Sodium hypochlorite performs all of the following functions EXCEPT:

Correct answer: D. Chelating inorganic material and removing the smear layer

• A. It is a potent broad-spectrum antimicrobial, active against the anaerobes and against Enterococcus faecalis at higher concentrations.
• B. It provides lubrication as a flushing solution during instrumentation.
• C. This is its principal function — hypochlorite dissolves necrotic pulp tissue and organic debris, which no other common irrigant does effectively.
• D. CORRECT — this is the exception. Sodium hypochlorite is NOT a chelating agent. It has no capacity to bind calcium and therefore cannot dissolve the inorganic portion of the smear layer. That role belongs to EDTA (17%) or citric acid.

Note: The single most frequently tested fact about sodium hypochlorite is what it does NOT do: it does not chelate. Guard against hypochlorite accident — sudden severe pain, rapid swelling and ecchymosis on extrusion beyond the apex.