Which of these statements is true regarding alginate impressions?

The statement that alginate impressions can distort if stored improperly is true. Alginate is a hydrophilic material, meaning it can absorb moisture and deform if not handled or stored correctly. Proper storage typically involves keeping the impressions in a cool, moist environment to prevent them from drying out. If the impressions are allowed to dry, they can shrink and lose accuracy, compromising the quality of the dental cast made from the impression. This sensitivity to environmental conditions is crucial for dental professionals to understand when working with alginate materials.

In contrast, the other statements do not accurately reflect the best practices for handling alginate impressions. Storing them at high temperatures can further exacerbate distortion due to heat and moisture loss. Immediate trimming is not necessary, as impressions can be stored for a short period before trimming, provided they are kept moist. Additionally, alginate impressions are not reusable, as they cannot maintain their integrity or detail after being used once.