Paediatric dentistry: ankylosed primary 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 · Paediatric dentistry: ankylosed primary molar

Sample item

An 8-year-old has a primary molar lying below the occlusal plane of neighbouring teeth with a dull percussion note. What is the likely diagnosis?

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

The answer and the reasoning

B. Ankylosed (infraoccluded) primary molar

Ankylosis is fusion of cementum or dentin to bone, so the tooth fails to erupt with growth and appears submerged. A dull percussion note and lack of mobility are typical. Extraction may be needed if it blocks the successor.

Option by option

  • A. Normal exfoliation pattern

    Normal exfoliating teeth become mobile.

  • B. Ankylosed (infraoccluded) primary molar (correct)

    Correct. Infraocclusion with dull percussion fits.

  • C. Dentigerous cyst

    A dentigerous cyst surrounds an unerupted crown.

  • D. Dens invaginatus

    Dens invaginatus is a crown anomaly.

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, Ankylosed (infraoccluded) primary molar. Ankylosis is fusion of cementum or dentin to bone, so the tooth fails to erupt with growth and appears submerged.

Why is "Normal exfoliation pattern" not the answer?

Normal exfoliating teeth become mobile.

Why is "Dentigerous cyst" not the answer?

A dentigerous cyst surrounds an unerupted crown.

Why is "Dens invaginatus" not the answer?

Dens invaginatus is a crown anomaly.

What concept does this question test?

It tests Paediatric dentistry: ankylosed primary molar in Dentistry. A dull percussion note and lack of mobility are typical. Extraction may be needed if it blocks the successor.

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 Paediatric dentistry: ankylosed primary 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.