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Surgical Emphysema — MFDS Part 1 MCQ

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ModerateOral Surgery PrinciplesSurgical EmphysemaMFDS Part 1

During surgical removal of a mandibular third molar using an air-driven high-speed handpiece, a patient develops rapid unilateral facial and neck swelling. Palpation of the swelling produces crepitus. Which mechanism best explains this complication?

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Correct answer: D — Pressurised air entering the soft tissues and dissecting along fascial planes

The correct answer is D. Surgical emphysema occurs when pressurised air is introduced through a mucosal or surgical defect and dissects through the soft tissues and fascial planes. Air-driven handpieces are a recognised cause, particularly during surgical extraction of mandibular molars. Rapid swelling accompanied by palpable crepitus is the key discriminating feature. Intravascular local anaesthetic injection causes systemic neurological or cardiovascular toxicity rather than crepitant swelling. Foreign-body aspiration produces respiratory symptoms. Lingual artery injury may cause a rapidly enlarging floor-of-mouth haematoma, but the swelling would not be crepitant. A zygomatic arch fracture is unrelated to this operative mechanism and would not account for air tracking through the neck.

Reference: Jones A, Stagnell S, Renton T, Aggarwal VR, Moore R. Causes of subcutaneous emphysema following dental procedures: a systematic review of cases 1993–2020. British Dental Journal. 2021;231:493–500. https://pubmed.ncbi.nlm.nih.gov/34686817/