Restorative & Materials · single question
Which endodontic irrigant removes the smear layer from root canal walls?
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Correct answer: C. EDTA (ethylenediaminetetraacetic acid) — chelating agent that removes inorganic smear layer
- A. Formocresol is used in pulpotomy procedures — not as an irrigant for smear layer removal.
- B. Sodium hypochlorite dissolves organic tissue (pulp remnants, necrotic tissue) and has antimicrobial properties — but it does NOT remove the inorganic smear layer. NaOCl + EDTA together provide both organic dissolution and smear layer removal.
- C. Correct. EDTA is a chelating agent used as an endodontic irrigant specifically to remove the SMEAR LAYER (the debris layer of dentin particles, pulp remnants, and bacteria created during instrumentation). EDTA chelates calcium ions in dentin, demineralizing the smear layer. It is typically used after NaOCl irrigation.
- D. Camphorated phenol is used as an intracanal medicament for antimicrobial purposes between appointments — not for smear layer removal.
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