Prosthodontics MCQ Answer 53

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The correct answer is c. 1 and 3.

1. Is false. The smaller the water: powder ratio of the original investment water mixture, the greater the hygroscopic setting expansion.

2. Is true. In general, the less the W:P ratio and the longer the mixing time within practical limits, the greater is the setting expansion.

3. Is false. The greatest amount of hygroscopic setting expansion is observed if the immersion takes place before the initial set.

4. Is true. The longer the immersion of the investment in the water bath is delayed beyond the time of the initial set of the investment, the lower is the hygroscopic expansion.

5. Is true.

References:

Anusavice K: Philips’ Science of Dental Materials, 10^th Ed., WB Saunders, 1996.