Air bubbles, heat cure

[NoName]

Hello, I'm having issues with PlastoDon N (Scheftner) heat cure material, whenever there's thicker parts of the denture (usually under molars) I get air bubbles, sometimes few, sometimes a lot, I'll show you pics when there's a lot of them, I use to use Meliodent, it was great, there was no issues at all, so my thoughts on this is that I'm doing something wrong and so far I couldn't find what, here's my thoughts:

1. Too much monomer? but I do wait about 10min and the material itself seems good to go (like Meliodent was),when it's too soft - I wait a bit longer, when it's too hard - I try to put it in faster (lol..)
2. Maybe it's the temperature? I put the flask with the material inside into the boiling water, I try to put it into almost boiling water, so that the flask itself would absord the heat right before the water reaches boiling point.
3. Since air bubbles are mostly inside the thicker parts of the denture - I was thinking maybe I need to put the flask inside the boiling water faster? because the middle part of the flask reaches the temperature last, and usually the middle part is thickest

 

[kimba]

I would read the for the acrylic and

 

[kimba]

. would read the instructions for the acrylic and follow them precisely ie monomer polymer ratio and curing protocol . It looks like monomer bubbling in thicker parts. Start with instructions for new acrylic, not what you used to do with what you used to use that never gave you a problem

 

[NoName]

the thing with instructions is that there aren't any..I mean the product does not come with the instruction papers, the one sales rep gave me is just weird, I don't trust it, I tried if ofc, ratio was off, you couldn't even mix it.. I just doubt it's the real thing, I know few techs who use this material, they also get bubbles, only less than me, but sometimes I get only a few bubbles, sometimes none (when the denture is thin)

 

[JonnyLathe]

I'm not familiar with your system or acrylic but it kind of looks like it's underpacked. Are you sure you're using enough acrylic? Trial packing? That would make sense with it being mostly in the thicker areas and you not having this issue with thinner dentures.

I also generally wouldn't put heat cure straight into boiling water.

The optimal time to pack is when your acrylic kind of snaps a bit when you separate it.

 

[Doris A]

Look online for instructions for your acrylic. I agree with the other posters. It could be not enough acrylic, acrylic isn’t ready to be packed, or the water is too hot when you put it in the tank. You also need to pack it slowly, packing too quickly can cause porosity as well.

Edit: I looked on Scheftner’s website for instructions, I couldn’t find any. In my opinion, I would not use an acrylic that doesn’t come with specific instructions. Find another brand that tells you how to use it.

 

[Cleo]

I would adjust your temp down so it takes longer to boil. If it gets to a boil with too much residual monomer the monomer will do what liquid does and expand/boil creating air voids. Could also be under packed. I have tried tons of faster curing acrylics and the timing to boil is critical. Some of those 30 mimute monomers have to ramp up to boil over 30 to 45 minutes. Even with microwave flasks they dont go in at high power right away

 

[Smilestyler]

As stated already; don’t put it in boiling water. You should be using room temperature water then bring it up to boiling.

 

[NoName]

Instructions don't make sense, it says mix ratio is 10g of powder and 4ml of monomer..which is ridiculous, I tried that and only like 1/4 of polymer gets wet, because 4ml is not even close to enough lol, it also says that adding 5ml instead of 4ml will extend working time up to 2-3 hours, which is another bs..so that's why I don't follow the instructions..anyway today I had to make another denture, this time I tried less monomer, when I was mixing with spatula it was thick, you could mix it, but you could also feel that it's thick, but it was still good, it wasn't to a point where you could feel that it's hard to mix and you need more monomer and now I got better results, but still not good enough, but it's a start

 

[NoName]

so now my thoughts are that I need to use less monomer and wait a bit longer almost to a point where it's harder to put the dough inside the flask, also some of you mentioned that boiling water is bad, but the instruction says that this material is designed for fast heat curing and it says to put into boiling water for 20min..which I'd say is yet another bs..but who knows

 

[Doris A]

so now my thoughts are that I need to use less monomer and wait a bit longer almost to a point where it's harder to put the dough inside the flask, also some of you mentioned that boiling water is bad, but the instruction says that this material is designed for fast heat curing and it says to put into boiling water for 20min..which I'd say is yet another bs..but who knows

You need to change acrylics. Try Diamond D. If you need to process it quickly you can get microwave flasks and use their microwave monomer with their regular polymer.

 

[Flipperlady]

Need to trial pack more (little pea size amounts) and if possible let bench set (20 or thirty minutes) before processing. All the steps leading up when you are in a hurry, such as boil out, paint separator hurriedly pack before separator is dry enough and models are too warm ,then throw in the boiling pot after, causing steam to rise in under packed lingual area.

 

[bigj1972]

Are you sure you are using the matching monomer/polymer? Something doesn't look right. Like DorisA said, dump it in the trash. Use a better acrylic product.

Those bubbles look to be from polymerizing too hot, too fast.

 

[JKraver]

It looks like thermal shock to me. Honestly get a better acrylic. It doesn't need to be this hard.