How long do alginate impressions last?

[NDPitch]

Long story short, we were doing alginate impressions on each other, and my stone pour came out pretty crappy. I was running late for a flight home so I just tossed the alginate impression/rimlock tray in my locker and took off. Will I be able to re-pour that impression when I get back from my break in about a week, or will I have to re-take the impression as well?

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[7 Iron]

You'll have to re-take it. Alginate impressions only stay accurate for 30 min-1 hour, and they need to be kept damp. They should be poured as soon as possible.

 

[Screwtape]

You'll have to re-take it. Alginate impressions only stay accurate for 30 min-1 hour, and they need to be kept damp. They should be poured as soon as possible.

+1

 

[NDPitch]

Thanks guys. I guess it's up to the clinic when I get back to take an impression on myself.

 

[charlestweed]

Next time, you should wrap them with moist paper towels and store them inside a sealed zip lock bag. That's what we do at our practice when we send the un-poured alginate impressions to the outside lab for making orthodontic study models, which don't require a high degree of accuracy. For ortho appliances such as retainers, expanders, space maintainers etc, we usually pour them right away. Ideally, you should pour the impressions within 30 minutes. From my experience, the appliances still fit perfectly even if we pour them 3-4 hours later. Make sure you wrap them with wet paper towels. If they are exposed to the air for a day, they will get hard like a rock and become unusable.