preliminary impressions for dentures - bubbles

[papadent]

Kept getting bubbles in my prelim impression for dentures today...was never a problem before, and i've been doing it the same way, but this time, recurrent air bubble, especially on the palatal area and the vestibular roll. Needless to say, I am a bit lost as to why this has suddenly started happening after having taken many good impressions before.

I was using regular-set alginate, with the monoject syringe along the vestibule and the palate.
Please let me know if you have any suggestions.

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[charlestweed]

The purpose of taking the preliminary impressions for denture is to make the custom impression trays; therefore, I don’t think it is a big deal to have a few bubbles here and there….unless you have a super picky instructor.

Did you use the measuring cup to get the right water:alginate powder ratio? Your alginate may have been too runny.... the material flow everywhere instead of going toward the vestibular roll. How about adding wax around impression tray?

 

[papadent]

as far as making the custom tray, the impression was more than good enough.
Unfortunately the instructor is quite picky
and yep, I did add wax, and the alginate was the right mixture. My only suspicion is maybe I was lifting the alginate as I seating it, as I sometimes heard air suctioning sounds.

 

[charlestweed]

How about trying to seat the impression tray from front to back? I know at schools, most of us are taught to go from back to front. First, I pull the patient’s lip away from the anterior teeth (in your case, the anterior edentulous ridge). Then, I push the impression tray toward the anterior vestibular roll. Then, I gently push the impression tray toward the posterior area and stop pushing on the tray when I start seeing a small excess amount of alginate material coming out of the posterior part of the tray……this way, I can prevent excessive amount of alginate material going toward the patient’s throat….and prevent gagging.

As an orthodontist, I take the alginate impression everyday and it is important for us to capture the oral vestibule and frenum attachments. I learned the above impression technique from my ortho director and it has worked well for me. To minimize patient’s discomfort, I like to use the quick set alginate.

 

[bigstix808]

as far as making the custom tray, the impression was more than good enough.
Unfortunately the instructor is quite picky
and yep, I did add wax, and the alginate was the right mixture. My only suspicion is maybe I was lifting the alginate as I seating it, as I sometimes heard air suctioning sounds.

try getting some cheek retractors. i've never needed them for impressions, but ihave seen others use them if they were having a hard time capturing adequate anatomy.

also, make sure you lift the lip up and go through your border movements and you might be able to "sqeeze" some of that air out.

 

[tinman831]

How about trying to seat the impression tray from front to back? I know at schools, most of us are taught to go from back to front. First, I pull the patient’s lip away from the anterior teeth (in your case, the anterior edentulous ridge). Then, I push the impression tray toward the anterior vestibular roll. Then, I gently push the impression tray toward the posterior area and stop pushing on the tray when I start seeing a small excess amount of alginate material coming out of the posterior part of the tray……this way, I can prevent excessive amount of alginate material going toward the patient’s throat….and prevent gagging.

As an orthodontist, I take the alginate impression everyday and it is important for us to capture the oral vestibule and frenum attachments. I learned the above impression technique from my ortho director and it has worked well for me. To minimize patient’s discomfort, I like to use the quick set alginate.

This is how I learned to do it as well. My school taught me to go from front to back as to reduce any air pockets being trapped in the palatal area. This can be remedied by placing a small bit of alginate on the palate first (as well as the vestibular area) prior to inserting the tray. OP, you should limit repositioning of the tray as it tends to distort the impression and can cause bubbles.

 

[Mackchops]

How about trying to seat the impression tray from front to back? I know at schools, most of us are taught to go from back to front. First, I pull the patient’s lip away from the anterior teeth (in your case, the anterior edentulous ridge). Then, I push the impression tray toward the anterior vestibular roll. Then, I gently push the impression tray toward the posterior area and stop pushing on the tray when I start seeing a small excess amount of alginate material coming out of the posterior part of the tray……this way, I can prevent excessive amount of alginate material going toward the patient’s throat….and prevent gagging.

