Lot of Bubbles in Dentures

[NICO DEnt]

Hey guys recently I start working as Dental technician and making dentures. I have made many dentures in the past using spofa heat cure acrylic (45 min full polymerization) and recently I bought Hereus Kulzer acrylic (45 min polymerization) and all the time when I flask with that acrylic the final work have bubbles traped inside the dentures. Any possible causes?

I read the manual and do it everything as it says, put powder with liquid in a plastic cup, close it to avoid air pass through, whait 6 min to be a dough and play with it for at least 1 min. Also I dry my flasks before put the acrylic and press it.

Please any advise is welcome...

Thanks and sorry if my english is bad

 

[Affinity]

dry flasks= bubbles in acrylic

 

[wwcanoer]

curing time not long enough???

 

[kcdt]

dry flasks= bubbles in acrylic

Not sure I follow the logic. Type 2 in a pressure pot, yeah, a dry model can cause issues.
Press pack type 1? I don't think so.
Insufficient trial packs are the most obvious culprit in type 1 resins.

 

[NICO DEnt]

So the flasks should have moisture? What's your advise? Gupsum should be rinsed with water before put the acrylic?

 

[Doris A]

Not enough acrylic in the flask will also cause porosity.

 

[Smilestyler]

Insufficient acrylic. Make sure you trial pack. (These are most likely)

Also some acrylic like to start out in the bath at room temp then brought up to curing temp for designated time. If you drop them into hot water right off the start the monomer can boil causing bubbles.

 

[kcdt]

So the flasks should have moisture? What's your advise? Gupsum should be rinsed with water before put the acrylic?

That's not your issue. Not with heat cure.
You're either not packing to sufficient density, or you're scaling up the heat too quickly.
Those are the main culprits in press pack type 1.
Wet or dry in this scenerio doesn't mean squat.

 

[kcdt]

Insufficient acrylic. Make sure you trial pack. (These are most likely)

Also some acrylic like to start out in the bath at room temp then brought up to curing temp for designated time. If you drop them into hot water right off the start the monomer can boil causing bubbles.

Excellent reply... I completely forgot about temperature shock.

 

[NICO DEnt]

That's not your issue. Not with heat cure.
You're either not packing to sufficient density, or you're scaling up the heat too quickly.
Those are the main culprits in press pack type 1.
Wet or dry in this scenerio doesn't mean squat.

I pack it to sufficient density, acrylic comes from the flasks after apply pressure. Then I place it in boiling water. Maybe the problem is that water temperature is to high(water is boiling more than 20 min)? What is the optimum temerature? If I bake it microwave is going to work better or not?

 

[Doris A]

You need to trial pack it, not just put too much acrylic in and close it once. The water should NOT be boiling when you put it in.
Put it in room temperature water and slowly bring it to a boil, then let it boil for 45 minutes.

 

[kcdt]

I pack it to sufficient density, acrylic comes from the flasks after apply pressure. Then I place it in boiling water. Maybe the problem is that water temperature is to high(water is boiling more than 20 min)? What is the optimum temerature? If I bake it microwave is going to work better or not?

You are not packing to sufficient density like that, I guarantee it.
If you don't understand press packing procedures here's some tutorials:


http://www.pua.edu.eg/PUASite/uploa...1/processing of complete denture - part 2.pdf

http://www.jpda.com.pk/effect-of-cu...e-on-porosity-in-acrylic-resin-denture-bases/

http://www.gcamerica.com/lab/products/NATURE-CRYL_HI20ET/brochure.pdf

Your porosity issue is caused by dropping it in boiling water straight away
and/or lack of trial packing.

Optimum water bath is 165˚F going from room temperature at 2˚/minute on a 9 hour timed cycle with a half hour boil at the end. UNLESS the manufacturer details specs different from this.

Don't microwave unless you have resin formulated for it. Too technique sensitive.

 

[kcdt]

I pack it to sufficient density, acrylic comes from the flasks after apply pressure. Then I place it in boiling water. Maybe the problem is that water temperature is to high(water is boiling more than 20 min)? What is the optimum temerature? If I bake it microwave is going to work better or not?

Are you interested in microwave?
You seem to be working under time constraints. Is this why the short cure times?

 

[Affinity]

I always heard the air in the model escapes into the acrylic would be my logic. Ive noticed it also when using dry models in a pressure pot.. maybe it was only with cold cure... I dont press pack, I use ivocap, never any bubbles.

 

[kcdt]

I always heard the air in the model escapes into the acrylic would be my logic. Ive noticed it also when using dry models in a pressure pot.. maybe it was only with cold cure... I dont press pack, I use ivocap, never any bubbles.

It happens in a pressure vessel with autocure, because you're forcing air in to create higher atmospheric pressure. If air is not purged from the model, it migrates to the surface as the pressure forces water into the gypsum.
This doesn't happen in a flask because the water is a heat exchange medium only. There's no air pressure forcing the water to displace atmosphere.
The pressure is direct mechanical force either to the flask itself or to an injection piston. Air pressure itself isn't the means providing compression DIRECTLY.
Does that make sense?

 

[Timmy]

When I was newbie in lab, I have mistake about monomer.
It's same thing when I was look, so mixed polymer with direct resin monomer.
It's a poor mistake but could be happen.
And too many bubbles appear that denture inside out.


Sent from my iPad using Tapatalk

 

[NICO DEnt]

Thank you guys for the time to answer my questions and enlighten me

 

[budgenator]

I was surprised that Paladon acrylic really can be processed by boiling for 40 min. Trial packing is critcal for processing boil-only acrylic, keep packing untill the acrylics looks clearish instead of pastey and let them set on the bench for at least 10 mins before you process. Keep the dentures thin, don't over-build and trim back post-process. I like processing against Yates&Motloid's plasticlear final closure sheets too.

 

[NICO DEnt]

I was surprised that Paladon acrylic really can be processed by boiling for 40 min. Trial packing is critcal for processing boil-only acrylic, keep packing untill the acrylics looks clearish instead of pastey and let them set on the bench for at least 10 mins before you process. Keep the dentures thin, don't over-build and trim back post-process. I like processing against Yates&Motloid's plasticlear final closure sheets too.

It is MelioDent from Heraeus Kulzer no Paladon. It is a economical heat cure acrylic resin. About trial pack, I should remove the plastic sheet before boiling or I can keep it in my last trial pack? In couple of videos I saw technicians remove it when doing the last trial pack, and leave it for couple of minutes waiting acrylic to escape from flask (as you mentioned above)

 

[kcdt]

It is MelioDent from Heraeus Kulzer no Paladon. It is a economical heat cure acrylic resin. About trial pack, I should remove the plastic sheet before boiling or I can keep it in my last trial pack? In couple of videos I saw technicians remove it when doing the last trial pack, and leave it for couple of minutes waiting acrylic to escape from flask (as you mentioned above)

Remove the sheet before you process.