NaOCl Concentration Risk — ORE Part 1 MCQ

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ModerateEndodonticsNaOCl Concentration RiskORE Part 1

During root canal treatment, which complication is of greatest concern when sodium hypochlorite at a concentration above 5% is inadvertently extruded beyond the root apex?

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Reveal the answer and explanation

Correct answer: B — Severe chemical injury to periradicular tissues

Explanation lettering: C = shown as A · A = shown as B · B = shown as C

The answer is A. Sodium hypochlorite is effective only while confined within the root canal; inadvertent extrusion into periradicular tissues can produce a severe chemical injury. Reported consequences of extruded concentrated NaOCl include immediate pain, swelling, haematoma, bruising and tissue necrosis. A concentration above 5% increases the potential severity of this toxic effect. B is incorrect because NaOCl has antimicrobial activity rather than reducing it. C is incorrect because smear-layer removal is principally achieved with a chelating agent such as EDTA, not NaOCl. D is not a recognised principal complication of apical NaOCl extrusion, and E is unrelated to the major safety risk.

Reference: Gernhardt CR, Eppendorf K, Kozlowski A, Brandt M. Toxicity of concentrated sodium hypochlorite used as an endodontic irrigant. International Endodontic Journal. 2004;37:272–280. https://pubmed.ncbi.nlm.nih.gov/15056354/