pressure pot results

[Hume Dental]

Hi
I've started making splints and curing them in the pressure pot with air and water.
How crucial is the amount of water and temperature and how does the water, technically affect the result?

I was told by a lab tech that he gets a better result without the water and just the air pressure. After trying this I ended up with sections of the splint that were still soft.

Would this have been the result of no water?

 

[droberts]

For any repairs, splints etc. I completely have the appliance covered in water. The temp at 120 degrees and the pressure at 17lbs.

 

[TomZ]

Water helps transfer heat, which sustains the curing reaction somewhat. So I cover also.
My rule, 120 degrees, 20psi, for 20min.

 

[the lab lady]

I put about and inch or two of water, with the model not in contact with the water (like steaming it) at about 17 lbs pressure, and 120 degrees.

 

[VictoryDental]

Water helps transfer heat, which sustains the curing reaction somewhat. So I cover also.
My rule, 120 degrees, 20psi, for 20min.

Same Here

 

[Hume Dental]

What causes the white porosity through the acrylic after I take it out of the pot?
Is it curing to fast? Or do the models on the articulator need to be wet before I close the bite and place it in the pot?

 

[XxJamesAxX]

Water helps transfer heat, which sustains the curing reaction somewhat. So I cover also.
My rule, 120 degrees, 20psi, for 20min.

Same here unless I'm using our 2nd pressure pot and then its at what ever psi the blow off valve pops at due to the guage being broke. Somewhere around 28-30 I suppose....

 

[XxJamesAxX]

What causes the white porosity through the acrylic after I take it out of the pot? Is this with using water in the pot? Acrylic didn't get to dry did it?
Is it curing to fast?Dont think so.
Or do the models on the articulator need to be wet before I close the bite and place it in the pot? I always soak models atleast 10min.[/QUOTE]

Answer is quote....

 

[DentureDude]

always use water in your pot.

water helps to leach out the monomer so the patient doesn't end up with monomer burns on the tissue. (change the water at least once a week).

cure anything and everything at least 20-30 min.

follow the manufactures directions for the products you are using.

 

[droberts]

What causes the white porosity through the acrylic after I take it out of the pot? Is this with using water in the pot? Acrylic didn't get to dry did it?
Is it curing to fast?Dont think so.
Or do the models on the articulator need to be wet before I close the bite and place it in the pot? I always soak models atleast 10min.[/QUOTE]

Answer is quote....

Soak your model for at least 15 minutes prior to the repair.

 

[Jo Chen]

The acrylic needs to be under water because it moderates the exothermic reaction of the curing acrylic. Not enough water and or too hot water will cause porosity because the acrylic gets too hot and starts boiling while curing. This causes porosity.
120 fahrenheit water starts the curing but also cools the acrylic during later stages of curing.
And yes, water your models before applying acrylic. Use trimmer water for the soaking because straight tap water will erode your model.

 

[AJEL]

Some great advice here so I might add my thoughts. 1st Check the MFG for mix ratio, time, & temp, and if you have a pressure pot with heat, preheat the water and check it with a probe from time to time. Turning the heat on after insertion will cause the bottom to ofer heat. DENTALNY Pressure Pot / 8 Quart w/ Reg & Heater : Denture Injector Not that guages go bad or break but I check stuff only because I bought stuff to check it with and hate waste.
If you are using ortho PMA YR probabily at 120*f around 15-20 psi 10-15 min
If you are using Products - Vynacron Dental Resins, Inc. U might need 140 around 29psi 30min
For BPMA ASTRON Dental Lake Zurich, IL. USA 800-323-4144 128*-130* 30 psi and very heat sensitive, over heat & bubbles not enough soft spots.
Also goes for Great Lakes Orthodontics :: Search
For some PMMA's Fricke Dental - Home repair, pour, flexible can be a bit different but accurate heat & 17-30 psi is common.
I use Denplus - quite a bit very color stable (I relined a 15yr old denture today & it still matched) but the material uses 150* @ 50psi for 1hr.
Remember when you pour in hydrocoloid the hydrocoloid is a buffer & an extra 15 min is safe if your pressure pot holds or maintains heat.
You do not want to put your pot on a heat source as the bottom will over heat & you could discover the problem we had with vulconizers back in the day (boom).
If your seperator is really good you can dry process but when you do wet process remember seperator can sometimes bubble and it is a good idea to lightly china brush the surface to insure you won't have a void (between the model and your acrylic base.) If you try pouring flippers, bruxes, dentures U can improve pour time by keeping the powder & monomer cold rather than adding more liquid. Measure accurately, for best results. Oboy I'm sure wordy tonight I best get back to work.
If U don't like the smell of trimmer slurry water or the slimy feel, U can create a super saturated water by just putting some old models in a jar of water and using that. Always presoak in a non leaching water.
OK we all like pictures here are some processed baseplates.

