Dental materials and radiology basics: composite curing depth: 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 · Dental materials and radiology basics: composite curing depth

Sample item

A 4-mm-deep cavity is filled with one bulk increment of light-cured composite cured for 20 seconds. A week later the deep part is soft and the restoration has debonded. Which technique is correct?

APlace and cure in increments of about 2 mmBEtch the dentine for longerCCure the surface for a shorter timeDUse a wider light tip with the same increment

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

The answer and the reasoning

A. Place and cure in increments of about 2 mm

Light penetration falls with depth, so thick layers stay under-cured at the base. Layers of about 2 mm also reduce shrinkage stress.

Option by option

A. Place and cure in increments of about 2 mm (correct)
Correct. Incremental placement ensures full polymerisation.
B. Etch the dentine for longer
Longer etching does not fix incomplete curing.
C. Cure the surface for a shorter time
A shorter cure makes polymerisation worse.
D. Use a wider light tip with the same increment
A wider tip does not make the light reach deeper.

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, Place and cure in increments of about 2 mm. Light penetration falls with depth, so thick layers stay under-cured at the base.

Why is "Etch the dentine for longer" not the answer?

Longer etching does not fix incomplete curing.

Why is "Cure the surface for a shorter time" not the answer?

A shorter cure makes polymerisation worse.

Why is "Use a wider light tip with the same increment" not the answer?

A wider tip does not make the light reach deeper.

What concept does this question test?

It tests Dental materials and radiology basics: composite curing depth in Dentistry. Layers of about 2 mm also reduce shrinkage stress.

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 Dental materials and radiology basics: composite curing depth?

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.