Oral histology and anatomy: dentine permeability: 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 · Oral histology and anatomy: dentine permeability

Sample item

Why is deep dentine near the pulp more permeable than superficial dentine near the enamel?

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

The answer and the reasoning

D. Tubules are wider and more closely packed near the pulp

Dentinal tubules are widest, about 2.5 micrometres, and most numerous per unit area near the pulp. Toward the junction they are narrower and fewer. Deep cavities therefore expose a larger tubule area, giving more fluid movement and a greater risk of pulp irritation.

Option by option

  • A. Tubules are filled with dense peritubular dentine near the pulp

    Peritubular dentine is thicker toward the outside and narrows the tubules there.

  • B. Predentine is absent in deep dentine

    Predentine is a layer lining the pulp in all regions, not absent at depth.

  • C. Intertubular dentine is thicker near the pulp

    Intertubular dentine occupies a smaller proportion of the area near the pulp.

  • D. Tubules are wider and more closely packed near the pulp (correct)

    Correct. Wide, closely packed tubules give high permeability near the pulp.

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 D, Tubules are wider and more closely packed near the pulp. Dentinal tubules are widest, about 2.

Why is "Tubules are filled with dense peritubular dentine near the pulp" not the answer?

Peritubular dentine is thicker toward the outside and narrows the tubules there.

Why is "Predentine is absent in deep dentine" not the answer?

Predentine is a layer lining the pulp in all regions, not absent at depth.

Why is "Intertubular dentine is thicker near the pulp" not the answer?

Intertubular dentine occupies a smaller proportion of the area near the pulp.

What concept does this question test?

It tests Oral histology and anatomy: dentine permeability in Dentistry. 5 micrometres, and most numerous per unit area near the pulp. Toward the junction they are narrower and fewer. Deep cavities therefore expose a larger tubule area, giving more fluid movement and a greater risk of pulp irritation.

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 Oral histology and anatomy: dentine permeability?

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.