Tooth development and dental anatomy: hypomaturation amelogenesis imperfecta: 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: hypomaturation amelogenesis imperfecta

Sample item

A 9-year-old has an inherited enamel defect. The crowns are of normal shape and the enamel is of normal thickness, but it is mottled yellow-brown, can be chipped away from the dentine, and on radiographs has about the same density as dentine. Which type is this?

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

The answer and the reasoning

D. Hypomaturation amelogenesis imperfecta

In hypomaturation amelogenesis imperfecta, enamel matrix is laid down normally but the crystals fail to mature, so thickness is normal and radiodensity is close to that of dentine. The enamel is soft enough to be chipped or pierced with a probe. Compare thin hard enamel in the hypoplastic type and very soft, low-density enamel in the hypocalcified type.

Option by option

  • A. Hypoplastic amelogenesis imperfecta

    Here the matrix is deficient, so the enamel is thin but hard, with open contacts and a radiopaque thin layer.

  • B. Dentinogenesis imperfecta type II

    This is a dentine disorder with opalescent grey-brown teeth and obliterated pulp chambers, not a primary enamel defect.

  • C. Hypocalcified amelogenesis imperfecta

    Here the enamel is of normal thickness but very poorly mineralised, wears rapidly and is less dense than dentine on films.

  • D. Hypomaturation amelogenesis imperfecta (correct)

    Correct. Normal thickness with failed maturation gives mottled, chipping enamel with density similar to dentine.

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, Hypomaturation amelogenesis imperfecta. In hypomaturation amelogenesis imperfecta, enamel matrix is laid down normally but the crystals fail to mature, so thickness is normal and radiodensity is close to that of dentine.

Why is "Hypoplastic amelogenesis imperfecta" not the answer?

Here the matrix is deficient, so the enamel is thin but hard, with open contacts and a radiopaque thin layer.

Why is "Dentinogenesis imperfecta type II" not the answer?

This is a dentine disorder with opalescent grey-brown teeth and obliterated pulp chambers, not a primary enamel defect.

Why is "Hypocalcified amelogenesis imperfecta" not the answer?

Here the enamel is of normal thickness but very poorly mineralised, wears rapidly and is less dense than dentine on films.

What concept does this question test?

It tests Tooth development and dental anatomy: hypomaturation amelogenesis imperfecta in Dentistry. The enamel is soft enough to be chipped or pierced with a probe. Compare thin hard enamel in the hypoplastic type and very soft, low-density enamel in the hypocalcified type.

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: hypomaturation amelogenesis imperfecta?

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.