Microwave Denture Curing

[kcdt]

Here's literature on Justi's miracle flask (the HK type):



"It will withstand extreme pressure under a hydraulic or hand press up to 3000 psi.."

You can see from this why I like this HK type the best. They are very robust.

Anyway, I hope that shed some light on this.....

 

[Irishtech]

Hi Guys ,
dont want to be a wise guy but are these really expensive flasks and special acrylic necessary ? I've been experimenting in the last few weeks and results are very promising with self clamping aluminium flasks and Vertex acrylic - Denture Processing Using A Microwave

comments/ questions welcome here or by email,
Hugh.

 

[kcdt]

Hi Guys ,
dont want to be a wise guy but are these really expensive flasks and special acrylic necessary ? I've been experimenting in the last few weeks and results are very promising with self clamping aluminium flasks and Vertex acrylic - Denture Processing Using A Microwave

comments/ questions welcome here or by email,
Hugh.

Well, just offhand, you do have the problem with metal blocking some of the microwave penetration, and, while the results LOOK promising, without some materials testing for strength, hardness, surface texture, etc., you have no real way of knowing whether or not the material polymerized in this fashion will meet the required or promised specifications.
IF, however, you've managed to come up with a protocol that DOES meet the standards, then you are on to something. I've just given up on thinking that playing mad scientist on my own is a viable thing to do- these are medical devices after all.

 

[Anziano]

Do any technicians out there that cure using the microwave use silicone around the teeth like one can using a conventional flask and boiling?

I use Dentsulate and Silicone for conventional curing, and I do not want to try it with microwave curing on an actual patient case without asking or doing a test denture first. Thanks!

 

[kcdt]

The only problem I have with the densulate is the material itself. I don't care for it. However, you can use PVS or lab putty and it'll be fine. I use lab putty to do rebase.
I like stone (flowstone) just fine, but you can use a couple of viscosities of pvs and get really out standing results. You just have to account for the extra expense, capish?

 

[leetech]

hi Kcdt


How and were would you use PVS to gain an improvemnet and also should a certain shore hardness be used.

At what stage do you usually pack the GC acrylic, as the instructions quote a time, but temperatures change etc in the lab.


regards lee

 

[kcdt]

How and where: http://dentallabnetwork.com/forums/f2/need-advice-ivocap-processed-dentures-9685/
check this thread out #3 is what you're looking for, plus there are some links further down that offer how to along those lines.

As far as when to pack. Well, I'm old school and if I'm compression molding I want it at doughy but not sticky; if it snaps you've let it go too far. here in the tropics that can be as little as 5 minutes.

You're always better off gauging the material yourself until you get a feel for time/temp variances...

 

[Flipperlady]

I'm going to try and microwave the 199 next week. I'll do a couple of experimental cases first. I'll try to calibrate, but I know to set the microwave on medium for naturcryl mc, and guess the 199 will work on that setting too. Instructions say to bench set for 30 min, microwave for 15 and cool in water for 15min.
I let everyone know if i have sucess If someone else has tried this please let me know.

 

[XxJamesAxX]

I'm going to try and microwave the 199 next week. I'll do a couple of experimental cases first. I'll try to calibrate, but I know to set the microwave on medium for naturcryl mc, and guess the 199 will work on that setting too. Instructions say to bench set for 30 min, microwave for 15 and cool in water for 15min.
I let everyone know if i have sucess If someone else has tried this please let me know.

Flipper,

Which microwave flask do you have? I've often thought about trying the microwave but have yet to get any flask to try it with... Thanks and look forward to hearing your results.

James

 

[Flipperlady]

I'm using the Buffalo and Acron GC flasks.
I look forward to seeing my results too! I'll post here, but it will be next week sometime.

 

[Jmichael]

I have the Success microwave flask, among others. I have given up on microwaving L199 due to poor results. I much prefer the GC Naturecryl microwave material.

 

[Flipperlady]

I mostly want to microwave 199 for relines to match dentures made with 199 and thin appliances such as flippers. Thicker dentures would take the Naturecryl and traditioanl cure 199. Did you follow the instructions to the letter (calibrate, bench set etc.....?) I'm going to put mine on medium (same setting as for Naturecryl , let bench set and follow cure times etc..... I'm not going to try this on an actual case just yet, i would have a seizure if I had a reline full of porosity. I'm also press packing, no injection.

