What is the PRIMARY function of sodium hypochlorite as an endodontic irrigant?

Correct answer: C. Antimicrobial action combined with dissolution of organic pulp tissue

• A. Chelation of INORGANIC debris is the job of EDTA. NaOCl has essentially no effect on the mineral component; the two are used sequentially for this reason.
• B. Sealing is achieved by the obturation material and sealer, not by an irrigant.
• C. CORRECT. Sodium hypochlorite is the primary irrigant because it does two things nothing else does as well: it is broadly BACTERICIDAL (including against biofilm) and it DISSOLVES ORGANIC tissue — necrotic pulp remnants, collagen, and the organic component of the smear layer — allowing debridement of areas files cannot touch, such as isthmuses, fins and lateral canals.
• D. NaOCl does provide some lubrication, but that is incidental. Lubrication is not why it is the irrigant of choice.

Note: Standard sequence: NaOCl throughout instrumentation → EDTA for the smear layer → final NaOCl rinse. Never use NaOCl and chlorhexidine together — they precipitate parachloroaniline.