Dental anatomy: reactionary dentin: 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 · Dental anatomy: reactionary dentin

Sample item

Slowly progressing caries stimulates existing odontoblasts to lay down dentin beneath the lesion. What is this dentin called?

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

The answer and the reasoning

A. Reactionary (tertiary) dentin

Tertiary dentin forms locally in response to injury. Reactionary dentin is secreted by pre-existing odontoblasts, while reparative dentin comes from new odontoblast-like cells. Secondary dentin forms physiologically after root completion.

Option by option

  • A. Reactionary (tertiary) dentin (correct)

    Correct. Existing odontoblasts form reactionary dentin.

  • B. Secondary dentin

    Secondary dentin is physiological and not injury-driven.

  • C. Mantle dentin

    Mantle dentin is the first-formed outer layer.

  • D. Predentin

    Predentin is the unmineralised layer at the pulp border.

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.

More Dentistry questions

Questions about this Dentistry question

What is the answer to this Dentistry question?

The best answer is A, Reactionary (tertiary) dentin. Tertiary dentin forms locally in response to injury.

Why is "Secondary dentin" not the answer?

Secondary dentin is physiological and not injury-driven.

Why is "Mantle dentin" not the answer?

Mantle dentin is the first-formed outer layer.

Why is "Predentin" not the answer?

Predentin is the unmineralised layer at the pulp border.

What concept does this question test?

It tests Dental anatomy: reactionary dentin in Dentistry. Reactionary dentin is secreted by pre-existing odontoblasts, while reparative dentin comes from new odontoblast-like cells. Secondary dentin forms physiologically after root completion.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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 Dental anatomy: reactionary dentin?

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.