Orthodontics: vitamin D-resistant rickets: 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 · Orthodontics: vitamin D-resistant rickets

Sample item

A 4-year-old with short stature and bowed legs has recurrent dental abscesses without caries or trauma. Radiographs show large pulp horns that reach the dentinoenamel junction. Which disease is likely?

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

The answer and the reasoning

C. X-linked hypophosphataemic rickets

In X-linked hypophosphataemic rickets, defective dentine with interglobular spaces and tall pulp horns allows bacteria to reach the pulp through microcracks, causing spontaneous abscesses. Treatment is phosphate and active vitamin D.

Option by option

  • A. Osteogenesis imperfecta

    Osteogenesis imperfecta has blue sclerae and fractures, with opalescent teeth.

  • B. Nutritional rickets

    Nutritional rickets would respond to vitamin D alone and is less linked to this dental pattern.

  • C. X-linked hypophosphataemic rickets (correct)

    Correct. Abscesses on intact teeth with tall pulp horns are characteristic.

  • D. Achondroplasia

    Achondroplasia has short limbs without dentine defects.

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 C, X-linked hypophosphataemic rickets. In X-linked hypophosphataemic rickets, defective dentine with interglobular spaces and tall pulp horns allows bacteria to reach the pulp through microcracks, causing spontaneous abscesses.

Why is "Osteogenesis imperfecta" not the answer?

Osteogenesis imperfecta has blue sclerae and fractures, with opalescent teeth.

Why is "Nutritional rickets" not the answer?

Nutritional rickets would respond to vitamin D alone and is less linked to this dental pattern.

Why is "Achondroplasia" not the answer?

Achondroplasia has short limbs without dentine defects.

What concept does this question test?

It tests Orthodontics: vitamin D-resistant rickets in Dentistry. Treatment is phosphate and active vitamin D.

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 Orthodontics: vitamin D-resistant rickets?

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.