As an orthodontist, I take the alginate impression everyday and it is important for us to capture the oral vestibule and frenum attachments. I learned the above impression technique from my ortho director and it has worked well for me. To minimize patient’s discomfort, I like to use the quick set alginate.

This is a good technique. You can also press with one hand and remove excess with a tongue depressor.

For the palate, I wouldn't worry. For the vestibules it could be a problem. Are you doing your border movements? You can also press on the outside of the lips and cheeks -- you need vestibular depth here, not thickness.

 

[jay47]

This is a good technique. You can also press with one hand and remove excess with a tongue depressor.

For the palate, I wouldn't worry. For the vestibules it could be a problem. Are you doing your border movements? You can also press on the outside of the lips and cheeks -- you need vestibular depth here, not thickness.

The best thing I every learned about alginate impressions is using a large syringe [http://img.diytrade.com/cdimg/39884...isposable_syringe_60ml_with_catheter_tip.jpg] to inject the material into the vestibule before placing the tray. Add a tiny bit more water, scoop/add the alginate into the large syringe, and squirt it into the vestibule and behind the second molars. This works really well for someone with a deep vestibule or protrusive maxilla (generally African American patients) and you can capture the whole thing nearly every time. After placing it into the vestibule, add the rest into the tray and moisten it by running it under the sink just a little and place into the mouth (back to front) to get everything. It has worked every single time I've done it and they usually turn out perfect.

For someone without a deep vestibule or protrusive maxilla, the technique mentioned above by the orthodontist should work well.

 

[Dr. Dai Phan]

Greetings and Happy Holidays,

Bubbles in the impression is likely due to water /saliva contamination or incomplete seating of the tray. This is what you should do:

1. Use slightly less water than recommended and use cold water.

2. Mix accordingly.

3. Smooth the impression surface with circular motion. You will need to moisten your gloves with water but not too much.

4. Shake off excess water (if any). During this time, tell patient to repeatedly swallow to clear any saliva in mouth.

5. Fully seat the impression from back to front to minimize material flowing to the back.

6. Now you should get a nice impression.

7. If you have tried twice and your professor is still not happy, ask him/her to show you. Sometimes they ask the students to do things that they can't do themselves. Hope this helps. DP

 

[mike3kgt]

Kept getting bubbles in my prelim impression for dentures today...was never a problem before, and i've been doing it the same way, but this time, recurrent air bubble, especially on the palatal area and the vestibular roll. Needless to say, I am a bit lost as to why this has suddenly started happening after having taken many good impressions before.

I was using regular-set alginate, with the monoject syringe along the vestibule and the palate.
Please let me know if you have any suggestions.

Are you using edentulous trays? I can't remember the last time I got voids in primary impressions with edentulous trays with rope wax periphery.

You could also ask the instructor to consider red cake compound for your primary impression. You can heat, water-bath, and place over and over again to get it perfect. You can also add grey/green stick compound if you really need to perfect your borders (for your primary cast??) if your instructor is that particular.

 

[NoPresident]

This is a complete shot in the dark, but a few months ago many students at my school started having similar problems. It turns out that the alginate being used by this particular group was past its expiration date (9 months over). Once this was realized and a new batch was brought in, problem solved!

 

[lemoncurry]

i heard from a classmate that if you get the pt to rinse with CHX before the impression it helps avoid bubbles. or was it listerine?

 

[YaoMingBU]

MIX UNDER VACCUUM!!!!!!!!!!!

after loading the tray, wet your finger and moisten the surface of the alginate - this reduces the surface tension.

 

[papadent]

Thanks for the suggestions everyone...Got my 2nd appointment coming up this week so I'll definitely try your recommendations.

 

[DavesNotHere]

MIX UNDER VACCUUM!!!!!!!!!!!

after loading the tray, wet your finger and moisten the surface of the alginate - this reduces the surface tension.

Do you really mix all your alginates in vacuum? We didnt even have that as an option in d school

 

[bigstix808]

Do you really mix all your alginates in vacuum? We didnt even have that as an option in d school

the only vac mixing i do is for master casts and fixed casts haha

for prelim ... snap stone all the way!