 

[Jmichael]

I mostly want to microwave 199 for relines to match dentures made with 199 and thin appliances such as flippers. Thicker dentures would take the Naturecryl and traditioanl cure 199. Did you follow the instructions to the letter (calibrate, bench set etc.....?) I'm going to put mine on medium (same setting as for Naturecryl , let bench set and follow cure times etc..... I'm not going to try this on an actual case just yet, i would have a seizure if I had a reline full of porosity. I'm also press packing, no injection.

Yes, I did the calibration thing and followed all directions. As I recall my problem was with the tissue side looking like s**t, I was thinking that it had something to do with possibly the acrylic boiling off monomer and causing the separator to bubble up. The end result was that the tissue side looked like the surface of the moon. As I mentioned, the GC material seemed to perform better. The L 199 is just not designed to be microwaved, IMO.

 

[Flipperlady]

..... the pits could be caused by lots of things. Did you boil out as usual , paint sep let it gloss over and injected while flask was warm?
If so, it sounds like the acylic was brought up to temp too quickly . Maybe divide the 15 minutes into increments. 5 minutes on low, 5 min on 600 watts (medium on mine) then turn over and 5 minutes. I'm not going to buy a special microwave to do this, either it works on what i have or i'll just stick to the naturecryl but the reline doesn't match up with the 199 shade.

 

[kcdt]

199 has a different set of instructions on power settings/times when you microwave it (15 minutes at whatever power setting calibration determined). Hitting a higher temperature could boil away monomer, so that is most likely why you got surface porosity. Technically you can microwave any HC resin, but, as is often the case, if it's not designed for it, the results can be unpredictable.

Personally, I've used Acron MC, then NaturCrylMC since '95. Never a hitch with it. If you want a closer match to 199, try the Light Fibered +.

 

[Jmichael]

My microwave is over 20 years old, it might have contributed to the problem. I have been using ivoclar's Probase auto cure/cold cure material in the "Preference" shade for my reclines recently. The shade match to L199 is not perfect, but even Dentsplys 199 repair material does not match heat cured 199. With the Probase, you can jig it, or flask it for press packing, which is what I do. Note that if you are going to press pack it, it sets up fast. No leisurely 3-4 trial packs. I stick the powder & liquid in the freezer for an hour before using it to slow down the set up time when press packing.
Keep us posted on your L199 microwave trials. IMO, the only way to really match heat cured 199 is to do a press packed & heat cured reline using L199. I would tell them up front that there will be an charge extra for those, and tell them that you have to have them overnight. They can then opt for the more expensive, better matching L199, or the lesser expensive and faster cold cured reline. I have a pretty good idea which one they will want.

 

[Jmichael]

Personally, I've used Acron MC, then NaturCrylMC since '95. Never a hitch with it. If you want a closer match to 199, try the Light Fibered +.

Yes, try the Light Fibered+, it's pretty close.

 

[Flipperlady]

Thanks, besides the reline match I'm also looking at the price. i never buy acrylic in bulk so I'll always have fresh , I buy the 11 unit kits with powder and liquid, pricier in the long run but I like to use it. The price for 199 is about $50, the price for same size naturecryl is about $150. I'm surprised dply would advertise that you can microwave 199 and it would be so hard to get a good result. Anyway, I'll give it and the light fibered a try.

 

[kcdt]

I don't know what your volume is like, but I'd be willing to bet that if you moved up to a 5 lb, powder and a qt liquid, you'd be happier, and it would be more cost effective. It'll take you around 2 qts of monomer to get through the polymer, but you can order those one at a time for freshness.
My2 cents.

I refer to naturcryl.

 

[Anziano]

Patterson dental supply (for example)

Lucitone 199's 11 unit package (231 grams of powder W/ liquid) @ $53.75 = $4.88 per average denture (21 g powder)

Nature-cryl Mc One pound kit (453 grams of powder W/ liquid) @ $95.25 = $4.50 per denture (20-21 g powder)

Someone can correct my math if it's incorrect. it's late at night for me. after writing this i just looked it up also at Nowak and its at $77.29 per 1 pound kit. I had mixed results with my trials with microwaving lucitone. Some were great some were not. For actual patient cases I just used a dedicated microwave acrylic when i made the switch and haven't had issues yet. A 3 minute cure and knowing I'm following set directions by the manufacturer lets me feel confidant about the process.