Tooth development and dental anatomy: ectodermal dysplasia: 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: ectodermal dysplasia

Sample item

A 5-year-old boy has sparse hair, absent sweating with heat intolerance, and conical teeth with only a few teeth erupted. Radiographs show many missing tooth germs. What is the most likely diagnosis?

AHypohidrotic ectodermal dysplasiaBCleidocranial dysplasiaCAmelogenesis imperfectaDDown syndrome

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

The answer and the reasoning

A. Hypohidrotic ectodermal dysplasia

Hypohidrotic ectodermal dysplasia is an X-linked disorder of ectodermal structures. It features sparse hair, reduced sweating, hypodontia or anodontia, and conical teeth.

Option by option

A. Hypohidrotic ectodermal dysplasia (correct)
Correct. Sparse hair, anhidrosis and hypodontia with conical teeth define this condition.
B. Cleidocranial dysplasia
Cleidocranial dysplasia shows clavicle defects and supernumerary teeth, not anhidrosis.
C. Amelogenesis imperfecta
Amelogenesis imperfecta affects enamel only and does not cause hair or sweat gland defects.
D. Down syndrome
Down syndrome can show hypodontia, but not anhidrosis and sparse hair.

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.

Questions about this Dentistry question

What is the answer to this Dentistry question?

The best answer is A, Hypohidrotic ectodermal dysplasia. Hypohidrotic ectodermal dysplasia is an X-linked disorder of ectodermal structures.

Why is "Cleidocranial dysplasia" not the answer?

Cleidocranial dysplasia shows clavicle defects and supernumerary teeth, not anhidrosis.

Why is "Amelogenesis imperfecta" not the answer?

Amelogenesis imperfecta affects enamel only and does not cause hair or sweat gland defects.

Why is "Down syndrome" not the answer?

Down syndrome can show hypodontia, but not anhidrosis and sparse hair.

What concept does this question test?

It tests Tooth development and dental anatomy: ectodermal dysplasia in Dentistry. It features sparse hair, reduced sweating, hypodontia or anodontia, and conical teeth.

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: ectodermal dysplasia?

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.