Dental materials and radiology basics: composite restoration: 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 restoration

Sample item

A deep composite restoration placed in a single thick increment causes post-operative sensitivity and a gap at the cavity floor. Which property of composite causes this?

AHygroscopic expansion of acrylicBThermal expansion of amalgamCPolymerisation shrinkageDSetting expansion of gypsum

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

The answer and the reasoning

C. Polymerisation shrinkage

Composite shrinks when it polymerises, pulling away from the cavity wall and causing marginal gaps and sensitivity. Incremental placement reduces this stress.

Option by option

A. Hygroscopic expansion of acrylic
Acrylic water uptake is a feature of denture bases.
B. Thermal expansion of amalgam
Amalgam is not the material in this case.
C. Polymerisation shrinkage (correct)
Correct. Shrinkage on curing causes gaps and stress.
D. Setting expansion of gypsum
Gypsum expansion applies to casts, not restorations.

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 C, Polymerisation shrinkage. Composite shrinks when it polymerises, pulling away from the cavity wall and causing marginal gaps and sensitivity.

Why is "Hygroscopic expansion of acrylic" not the answer?

Acrylic water uptake is a feature of denture bases.

Why is "Thermal expansion of amalgam" not the answer?

Amalgam is not the material in this case.

Why is "Setting expansion of gypsum" not the answer?

Gypsum expansion applies to casts, not restorations.

What concept does this question test?

It tests Dental materials and radiology basics: composite restoration in Dentistry. Incremental placement reduces this 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 restoration?

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.