Tooth development and dental anatomy: ectopic eruption of the first molar: 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: ectopic eruption of the first molar

Sample item

A 6-year-old has a bitewing showing a maxillary first permanent molar caught under the distal bulge of the second primary molar, whose distal root shows scalloped resorption. The permanent molar is tilted and will not come into occlusion. What is the diagnosis?

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

The answer and the reasoning

B. Ectopic eruption of the first permanent molar

In ectopic eruption the first permanent molar erupts along an abnormal path and resorbs the distal root of the second primary molar. It may self-correct but a stuck tooth needs separation or a brass wire.

Option by option

  • A. Dentigerous cyst of the first permanent molar

    A dentigerous cyst gives a well-defined pericoronal radiolucency around the crown.

  • B. Ectopic eruption of the first permanent molar (correct)

    Correct. The impacted erupting molar resorbs the distal root of the primary molar.

  • C. Ankylosis of the second primary molar

    Ankylosis causes infraocclusion of the primary molar, not scalloped resorption by an erupting tooth.

  • D. Internal resorption of the second primary molar

    Internal resorption begins inside the pulp chamber as a round expansion, not on the outer distal 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 B, Ectopic eruption of the first permanent molar. In ectopic eruption the first permanent molar erupts along an abnormal path and resorbs the distal root of the second primary molar.

Why is "Dentigerous cyst of the first permanent molar" not the answer?

A dentigerous cyst gives a well-defined pericoronal radiolucency around the crown.

Why is "Ankylosis of the second primary molar" not the answer?

Ankylosis causes infraocclusion of the primary molar, not scalloped resorption by an erupting tooth.

Why is "Internal resorption of the second primary molar" not the answer?

Internal resorption begins inside the pulp chamber as a round expansion, not on the outer distal root.

What concept does this question test?

It tests Tooth development and dental anatomy: ectopic eruption of the first molar in Dentistry. It may self-correct but a stuck tooth needs separation or a brass wire.

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 Tooth development and dental anatomy: ectopic eruption of the first molar?

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.