need help flasking

[tilly]

Aloha,
I'm new to this field and any insight would be great. I'm recently running into more problems when I'm investing partial dentures with Metal fames. when I invest the first half I use yellow stone to cover the teeth and clasps not in wax, creating a hump. once it's completed and removed from the boil out I go to separate the two sides and more time then not the hump that I created breaks off with the plaster and exposes the clasps making finishing more time Consuming because it's covered in acrylic.

Please share your knowledge
thank you,
tillyc

 

[karleames]

make sure that when you cover the clasps and teeth that you taper the stone like a teepee. long and a mild slope to the edge of the flask. and use lots of separator before you pour the 2nd half.

 

[kcdt]

Aloha,
I'm new to this field and any insight would be great. I'm recently running into more problems when I'm investing partial dentures with Metal fames. when I invest the first half I use yellow stone to cover the teeth and clasps not in wax, creating a hump. once it's completed and removed from the boil out I go to separate the two sides and more time then not the hump that I created breaks off with the plaster and exposes the clasps making finishing more time Consuming because it's covered in acrylic.

Please share your knowledge
thank you,
tillyc

You're leaving undercuts.
Take your time with the investing; it pays off in finishing time.
Worst mistake you can make when you're starting out is thinking fast is the same as good.
If you're using slurry or fast set and it's going too quick to let you be both productive and thorough, then move to a slower set.
Actually, if you use a regular set plaster, you can make use of the extra working time to invest more than one (but I ALWAYS emphasize mastering the technique first. Speed comes after, and some things shouldn't be rushed through)
Your best friend is the business end of a #7 plaster knife. It has a completely flat blade that facilitates creating flat slopes with no undercut. You can also lay it against the slope as a plane and check for spaces.
Anything (undercuts, I mean) left after the plaster sets should be blocked out with a judicious flow of wax or petroleum jelly.
Don't forget the separator.

 

[AJEL]

Are you processing partial on a master model? I use a duplicate model with block out built into the duplicate. Depending on tissue undercut I fit processed case on master cast, that way I have best possible going out the door.

 

[kcdt]

Are you processing partial on a master model? I use a duplicate model with block out built into the duplicate. Depending on tissue undercut I fit processed case on master cast, that way I have best possible going out the door.

I'm a huge fan of duplicate models. They allow one to do what's needed to produce without ever harming the master cast.
If you're in a position where you can make that call, that's the way to go.

 

[kytoothdude]

It sounds like you are doing first pour and then covering frame and clasps? should all be incorporated in one body of stone.

 

[tilly]

It sounds like you are doing first pour and then covering frame and clasps? should all be incorporated in one body of stone.

I invest the first half in yellow stone and cover the teeth and clasps. once that's set I invest the second half with plaster

 

[Denturepropgh]

Definitely make sure that there are no undercuts in the 1st half, everything should be smooth, and the more dome-shaped, the better. We vaseline our duplicate models with a thin coat of vaseline before 1st pour (helps when retrieving model post-processing) also, after pouring 1st half, make sure you are letting the stone setup first before using a seperator, and pouring your second half. We use a little tide with water mixed in a container and use a nice sized brush to apply the tide water to the first half before pouring second. The water should feel silky, and it smells nice as well. A lot nicer than a set of nasty dentures that you have to grind on. Who knew that tide could be used for more than washing clothes?!!

 

[OceanwildReinhart]

1, use cheap modelling gypsum you can find in any construction stuff shop(i dont understand why need to buy special plaster, it gives as good results, or just use the special plaster only for second half to cover the wax and teeth, just a tiny bit) 2. If you want to save the cast, apply tinfoil around margins and smear the bottom with dish liquid soap just a bit and let it dry ( this step is optional if you dont have a duplicate and you need the cast),3. Dont forget to grind the occlusal surface of the gypsum teeth otherwise it it wil be retentive and when you separate the flasks it will break. 4. Mix the gypsum, fiirst pour a little bit of it on the clasps and the grinded teeth, next you pour it into the flask and put the cast in it, and create a non retentive surface. After it gets a little bit hardened clean the teeth and the wax with a brush, under water jet and keep finishimg the surface with your fingers under water to get a smooth surface. 5. After is hardened, isolate only the gypsum area (no teeth or wax) with dish washing liquid soap, trust me, its the best isolating stuff out there for gypsum. Let it dry and mount the second half. 6. Mix a more liquid state of gypsum and pour it on the second half under vibrating table if you have, if you dont have just pour little by little so it covers intimately the try in, so it dont make extra bubbles. And youre done. Tips: after you boil the wax off, and prepare for packing, isolate the casts with special liquid not soap duuh [emoji14], the important thing is to aply it in one direction NEVER APLY BACK AND FORTH, ONLY ONE DIRECTION! And im dead serious about it, otherwise you will get the cast with ton of gypsum stuck on it, i did it before back and forth applied 4 times and still got gypsum on it, with one direction applying is enough one time but done good. When its overand you deflaskh clean the thing as much as you can with a spatula and throw dat mofo in the ultrasound bath and leave it for half an hour or more if you have time . You're welcome

 

[AJEL]

The cost of a type 1 or type 2 gypsum diference is not great. Construction gypsum has various fillers and uncontrolled expansion. GMP for consistent results use standardized gypsum.
Dish soap, vasolinr or water glass might do same thing and is up to comfort of technician.
Acrylic separator (tinfoil substitute)(I'm old enough to have done tin foiling) use the best you can. If wax or soap are left on model or flask gypsum there will be problems. All current separators react best a n hot surface.

