Best metal rpd flasking technique for productive retrieval and finishing

[Denturepropgh]

Howdy fellow brainstormers. I was wondering if anybody has some tips for blocking out the guideplanes on cast rpd frameworks and minor connectors/clasp assembly prior to flasking 2nd half.

You see, I began working for a private practice but the doc doesn't want to spend a lot of money on major equipment till next year. In my former laboratory, we had a shell blaster. So although still time consuming, it got the job done. Here, I do not have that luxury and I don't want to bend the framework while divesting.

I was thinking about mixing up some alginate (on the thinner side) and using a thin metal spatula to first block out proximal guideplanes, and quickly place the rpd on the duplicate model, kinda squishing it down and extruding excess alginate. Then I would remove the rpd and clean up saddle areas and seal down the rpd. Next, I'd mix up a bit more and use it for minor connectors, and clasp assemblies. Alginate adheres to dry gypsum, so I don't need to worry about it displacing or sticking to my 2nd half of investing as long as its smooth and well lubed with vaseline. From this point, I'd just invest as usual. I would not have any alginate over the major connector, ensuring that the frame would not displace during trial packing.

Does this seem like a time saving strategy, or a disaster waiting to happen? Last thing I want is a strip and redo. Will alginate shrink during the boil out? Will the properties of the alginate affect polymerization of the acrylic? I need a easy way to divest these on a tight budget.

As always, thank you all very much for your insight and direction. It's a wonderful community we have here!

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[JMN]

Howdy fellow brainstormers. I was wondering if anybody has some tips for blocking out the guideplanes on cast rpd frameworks and minor connectors/clasp assembly prior to flasking 2nd half.

You see, I began working for a private practice but the doc doesn't want to spend a lot of money on major equipment till next year. In my former laboratory, we had a shell blaster. So although still time consuming, it got the job done. Here, I do not have that luxury and I don't want to bend the framework while divesting.

I was thinking about mixing up some alginate (on the thinner side) and using a thin metal spatula to first block out proximal guideplanes, and quickly place the rpd on the duplicate model, kinda squishing it down and extruding excess alginate. Then I would remove the rpd and clean up saddle areas and seal down the rpd. Next, I'd mix up a bit more and use it for minor connectors, and clasp assemblies. Alginate adheres to dry gypsum, so I don't need to worry about it displacing or sticking to my 2nd half of investing as long as its smooth and well lubed with vaseline. From this point, I'd just invest as usual. I would not have any alginate over the major connector, ensuring that the frame would not displace during trial packing.

Does this seem like a time saving strategy, or a disaster waiting to happen? Last thing I want is a strip and redo. Will alginate shrink during the boil out? Will the properties of the alginate affect polymerization of the acrylic? I need a easy way to divest these on a tight budget.

As always, thank you all very much for your insight and direction. It's a wonderful community we have here!

Sent from my SAMSUNG-SM-G920A using Tapatalk

I think that putting something between the model and frame would increase your chances of a problem with the frame bending from support differences.

Anything that does not require acrylic to be processed on or around it should be covered in plaster in a soft undercut-less dome just like the rest. Carefully tapping the plaster over the metal should remove it quite effectively if the metal was polished prior to being investing.

 

[Doris A]

Since the doc doesn't want to spend a lot here's one on eBay, cheap. http://www.ebay.com/itm/CMP-Nobiliu...blaster-Acrylic-Partial-Denture-/252932432646

 

[denturist-student]

Some small dabs of polyether or pvs self mixed might do better than alginate. I use that when I relieve for doing a functional impression or to provide relief for molloplast b liner....I have never tried blocking out the undercuts and have just cut them away from the bottom of the model...The shell blast will work well too.

 

[Denturepropgh]

I have these cases due on Tuesday, that's why I wanted to try to get em done in such a way that they won't be difficult to get off the duplicate model. Maybe I'll just block out the guideplanes with wax and make my dup with the blocked out areas. Though it seems that when you pry them off, its bad juju no matter how careful you are. Do you all use superglue on your major connectors and rests of clasp assemblies when seating on the dup before sealing down? I used to have an issue with rests ending up not totally seating when seating partial to master after processing. I'm thinking they were over-packed, because we would see acrylic flash under the major connector.

Doris, that does look like a very nice machine. I like the fact that it has built in suction. I'm a little leary buying things used, but I'll talk to the doc and see what he says. I live in Pittsburgh, Pa so Macon,GA is a bit of a hike. Thanks for the suggestions.
So you really think that blocking out with alginate will cause the frame to bend under the forces of trial packing? It would only be the slightest of alginate used. The majority would be banked with plaster. I'd like to try it maybe on an old frame or something just to see what happens. I'm an experimentive type of fellow, and sometimes it gets me in a pickle.[emoji51]



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[kimba]

Do you make the frameworks? if you do , after you have duplicated the master model in the refractory material, remove the spacer sheet for the mesh areas. This leaves the wax blotting out on the undercuts which have been surveyed to make the framework. then duplicate this to setup and process on. Guideplanes are already blocked out for you in stone

 

[Denturepropgh]

Nope. Don't make the frames. But that's an excellent nugget of info. Thanks kimba. Is there any faster way of waxing out undercuts on the dental surveyor rather than just adding bit by bit from the wax pot and then using wax carving surveying rod? I just want to see if there is any good info on quickly blocking out, because it sounds like you might have more rpd knowledge than I do. I'm more complete dentures, but I dabble in the other specialties from time to time. It just seems like it takes a while to properly block out a cast.

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[kimba]

I don't know of any other technique , I just use a sheet of boxing wax and a waxknife and add the wax on then cut back with the surveyor tool. You get fairly quick over time , like anything. Maybe ask the lab that does your frameworks not to boil off the master model before they send the castings back.

 

[Denturepropgh]

Good idea. And I didn't think to use boxing wax. That would be waaaay faster than carving baseplate wax. Thank you for the tips!

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[Denture Dude]

Ive been looking for a better way to do this as well. I mean, once the undercuts/ guideplanes are filled with cured acrylic, I don't know of a way to get the partial off without sectioning the model, carefully break it all apart, and then go in with a number 8 round bur and surgically remove all the stone/ clasped teeth one tooth at a time,, sounds like the consensus says the only other way to do is shell blast? Im in sorta the same situation, the 'last guy' didn't need a shell blaster so why do you lol.