Tooth development and dental anatomy: fusion versus gemination: 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: fusion versus gemination

Sample item

A child has a wide mandibular incisor with a groove across the crown. Counting the teeth in that arch shows one tooth fewer than normal. What is the likely diagnosis?

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

The answer and the reasoning

C. Fusion of two adjacent tooth germs

In fusion, two developing tooth germs unite, so the count of teeth is reduced by one. In gemination a single germ tries to divide, producing a bifid crown but a normal tooth count.

Option by option

  • A. Dens evaginatum

    Dens evaginatum is an extra cusp-like enamel projection on the occlusal surface.

  • B. Concrescence

    Concrescence is union of roots by cementum after root formation, with separate crowns.

  • C. Fusion of two adjacent tooth germs (correct)

    Correct. A missing tooth in the arch with a wide crown indicates fusion.

  • D. Gemination of one tooth germ

    Gemination shows a bifid crown without reducing the number of teeth.

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, Fusion of two adjacent tooth germs. In fusion, two developing tooth germs unite, so the count of teeth is reduced by one.

Why is "Dens evaginatum" not the answer?

Dens evaginatum is an extra cusp-like enamel projection on the occlusal surface.

Why is "Concrescence" not the answer?

Concrescence is union of roots by cementum after root formation, with separate crowns.

Why is "Gemination of one tooth germ" not the answer?

Gemination shows a bifid crown without reducing the number of teeth.

What concept does this question test?

It tests Tooth development and dental anatomy: fusion versus gemination in Dentistry. In gemination a single germ tries to divide, producing a bifid crown but a normal tooth count.

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: fusion versus gemination?

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.