The hump with undercuts I think Tilly understands, either use duplicate model, 1st half invest without undercut or use sufficient vasoline to prevent breakage.

My best thought out suggestion is to have a notebook, and make notes, when you do something and jot down results, this will speed learning curve.

Welcome to this addicting, artistic field, try to attend conventions to further your learning, pay attention to safety. Wear Mickey Mouse ear muffs at the modrl trimmer, and don't eat at chemical benches. My tips but then I've only been at the bench since 67.

 

[OceanwildReinhart]

I dont know how much costs the gypsum over there but i get it with 80 cents 2 kg's for flasking and preliminary casts, im talking from a perspective on which we need to use cheap stuff to get some profit, over here our lab charge 100 euros for a denture, and this is the most expensive in town, other charge iven 60 euros but they usually do poor dentures. And i get 35% on each denture, thats the fate if you dont own lab, i saw that in US they charge like 500+ $ for a denture, well i guess its not the case to use cheap techniques. And the most annoying thing is that docs want quality, fast, and cheap, F dat.

 

[AJEL]

If construction grade gypsum is used here more likely than not no one will care, but one lawsuit will require purchase records. Non medical grade could contain toxins, FDA is a monster.
I don't know any denture labs getting $500. (maybe Mattix TomZ) I have Bottom feeders around me charging $90. And that includes teeth. Medical grade type 2 costs $30. 20 kilo, plus shipping. Pottery plaster is $20. Per 20 kilo. I'm the only one that will work with me, I watch my waste not many mixed bowls hit the bin. I would rather only stock type 2 & type 3, not much storage for having many different bags of stuff around, and I do over dentures, & implant cases having uncontrolled expansion makes an expensive bar Pretty junk.
Maybe I'm old and just don't want problems with non quality controlled materials, just don't want to be reworking out of my purse or patching because I tried to save a cup of coffee.

 

[CShof]

After you invest the first half you can go back and visually look for any undercuts you missed while smoothing out your investment. When you find them cover those undercuts in wax then invest the top half. After awhile you'll get good at recognizing what needs blocked out with wax.

 

[tilly]

thank you for all of your advice.after taking extensive notes, I think it simply comes down to me not recognizing my undercuts well enough
do any of you have a good video on investing partial dentures that you would find helpful?

 

[tilly]

1, use cheap modelling gypsum you can find in any construction stuff shop(i dont understand why need to buy special plaster, it gives as good results, or just use the special plaster only for second half to cover the wax and teeth, just a tiny bit) 2. If you want to save the cast, apply tinfoil around margins and smear the bottom with dish liquid soap just a bit and let it dry ( this step is optional if you dont have a duplicate and you need the cast),3. Dont forget to grind the occlusal surface of the gypsum teeth otherwise it it wil be retentive and when you separate the flasks it will break. 4. Mix the gypsum, fiirst pour a little bit of it on the clasps and the grinded teeth, next you pour it into the flask and put the cast in it, and create a non retentive surface. After it gets a little bit hardened clean the teeth and the wax with a brush, under water jet and keep finishimg the surface with your fingers under water to get a smooth surface. 5. After is hardened, isolate only the gypsum area (no teeth or wax) with dish washing liquid soap, trust me, its the best isolating stuff out there for gypsum. Let it dry and mount the second half. 6. Mix a more liquid state of gypsum and pour it on the second half under vibrating table if you have, if you dont have just pour little by little so it covers intimately the try in, so it dont make extra bubbles. And youre done. Tips: after you boil the wax off, and prepare for packing, isolate the casts with special liquid not soap duuh [emoji14], the important thing is to aply it in one direction NEVER APLY BACK AND FORTH, ONLY ONE DIRECTION! And im dead serious about it, otherwise you will get the cast with ton of gypsum stuck on it, i did it before back and forth applied 4 times and still got gypsum on it, with one direction applying is enough one time but done good. When its overand you deflaskh clean the thing as much as you can with a spatula and throw dat mofo in the ultrasound bath and leave it for half an hour or more if you have time . You're welcome

thanks for that tip! ill defiantly be paying more attention to that im applying the separator in one direction. I usually don't have a problem with stone sticking, but on the rare occasion I will and im lost as to what I did differently.

 

[pdent]

Aloha,
I'm new to this field and any insight would be great. I'm recently running into more problems when I'm investing partial dentures with Metal fames. when I invest the first half I use yellow stone to cover the teeth and clasps not in wax, creating a hump. once it's completed and removed from the boil out I go to separate the two sides and more time then not the hump that I created breaks off with the plaster and exposes the clasps making finishing more time Consuming because it's covered in acrylic.

Please share your knowledge
thank you,
tillyc

Place a little rope wax around the hump and you will not have any more problems!

 

[budgenator]

I have gotten into the habit of sanding the 1st pour with wet/dry sand paper, I just haven't had any separation problems after doing that. Just a fast buffing with 400 grit under running water does the trick. I also found the if you actually have to sand out an undercut on a 1st pour, the wet/dry nail sanding boards you can get from the beauty supply stores work marvellously.

 

[Timmy]

just remember this
make investment too high or too low, it could be undercut
tilt model appropriate to make minimum undercut when you first half investing.

when you can't handle yellow stone well, hard type putty make you easy.

it's little bit late reply but i hope you read it

 

[tilly]

Place a little rope wax around the hump and you will not have any more problems!

wow! never thought of that, thank you

 

[lcmlabforum]

Not the whole thing, just the 'foothill' area.