Can HC acrylic be cured in a pressure pot?

[gatorteeth87]

Getting frustrated with LC baseplates, have tried the split curing method and it seems to be better but I really want to start encouraging my doctors to do processed baseplates. Just seems like a lot of work, especially if the models don't survive packing. So I am wondering if it is possible to cure HC acrylic in a pressure pot at the manufacturer suggested temperature and time? Don't see why I couldn't do everything the same except skip packing and use the P.P.?

Would save a lot of time if it were possible!

 

[Flipperlady]

What's wrong with LC baseplates? I use the Triad Denture Material and love the stuff.
I wouldn't put the heat cured acrylic in a pressure pot unless you want a lot of porocity.
You could get a cheap vacuum machine and do the pull down baseplates.

 

[kcdt]

Getting frustrated with LC baseplates, have tried the split curing method and it seems to be better but I really want to start encouraging my doctors to do processed baseplates. Just seems like a lot of work, especially if the models don't survive packing. So I am wondering if it is possible to cure HC acrylic in a pressure pot at the manufacturer suggested temperature and time? Don't see why I couldn't do everything the same except skip packing and use the P.P.?

Would save a lot of time if it were possible!

Short answer, no. Long answer, go ahead and try it and then come back and tell us why it was a monumental waste of time.
I'll give you a hint: Swiss cheese. Insufficient density of material. Insufficient pressure during processing. Sound familiar?
There are specific reasons why heat cure requires a flask.

 

[droberts]

Ever give a thought to vacuum form base plates? Using .100 Clear Surgical stint material works really well, and provides a uniform thickness.

 

[AJEL]

The long way to make a great baseplate/wax rim super stable, you can thin it to .2mm over the ridge to ease tooth setting but it don't happen in 5 min.

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I still don't have the best handle on this picture thing when you click on the picture you have to go to prev button to go thru the series, I don't hink I need to put captions in for a technician to figure out what I'm doing. The material is Home - Vynacron Dental Resins, Inc. the mix is 10 powder 7 liquid pour per base 130' at 30psi. I keep the stuff in the fridge to extend pour time, The base is strong with a little flex & polishes easily. I tried rolling it on the master model a few times in a rush it works but sometimes breaks a delicate ridge.

 

[gatorteeth87]

Short answer, no. Long answer, go ahead and try it and then come back and tell us why it was a monumental waste of time.
I'll give you a hint: Swiss cheese. Insufficient density of material. Insufficient pressure during processing. Sound familiar?
There are specific reasons why heat cure requires a flask.

I thought this was what the Pressure Pot was supposed to resolve: porosity? Going to give it a try and examine it under the scope just to see what happens. My guess is that you're right, otherwise I would hear about more people doing it. Pretty new to removables here so I figured I would ask!

LC ends up being soooo thick but I suppose you can thin it down. I still want the patient to have the closest thing to final fit during wax try-in as possible. Also, the way I see it, acrylic shrinks by % so if you cure a thin layer of acrylic and cure another thin layer over it during processing, instead of removing the B.P. there should be less overall distortion from polymerization?

Could do cold cure but I then you probably wouldn't want to use it in the final denture base. Have read studies that Cold Cure acrylic has less thermal contraction though. So many factors--what to do, what to do....

 

[gatorteeth87]

The long way to make a great baseplate/wax rim super stable, you can thin it to .2mm over the ridge to ease tooth setting but it don't happen in 5 min.

[/URL][/IMG]
I still don't have the best handle on this picture thing when you click on the picture you have to go to prev button to go thru the series, I don't hink I need to put captions in for a technician to figure out what I'm doing. The material is Home - Vynacron Dental Resins, Inc. the mix is 10 powder 7 liquid pour per base 130' at 30psi. I keep the stuff in the fridge to extend pour time, The base is strong with a little flex & polishes easily. I tried rolling it on the master model a few times in a rush it works but sometimes breaks a delicate ridge.

Thanks for the pics, looks pretty slick! Do you use these in the final denture or remove after boil-out?

 

[rkm rdt]

I prefer Ajel's technique.

 

[gatorteeth87]

I prefer Ajel's technique.

Do you use the poured base in the final denture or just for the bite blocks?

