Alginate Pouring Time — MFDS Part 1 MCQ

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EasyDental MaterialsAlginate Pouring TimeMFDS Part 1

A conventional, non-extended-pour alginate impression has been disinfected according to local protocol. To maximise dimensional accuracy, when should it be poured in dental stone?

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Correct answer: A — Immediately after disinfection

The correct answer is A. Conventional alginate impressions should be poured as soon as practicable after disinfection, ideally within approximately 10 minutes, because they are dimensionally unstable. Syneresis causes water loss and shrinkage, while imbibition causes water uptake and expansion. Delaying pouring for 24 hours or 1 week therefore risks distortion, and immersion in water or exposure to air worsens dimensional change. Complete gelation occurs before the impression is removed from the mouth, so no further 24-hour setting period is required. Some specifically formulated extended-pour alginates can remain accurate for longer, but their permitted storage and pouring interval must follow the manufacturer's instructions; the stem explicitly excludes these products.

Reference: Niyazi AA et al. Comparative Analysis of Alginate Dimensional Stability with Varied Pouring Intervals. Journal of Pharmacy and Bioallied Sciences. 2024;16(Suppl 5):S4599-S4603; epub 30 January 2025. https://pubmed.ncbi.nlm.nih.gov/40061795/