Alginate impression problem

[lilodent]

Hello everyone

I am a dental student and need a bit of advice in regards to alginate impressions. I am making a removable partial denture for a patient, and taking the first impression was fine. However when taking the secondary impression (final one), i ended up forgetting the impression in the desinfection water. (I think the name of our disinfectant is presept).

So in our papers its written that the alginate impression can only be in the disinfectant water for 10 minutes and i think mine was in for 20 or 25 minutes. Will the distortion be too big for me to be able to use that impression?

I already could see that that a bit of the alginate on the side (only 1 cm) had gotten loose from the impression tray, but when i did the model it didn't seem very different from the first one. Actually by eye i couldn't see much difference.

Thank you everyone.

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[ysrebob]

Not sure about the extra 15 minutes underwater, but if the alginate pulled loose from your tray anywhere there's a pretty high chance the model is distorted, especially if the loose area was anywhere near abutment teeth, rests, or guide planes (ie anywhere the framework will touch teeth). And it doesn't take much distortion at all to make an alloy RPD framework not fit in the mouth no matter how hard you try to adjust it. If it's an alloy-framed RPD it would be worth your while to retake the impression if at all possible. Better that than have to remake the whole framework.

Now if its just an acrylic RPD (flipper), I might risk going ahead with the questionable impression if it's going to be an ordeal to get the patient back in.

 

[oralcare123]

Alginate impression should not be immersed in any case, only sprayed. You need to redo the impression

 

[lilodent]

Alginate impression should not be immersed in any case, only sprayed. You need to redo the impression

The thing is i have read about the spray method but at our dental school they tell us to immerse it?

 

[lilodent]

Not sure about the extra 15 minutes underwater, but if the alginate pulled loose from your tray anywhere there's a pretty high chance the model is distorted, especially if the loose area was anywhere near abutment teeth, rests, or guide planes (ie anywhere the framework will touch teeth). And it doesn't take much distortion at all to make an alloy RPD framework not fit in the mouth no matter how hard you try to adjust it. If it's an alloy-framed RPD it would be worth your while to retake the impression if at all possible. Better that than have to remake the whole framework.

Now if its just an acrylic RPD (flipper), I might risk going ahead with the questionable impression if it's going to be an ordeal to get the patient back in.

By alloy RPD and acrylic RPD you mean if im going to use alloy or acryl to put the teeth on? Also the distortion was at the back of the tray, so on the end of it where it seemed loose (around the wisedom tooth area) and the patient himself does not have any molar and is missing the 2nd premolar too on both sides. I do have a nice primary model of the area so could i use some novatray on the bad model and see if it fits the well taken first model?

 

[ysrebob]

By "alloy" I am just meaning a traditional RPD with a rigid cast metal framework. Fitting the framework depends so much on a really good and accurate master impression that if you're making this sort of denture you're probably just creating a lot of unnecessary work for yourself by not starting over with a new impression. I know the dental school hoops likely make it hard to schedule another impression, but suspect if you have a framework fabricated on the impression you have now, it will give you a lot of grief at try-in and you may never get it to seat right.

With a cheap all-acrylic "flipper" on the other hand (no metal framework, just an acrylic or resin base and a few wrought-wire claps) there is a little more room for error if you don't mind adjusting chairside.

 

[lilodent]

By "alloy" I am just meaning a traditional RPD with a rigid cast metal framework. Fitting the framework depends so much on a really good and accurate master impression that if you're making this sort of denture you're probably just creating a lot of unnecessary work for yourself by not starting over with a new impression. I know the dental school hoops likely make it hard to schedule another impression, but suspect if you have a framework fabricated on the impression you have now, it will give you a lot of grief at try-in and you may never get it to seat right.

With a cheap all-acrylic "flipper" on the other hand (no metal framework, just an acrylic or resin base and a few wrought-wire claps) there is a little more room for error if you don't mind adjusting chairside.

Around the incisors its alloy (metal base) and then in the molar region its acrylic, the loose area was in the molar region, but i guess it is the whole model that is distorted then? and what if i try the acryl on my primary model first and see that it also fits well on the distorted model would that make me safe?

 

[ysrebob]

The Peterkin Papers: "The Lady Who Put Salt in Her Coffee"
The Lady Who Put Salt in her Coffee.

 

[oralcare123]

The thing is i have read about the spray method but at our dental school they tell us to immerse it?

You should follow the instructions. If you made a mistake, then you should redo the impression

 

[lemoncurry]

Just my opinion, but why are you taking the final impression with alginate? I would use PVS, personally.

 

[schmoob]

How long was it from the time you took the impression to pouring?

Just like @lemoncurry mentioned, PVS would be better due to stability.