Sodium hypochlorite extrusion injury — ORE Part 1 MCQ

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HardRestorative DentistrySodium hypochlorite extrusion injuryORE Part 1

During root canal irrigation of an upper premolar, a patient develops sudden severe pain, immediate facial swelling and bruising extending into the canine fossa. The needle had been wedged in the canal and irrigation was delivered under pressure. There is no history of latex sensitivity. What is the most likely diagnosis?

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Correct answer: E — Sodium hypochlorite extrusion injury

Explanation lettering: B = shown as A · D = shown as B · E = shown as D · A = shown as E

The diagnosis is sodium hypochlorite extrusion injury (A). The key clinical discriminators are: (1) immediate onset during active irrigation (not delayed); (2) sudden severe pain—characteristic of chemical tissue injury rather than inflammatory response; (3) rapid facial swelling and bruising extending to canine fossa—indicating extravasation into soft tissue planes; and (4) precipitating factor: pressurised delivery through a wedged needle. Sodium hypochlorite, when extruded beyond the apical foramen or through root perforations, causes acute chemical injury characterised by rapid edema, haematoma, and bruising. Option B (local anaesthetic allergy) would present with urticarial or anaphylactic features and would require prior sensitisation; allergy does not cause acute chemical necrosis. Option C (acute periapical granuloma) develops over weeks to months, not during treatment. Option D is excluded by the patient's negative latex history. Option E (alveolar osteitis) occurs post-extraction, typically 2–3 days after treatment, not intraoperatively. The combination of mechanism (pressurised irrigation), timing (immediate), and clinical presentation (acute chemical injury with rapid swelling/bruising) is pathognomonic for NaOCl extrusion.

Reference: Farook SA, Shah V, Lenouvel D, et al. Guidelines for management of sodium hypochlorite extrusion injuries. Br Dent J. 2014; 217(12): 679–684. https://pubmed.ncbi.nlm.nih.gov/25525012/