Community dentistry: dentine desensitising toothpaste: 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 · Community dentistry: dentine desensitising toothpaste

Sample item

A patient with dentine hypersensitivity is prescribed a toothpaste whose active ingredient diffuses along dentinal tubules and depolarises pulpal nerve endings. Which ingredient is this?

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

The answer and the reasoning

C. Potassium nitrate

Potassium ions from potassium nitrate diffuse through the tubules and depolarise the nerve endings, which blocks the transmission of pain impulses. Strontium salts and stannous fluoride act by occluding tubules. Calcium carbonate is an abrasive, and monofluorophosphate is an anticaries fluoride source.

Option by option

  • A. Sodium monofluorophosphate

    Monofluorophosphate supplies fluoride for caries prevention and is not a desensitiser.

  • B. Strontium chloride

    Strontium chloride acts by blocking the tubules, not by depolarising nerves.

  • C. Potassium nitrate (correct)

    Correct. Potassium ions depolarise the nerve and reduce its excitability.

  • D. Calcium carbonate

    Calcium carbonate is a mild abrasive used for cleaning.

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.

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Questions about this Dentistry question

What is the answer to this Dentistry question?

The best answer is C, Potassium nitrate. Potassium ions from potassium nitrate diffuse through the tubules and depolarise the nerve endings, which blocks the transmission of pain impulses.

Why is "Sodium monofluorophosphate" not the answer?

Monofluorophosphate supplies fluoride for caries prevention and is not a desensitiser.

Why is "Strontium chloride" not the answer?

Strontium chloride acts by blocking the tubules, not by depolarising nerves.

Why is "Calcium carbonate" not the answer?

Calcium carbonate is a mild abrasive used for cleaning.

What concept does this question test?

It tests Community dentistry: dentine desensitising toothpaste in Dentistry. Strontium salts and stannous fluoride act by occluding tubules. Calcium carbonate is an abrasive, and monofluorophosphate is an anticaries fluoride source.

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 Community dentistry: dentine desensitising toothpaste?

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.