Dental materials and radiology basics: water powder ratio of gypsum: 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: water powder ratio of gypsum

Sample item

A technician adds extra water to dental stone to make pouring easier. What is the effect on the finished cast?

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

The answer and the reasoning

A. Lower strength with a longer setting time

A higher water to powder ratio leaves fewer crystal nuclei per unit volume, so setting is slower and the set mass is more porous and weaker. Setting expansion also falls. Accurate measurement of water and powder is essential for reliable casts.

Option by option

  • A. Lower strength with a longer setting time (correct)

    Correct. Excess water weakens the cast and prolongs setting.

  • B. Greater strength because hydration is fuller

    Extra water does not strengthen the cast; the unreacted water leaves voids as it evaporates.

  • C. Unchanged strength because excess water evaporates

    Evaporating water leaves pores, so the strength falls and is not unchanged.

  • D. Shorter setting time with higher setting expansion

    More water slows setting and lowers setting expansion rather than raising it.

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, Lower strength with a longer setting time. A higher water to powder ratio leaves fewer crystal nuclei per unit volume, so setting is slower and the set mass is more porous and weaker.

Why is "Greater strength because hydration is fuller" not the answer?

Extra water does not strengthen the cast; the unreacted water leaves voids as it evaporates.

Why is "Unchanged strength because excess water evaporates" not the answer?

Evaporating water leaves pores, so the strength falls and is not unchanged.

Why is "Shorter setting time with higher setting expansion" not the answer?

More water slows setting and lowers setting expansion rather than raising it.

What concept does this question test?

It tests Dental materials and radiology basics: water powder ratio of gypsum in Dentistry. Setting expansion also falls. Accurate measurement of water and powder is essential for reliable casts.

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: water powder ratio of gypsum?

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.