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Endodontics · patient case question

All of the following are used to irrigate the root canal system EXCEPT:

Patient case: Polymerisation stress, irrigation and occlusal guidance

Scenario: Three items.

  1. EDTA
  2. Chloroform
  3. Chlorhexidine
  4. Sodium hypochlorite
Show answer and explanation

Correct answer: B. Chloroform

  • A. EDTA is a chelator that removes the inorganic component of the smear layer and helps negotiate calcified canals.
  • B. Correct — this is the exception. Chloroform is a solvent used to dissolve gutta-percha during retreatment. It is not an irrigant, and it is both cytotoxic and a suspected carcinogen.
  • C. Chlorhexidine is used as an adjunct, valued for its substantivity, though it lacks tissue-dissolving capacity.
  • D. Sodium hypochlorite is the primary irrigant: it dissolves organic tissue and is strongly antibacterial.

Note: Never mix hypochlorite and chlorhexidine directly — the reaction produces an orange-brown parachloroaniline precipitate. Rinse with saline between them.

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