Tooth development and dental anatomy: formation of multiple roots: 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 · Tooth development and dental anatomy: formation of multiple roots

Sample item

A mandibular molar develops two roots rather than one. Which developmental event divides the single apical opening of the root trunk?

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

The answer and the reasoning

D. Tongue-like extensions of the epithelial diaphragm grow toward each other and fuse

In multirooted teeth, the epithelial diaphragm grows unequally and develops tongue-like extensions that meet and fuse across the opening, dividing it into two or three openings. A root then forms around each opening.

Option by option

  • A. The primary enamel knot divides into two signalling centres

    The enamel knot patterns cusps in the crown, not roots.

  • B. Mesenchyme grows into the stellate reticulum and separates the sheath

    The stellate reticulum is within the enamel organ and plays no role in dividing the root opening.

  • C. Two separate dental laminae contribute to the same tooth germ

    A single dental lamina gives rise to each tooth germ; two laminae would give two teeth.

  • D. Tongue-like extensions of the epithelial diaphragm grow toward each other and fuse (correct)

    Correct. Fusion of diaphragm extensions divides the opening and each part forms a root.

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, Tongue-like extensions of the epithelial diaphragm grow toward each other and fuse. In multirooted teeth, the epithelial diaphragm grows unequally and develops tongue-like extensions that meet and fuse across the opening, dividing it into two or three openings.

Why is "The primary enamel knot divides into two signalling centres" not the answer?

The enamel knot patterns cusps in the crown, not roots.

Why is "Mesenchyme grows into the stellate reticulum and separates the sheath" not the answer?

The stellate reticulum is within the enamel organ and plays no role in dividing the root opening.

Why is "Two separate dental laminae contribute to the same tooth germ" not the answer?

A single dental lamina gives rise to each tooth germ; two laminae would give two teeth.

What concept does this question test?

It tests Tooth development and dental anatomy: formation of multiple roots in Dentistry. A root then forms around each opening.

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 Tooth development and dental anatomy: formation of multiple roots?

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.