 

[rkm rdt]

Actually I just use baseplate wax for everything.Biteblocks and tryins.

However if I were to use processed bases I would use Ajel's technique.

 

[AJEL]

The baseplates are removed during boilout, they are the closest to the finial without damaging the master models. The wax rim is made of my set-up wax. why do the wax 2x? Light cure cracks & breaks apart when thinned for setting teeth on the ridge, & an increasing population is becoming allergic to the activator in LC base materials.

 

[HDL Owner]

???????? why worry about a broken master cast? the "baseplate" is now your base! The foundation unpon which the denture is constructed. I pour a new model inside the finished baseplate. Immedately after boil out usually this base will lift of carefully! (bends some while hot, or under heat lamp) and not hurt new model, no worries about bonding new material to old base and no warpage.

 

[kcdt]

I thought this was what the Pressure Pot was supposed to resolve: porosity? Going to give it a try and examine it under the scope just to see what happens. My guess is that you're right, otherwise I would hear about more people doing it. Pretty new to removables here so I figured I would ask!

LC ends up being soooo thick but I suppose you can thin it down. I still want the patient to have the closest thing to final fit during wax try-in as possible. Also, the way I see it, acrylic shrinks by % so if you cure a thin layer of acrylic and cure another thin layer over it during processing, instead of removing the B.P. there should be less overall distortion from polymerization?

Could do cold cure but I then you probably wouldn't want to use it in the final denture base. Have read studies that Cold Cure acrylic has less thermal contraction though. So many factors--what to do, what to do....

The chemistry and polymerization time are completely different. The pressures needed to avoid porosity in HC is much greater- the AF manuals recommend 3000lbs as final closure on the flask. 2 bars in a pot isn't going to get it. On the other hand 2 bars is fine for autocure because the cycle is short. These resins really are completely different beasts.
You know, you can find LC base plates as thin as 1.4mm.

But your thinking on controlling the material distortion by curing in smaller masses has merit.

I also agree about using autocure bases. I'd be inclined to chuck them in favor of a HC base.

 

[kcdt]

an increasing population is becoming allergic to the activator in LC materials.

Really? This is the first I've heard of it, but I admit to being in hiding the last year or so.
Can you give me details? Or point me to a study? I may have to give some though to these if the problem is significant....

 

[kcdt]

???????? why worry about a broken master cast? the "baseplate" is now your base! The foundation unpon which the denture is constructed. I pour a new model inside the finished baseplate. Immedately after boil out usually this base will lift of carefully! (bends some while hot, or under heat lamp) and not hurt new model, no worries about bonding new material to old base and no warpage.

The baseplate is only the foundation if you don't toss it out, but instead laminate over it, so there's that.

If you're laminating over it, then softening it and removing it from the the flask are the last thing I'd do.

If you're tossing it, then I get your meaning.

However, pouring a new model inside the base might give you a decent rendition of the intaglio of the baseplate, but it is now one more step removed from the master model, the impression, and the mouth, so there's that.

 

[AJEL]

Really? This is the first I've heard of it, but I admit to being in hiding the last year or so.
Can you give me details? Or point me to a study? I may have to give some though to these if the problem is significant....

I seem to attract the different it seems, have you received reports on alergy patients from clifford?

Welcome to Clifford Consulting & Research online - North American english version

I have 3 DDS who send reports specific to patients & I need to check the custom tray, teeth , baseplate & Denture Material specific to color, with the report for acceptance or reactive & non acceptable. Even attachments, & reline material, right down to the cleaner used or disinfection used.

 

[AJEL]

???????? why worry about a broken master cast? the "baseplate" is now your base! The foundation unpon which the denture is constructed. I pour a new model inside the finished baseplate. Immedately after boil out usually this base will lift of carefully! (bends some while hot, or under heat lamp) and not hurt new model, no worries about bonding new material to old base and no warpage.

Maybe I'm old school but the inside of the base does not contain nearly the detail the model from a custom tray does, I take care not to scratch, buff or damage the master cast, I even try to get the DDS to use impression wax to make as perfect a post dam as possible, admittedly I don't get this all to often but I try. Unless your DDS uses your base as a finial custom tray after tryin, and as I remount after processing that is a pain.