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[DentureDude]

Ajel, thanks for the great tips and pics.
man thats one high-tec looking pressure pot... what is that thing?

 

[AJEL]

Ajel, thanks for the great tips and pics.
man thats one high-tec looking pressure pot... what is that thing?

Which one:

DENTALNY Pressure Pot / 8 Quart w/ Reg & Heater : Denture Injector
is good for 3 bar & temperature control & up to 4 flasks, I like and use it in combination with the hedent unit.

The Whaldent Perform system built by Hedent of Germany has been discontinued about 15 years, It is useful up to 9bar & 80*c although I usually have it set at 4bar & 45*c. I had it rebuilt this July by Garreco They sometimes see a used one come around (in 1988 system was $15,000).

check out their PERform Tooth Sieve if U don't have one spend the money U will be really glad U did.
so what R U using?

 

[DentureDude]

ive got the almore pot.

seems to work ok.

that Whaldent pot looks awesome. dont make em like they used to!


ive often wondered if a vacuum pot would work?, instead of a pressure pot...

what do ya think?


ps. i really like the Garreco plaster and stone. great stuff.. really consistant.

 

[AJEL]

ive got the almore pot.

seems to work ok.

that Whaldent pot looks awesome. dont make em like they used to!


ive often wondered if a vacuum pot would work?, instead of a pressure pot...

what do ya think?


ps. i really like the Garreco plaster and stone. great stuff.. really consistant.

I like your pot, looks like my TCS, I added rubber feet to it. so it wouldn't scratch my stainless benches/tables.
We tried vacuum domes back in the 70's the acrylic looked like sponges.

 

[DentureDude]

We tried vacuum domes back in the 70's the acrylic looked like sponges.

interesting.. i wonder if anyone has tried pulling a perfect vacuum on a chamber (pot) with water and heat?

 

[AJEL]

interesting.. i wonder if anyone has tried pulling a perfect vacuum on a chamber (pot) with water and heat?

Here is one for you the original Whaldent system had the pressure pot, a vacume pomp set at -1.5bar (25ml) the flasks had a suction valve on the base, you would during cure have a vacume in the flaskbase and in the pressure pot there was a series of fittings to maintain the vacume in the base while there was pressure all around. Using the Perform PMMA. Cure was at 7bar & -1.5 bar 60*c 1 hour. You can get the PMMA from Garreco, it is some sweet strong stuff but pricey, it has been reformulated to cure at 45psi (3bar) 142*f 58*c 1hr. Very color stable no amines both FDA & CE2002 certs.
In the first picture you can still see the internal vaccume valve connections currently in the safe side position near the top.

 

[chief26]

I think the best person to ask would b ur acrylic manufactor...i use a separator..dry model..there is water n my pot but my model sits on a shelf and doesnt touch the water. This is what i learned at great lakes...it may b diffrent if ur not using a pre regulated heated pressure pot...the white stuff may b acrylic that didnt get enough monomer if u r not pouring or premixing the acrylic...when the model is wet and not placed underwater u will get large airbubbles. Hope it helps..