features I would give amoxicillin-clavulanate 45 mg/kg/day (amoxicillin component) orally in two divided doses, which covers oral streptococci and anaerobes. If he were unable to tolerate oral intake or were more unwell, I would admit for intravenous ampicillin-sulbactam 150 mg/kg/day (ampicillin component) in four divided doses, or clindamycin if penicillin-allergic. [1] [5]

(3) Safety-net advice (3). Give a concrete written plan: return immediately — even overnight — if he develops drooling or cannot swallow his saliva, difficulty opening his mouth, a changed or muffled voice, swelling under the chin or floor of the mouth, fast breathing or stridor, or if he simply looks more unwell. These are the red flags of Ludwig angina or deep space spread. Also arrange planned review at 48 to 72 hours if the swelling or fever has not improved, because failure to improve signals an undrained collection needing repeat dental and imaging assessment. Emphasise the need for dental follow-up to address the underlying caries and prevent recurrence. [2]

SAQ 2 (10 marks)

A 5-year-old girl presents with two days of worsening jaw and neck swelling, drooling, and difficulty opening her mouth. Her temperature is 39.2 degrees Celsius, she is sitting forward drooling saliva, holding her mouth open, and her voice sounds muffled. There is bilateral firm swelling under the jaw and the floor of the mouth is raised, firm and woody. She has a carious lower molar. She is tachypnoeic but has no stridor yet. [2] [3]

1. What is the diagnosis, and what makes this an airway emergency? (3) [2]
2. Outline your immediate resuscitation priorities in the emergency department. (4) [2] [3]
3. Discuss the definitive management and the pitfalls to avoid. (3) [1] [5]

Model answer — SAQ 2

(1) Diagnosis and airway threat (3). The diagnosis is Ludwig angina — a bilateral, rapidly spreading cellulitis of the submandibular, sublingual and submental spaces, arising from the carious lower molar. The features that make it an airway emergency are the bilateral submandibular swelling with a woody, indurated and raised floor of mouth, the elevated and displaced tongue, the drooling, trismus and the muffled voice. The cellulitis is in closed fascial spaces, so the floor of mouth feels hard rather than fluctuant, and the tongue is pushed upwards and backwards, progressively obstructing the airway at the tongue base. This is why drooling and a forward-sitting posture are danger signs — the child is maintaining her own airway. [2] [3]

(2) Immediate priorities (4). Airway is the first and overriding priority. Keep her sitting upright and leaning forward in a position she chooses; do not lay her flat and do not force an intraoral or oropharyngeal examination, because either can precipitate complete airway obstruction. Summon senior anaesthetic help, ENT and oral-maxillofacial surgery immediately, because intubation will be anatomically difficult and a surgical airway must be available as backup. Obtain intravenous access, take blood cultures and inflammatory markers, and start broad-spectrum intravenous antibiotics covering oral aerobes and anaerobes — ampicillin-sulbactam 150 mg/kg/day (ampicillin component) in four divided doses, or clindamycin 30 to 40 mg/kg/day with metronidazole 30 mg/kg/day added for deepest cover. Arrange contrast-enhanced CT of the neck and face only once the airway is secure and she is accompanied and monitored; imaging must not precede airway safety. [2] [3]

(3) Definitive management and pitfalls (3). Definitive management combines airway security, surgical source control and intravenous antibiotics in theatre — drainage of the involved spaces and extraction of the offending molar. The pitfalls are treating with antibiotics alone without source control (which fails for an established abscess); laying the child flat or forcing examination and precipitating obstruction; sending the child to imaging unaccompanied with a threatened airway; mistaking the cellulitis for a single drainable abscess when the floor of mouth is woody; and delaying anaesthetic and surgical involvement. Corticosteroids may be used adjunctively by the treating team to reduce oedema, but they are not a substitute for airway control, antibiotics and drainage. [1] [5]