Tooth development and dental anatomy: origin of lateral canals: 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: origin of lateral canals

Sample item

Accessory (lateral) canals running from the pulp to the periodontal ligament are thought to arise how during root formation?

AOdontoclasts resorb a channel through the dentine after eruptionBTrauma opens the apex and leaves a communicating channelCSecondary dentine deposits unevenly and leaves gapsDA break in the root sheath lets a vessel remain in the forming dentine

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

The answer and the reasoning

D. A break in the root sheath lets a vessel remain in the forming dentine

If Hertwig's sheath develops a gap before it induces odontoblasts, no dentine forms at that point. A vessel can remain there and becomes a channel linking pulp and periodontium. Such canals can allow pulpal disease to spread to the periodontal ligament.

Option by option

A. Odontoclasts resorb a channel through the dentine after eruption
Odontoclasts resorb primary tooth roots, not create developmental channels in permanent roots.
B. Trauma opens the apex and leaves a communicating channel
Trauma does not create these developmental channels, which exist from root formation.
C. Secondary dentine deposits unevenly and leaves gaps
Secondary dentine narrows the pulp space and does not create canals.
D. A break in the root sheath lets a vessel remain in the forming dentine (correct)
Correct. A gap in the sheath leaves a channel that the vessel keeps open.

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 D, A break in the root sheath lets a vessel remain in the forming dentine. If Hertwig's sheath develops a gap before it induces odontoblasts, no dentine forms at that point.

Why is "Odontoclasts resorb a channel through the dentine after eruption" not the answer?

Odontoclasts resorb primary tooth roots, not create developmental channels in permanent roots.

Why is "Trauma opens the apex and leaves a communicating channel" not the answer?

Trauma does not create these developmental channels, which exist from root formation.

Why is "Secondary dentine deposits unevenly and leaves gaps" not the answer?

Secondary dentine narrows the pulp space and does not create canals.

What concept does this question test?

It tests Tooth development and dental anatomy: origin of lateral canals in Dentistry. A vessel can remain there and becomes a channel linking pulp and periodontium. Such canals can allow pulpal disease to spread to the periodontal ligament.

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: origin of lateral canals?

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.