Tooth development and dental anatomy: fractured accessory cusp and necrosis: 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: fractured accessory cusp and necrosis

Sample item

A 13-year-old has a sinus tract and swelling over a caries-free mandibular second premolar with an open apex. The middle of the occlusal table shows a small worn dentine spot, and a parent recalls a small prominence there that chipped off months ago. What explains the pulp necrosis?

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

The answer and the reasoning

A. Loss of an accessory cusp whose core held a pulp horn

A dens evaginatus is an enamel-covered accessory cusp, often in the middle of a premolar's occlusal surface, whose core may hold a pulp horn extension. Attrition or fracture exposes the pulp, which becomes necrotic, often before the apex has closed. Protecting the tubercle is part of prevention.

Option by option

  • A. Loss of an accessory cusp whose core held a pulp horn (correct)

    Correct. Exposure of a pulp horn after cusp loss lets bacteria reach the pulp of the immature tooth.

  • B. Deep invagination lined by thin enamel admitting bacteria

    That describes dens invaginatus, where an infolding of enamel and dentine opens near the crown.

  • C. Root dilaceration damaging the apical blood supply

    Dilaceration is a bend in the root and would not produce this occlusal wear pattern.

  • D. Cervical enamel extension creating a periodontal defect

    Cervical enamel extensions affect the furcation of molars, not premolar occlusal tables.

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 A, Loss of an accessory cusp whose core held a pulp horn. A dens evaginatus is an enamel-covered accessory cusp, often in the middle of a premolar's occlusal surface, whose core may hold a pulp horn extension.

Why is "Deep invagination lined by thin enamel admitting bacteria" not the answer?

That describes dens invaginatus, where an infolding of enamel and dentine opens near the crown.

Why is "Root dilaceration damaging the apical blood supply" not the answer?

Dilaceration is a bend in the root and would not produce this occlusal wear pattern.

Why is "Cervical enamel extension creating a periodontal defect" not the answer?

Cervical enamel extensions affect the furcation of molars, not premolar occlusal tables.

What concept does this question test?

It tests Tooth development and dental anatomy: fractured accessory cusp and necrosis in Dentistry. Attrition or fracture exposes the pulp, which becomes necrotic, often before the apex has closed. Protecting the tubercle is part of prevention.

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: fractured accessory cusp and necrosis?

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.