Caries, pulp and periodontal disease: EDTA in endodontics: practice question

A Dentistry question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Dentistry · Caries, pulp and periodontal disease: EDTA in endodontics

Sample item

During canal irrigation, 17 percent EDTA is used as a final rinse after sodium hypochlorite. What is its main purpose?

ATo dissolve the organic pulp tissue in the canalBTo remove the inorganic part of the smear layer by chelating calciumCTo disinfect the canal permanently by releasing chlorineDTo obturate the canal with a radiopaque filling

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

B. To remove the inorganic part of the smear layer by chelating calcium

Sodium hypochlorite dissolves organic tissue, while EDTA chelates calcium and removes the inorganic smear layer, opening dentinal tubules. Used together they clean the canal more effectively. EDTA should not be left in contact for long because it can erode dentine.

Option by option

A. To dissolve the organic pulp tissue in the canal
Organic pulp tissue is dissolved mainly by sodium hypochlorite.
B. To remove the inorganic part of the smear layer by chelating calcium (correct)
Correct. EDTA chelates calcium and strips the inorganic smear layer.
C. To disinfect the canal permanently by releasing chlorine
Chlorine release is a property of hypochlorite, not EDTA.
D. To obturate the canal with a radiopaque filling
Canal obturation uses gutta-percha and sealer.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this Dentistry question

What is the answer to this Dentistry question?

The best answer is B, To remove the inorganic part of the smear layer by chelating calcium. Sodium hypochlorite dissolves organic tissue, while EDTA chelates calcium and removes the inorganic smear layer, opening dentinal tubules.

Why is "To dissolve the organic pulp tissue in the canal" not the answer?

Organic pulp tissue is dissolved mainly by sodium hypochlorite.

Why is "To disinfect the canal permanently by releasing chlorine" not the answer?

Chlorine release is a property of hypochlorite, not EDTA.

Why is "To obturate the canal with a radiopaque filling" not the answer?

Canal obturation uses gutta-percha and sealer.

What concept does this question test?

It tests Caries, pulp and periodontal disease: EDTA in endodontics in Dentistry. Used together they clean the canal more effectively. EDTA should not be left in contact for long because it can erode dentine.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Caries, pulp and periodontal disease: EDTA in endodontics?

Learn the dental formula, eruption ages and tooth structure once, as tables. Then use the flashcards and the other Dentistry questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.