Fitting acrylic partials back onto model

[sizzur82]

Hello all, i have been lurking around for a while and find the information on this forum quite informative. Thank you all for contributing and letting folks like me learn!

I want to ask how you all go about fitting your acrylic partial dentures back onto the model. In the past, I just went straight to insertion and found it very cumbersome to trim and adjust using the patients mouth.
I have since started duplicating my models. My alginate states that i can double pour my impressions with little distortion and have been doing so thus far. For the most part its okay, but I know there is a slight distortion or less detail captured when pouring out twice with the same impression. It is difficult to make it still due to path of insertion issues or undercuts. I'm using an articulating ribbon to mark any pre-mature contacts.

Another question i would like to ask is how you all flask acrylic partials? All stone/plaster or do you use lab putty around the abutments? I use all stone/plaster but i find a lot of the time they break off during boil out, especially when the abutment tooth that is clasped is surrounded with adjacent denture teeth, and it's always worrisome putting it back together.

Clearly, I am not very experienced yet, but would love to learn new and more efficient techniques.

 

[kcdt]

Hello all, i have been lurking around for a while and find the information on this forum quite informative. Thank you all for contributing and letting folks like me learn!

I want to ask how you all go about fitting your acrylic partial dentures back onto the model. In the past, I just went straight to insertion and found it very cumbersome to trim and adjust using the patients mouth.
I have since started duplicating my models. My alginate states that i can double pour my impressions with little distortion and have been doing so thus far. For the most part its okay, but I know there is a slight distortion or less detail captured when pouring out twice with the same impression. It is difficult to make it still due to path of insertion issues or undercuts. I'm using an articulating ribbon to mark any pre-mature contacts.

Another question i would like to ask is how you all flask acrylic partials? All stone/plaster or do you use lab putty around the abutments? I use all stone/plaster but i find a lot of the time they break off during boil out, especially when the abutment tooth that is clasped is surrounded with adjacent denture teeth, and it's always worrisome putting it back together.

Clearly, I am not very experienced yet, but would love to learn new and more efficient techniques.

Depends on your budget.
Dupe your master model. Don't bother trying to repour alginate- as you've already discovered, it doesn't work.
I recommend using silicone or hydro colloid to dupe the master cast. If you're on a budget, and can't spring for a hydro colloid machine, you can melt it in the microwave.
I prefer silicone, as it has the best ease of use, technique insensitivity, and high degree of accuracy.
I'll get back later about the flaskingl issue; its late.

 

[sizzur82]

Thanks for the reply kcdt! Yes, i'm definitely on a tight budget and unfortunately, cannot afford a machine at the moment. I never heard of melting hydrocolloid in a microwave so there's a neat idea.

 

[kcdt]

Thanks for the reply kcdt! Yes, i'm definitely on a tight budget and unfortunately, cannot afford a machine at the moment. I never heard of melting hydrocolloid in a microwave so there's a neat idea.

You can if you go slow, however, the hydro colloid doesn't last as long as with a machine.
Personally, you can get silicone down to 5 bucks a dupe if you add in previously used, then chopped up molds as filler.

On to your flaskingl issue. Make certain you don't have undercuts. Use wax or Vaseline to block out whatever the plaster knife missed/can't reach.
On those single abutment problems, half flask as usual. Then before second pour putty the area leaving wings so it will get picked up in the second half.
Or, you can flow a thin layer of wax just over the slope so it releases easily. The downside is you are left with flashing to cut away.

 

[sizzur82]

Kcdt, Thanks so much for the help! If by chance, you have the spare time next time you flask such a case, i would truly be grateful to see some pictures as examples? Only if time permitting/you remember/you feel like it, of course

 

[kcdt]

Where I'm currently, I don't flask much unless one of the guys there is gone.
But I'll see if I can get some shots on my phone that will illustrate.
BTA, there's another thread going on here about flasking.
Here's the link: http://dentallabnetwork.com/forums/threads/need-help-flasking.19970/#post-176612

 

[sizzur82]

Thanks again kcdt, sorry for asking such a redundant question, i didn't notice that thread
was definitely a good read!

 

[kcdt]

Thanks again kcdt, sorry for asking such a redundant question, i didn't notice that thread
was definitely a good read!

There are no bad questions. Don't be sorry for wanting to learn more; it's admirable.

There are tons of conversations here in archive. Search forums for topics and you'll find some really great stuff.
It's a real goldmine.

 

[Doris A]

If you don't have any hydrocolloid you can soak your master model for a few minutes and then take an alginate impression of it instead of trying to do two pours.

 

[kcdt]

Thanks for the reply kcdt! Yes, i'm definitely on a tight budget and unfortunately, cannot afford a machine at the moment. I never heard of melting hydrocolloid in a microwave so there's a neat idea.

http://begousa.com/media/WirogelM_instructions.pdf

There's microwave instructions if you scroll down down a little.
Remember to chuck it and start fresh every 10- 14 melts.

 

[sizzur82]

Doris A and Kcdt,

thank you again for taking the time to offer your advice!

Thanks for providing me that pdf link kcdt, appreciate you going out of your way for this!

 

[Doris A]

Doris A and Kcdt,

thank you again for taking the time to offer your advice!

Thanks for providing me that pdf link kcdt, appreciate you going out of your way for this!

That's what this forum is all about...helping each other!

 

[JTG]

Another way to go vs microwaving is a kettle cooker (looks like a fry daddy). They're $20-30 at wal-mart and then you can watch the temp with a meat thermometer. Just make sure you stir frequently, I stir once every 4 mins and the hydrocolloid is melted in 12-16 mins, then I turn it off and its ready in 10 and won't melt my block-out wax.

 

[Chalky]

A technique that I use is to block out your master model with stone... all work (including processing) is done on the master cast, and given all of the undercuts are taken care of there won't be much of an issue with insertion. One of my mentors didn't always trust the accuracy of a duplicate, (although he is happy with the results from silicone... just need to be aware of shore hardness and expansion rates of the stone being used) We'd also block out all our splint models with stone too. Works well when you have an eye for what you are doing.