Acrylic.....

[Bumfrey]

So I'm about to start the last stage of my prosthetic course and i have noticed an issue with returning patients. Twice now a patient has come back with ulcers, and upon checking the bite is out. I find the old models to do a check bite and remount to grind in the bite, however the upper denture does not fit the model anymore. It's too tight.
My thought is that i have used too much monomer making the original base plate, and on the second process its effected the acrylic. I arrived at this conclusion because originally i mixed the acrylic like i did by eye many years ago so its like wet sand. Packed in the dough stage yarda yarda....Then i read the instructions ( yer i know) and when i mixed to those instructions IT WAS VERY DRY. Paladon 65. VERY DRY.. Not wet sand. Base plates came out rally nice, so i am a little unsettled.
Any input is welcome.

 

[JMN]

That sure sounds like a logical conclusion, but I've never used that acrylic, so...

 

[Bumfrey]

yeah i was hoping another paladon 65 user reads it and offers any experience.

 

[pdent]

My advice is to check the bite on the articulator when you break the case out. If the bite is accurate at that point, then the original bite was missed. When you get the pt. in the chair, take a blue mousse bite, then remount the case and do your occlusal adjustments.

 

[JKraver]

If you can get a denture to go back perfectly on any cast after it is removed, you are a better man than any denture tech to have ever lived. Dentures simply do not return to processing position after being removed. It is probably not monomer especially after curing. If you think it is process a small flat piece of acrylic and tape it to the patients arm for a day, if they have a rash they are allergic at residual monomer levels. Most likely they are not. ^Pdent's post should solve you problem.

Probase hot is like that feels to thick, so I add a touch more monomer add 15 minutes to the boil process never had an issue.

 

[lcmlabforum]

I routinely make a remake a remount cast using Putty and paperclip for dentures after processing.
If there is any undercut at all, to break the denture out without destroying the stone
will be unlikely, and even if the stone was intact, there will always be some polymerisation
shrinkage to make the fitting of the processed denture on the cast unlikely, and if it does,
you are probably distorting or abrading the denture.
LCM

 

[Bumfrey]

Thanks for all your thoughts guys.
Always remount jobs after processing, and grid the bite in. Its never as was before processing, but its very close.
Always check the bites at issue and they were good to go, always do a check-bite (blue mouse) and remount before patients are given dentures. The problem is that a few months down the track two have come back and the full upper does not fit the model it once did. Its a 'little' too tight.
To be honest Kraver as long as there is no or little undercut they do indeed fit the cast fairly darn perfectly, as i don't break them. They should too. If they didn't they wouldn't fit.

 

[JKraver]

Thanks for all your thoughts guys.
Always remount jobs after processing, and grid the bite in. Its never as was before processing, but its very close.
Always check the bites at issue and they were good to go, always do a check-bite (blue mouse) and remount before patients are given dentures. The problem is that a few months down the track two have come back and the full upper does not fit the model it once did. Its a 'little' too tight.
To be honest Kraver as long as there is no or little undercut they do indeed fit the cast fairly darn perfectly, as i don't break them. They should too. If they didn't they wouldn't fit.

Soft tissue displaces a hard cast does not. Dentures are made to be fit into small undercuts for retention. Acrylic shrinks minutely while and after processing. If the dentures were left dry they could warp as well.

 

[kcdt]

Thanks for all your thoughts guys.
Always remount jobs after processing, and grid the bite in. Its never as was before processing, but its very close.
Always check the bites at issue and they were good to go, always do a check-bite (blue mouse) and remount before patients are given dentures. The problem is that a few months down the track two have come back and the full upper does not fit the model it once did. Its a 'little' too tight.
To be honest Kraver as long as there is no or little undercut they do indeed fit the cast fairly darn perfectly, as i don't break them. They should too. If they didn't they wouldn't fit.

You should be making a putty cast for remounts. Otherwise you're chasing your tail.
Just because they fit the stone cast sometimes doesn't mean they always fit every time.
For remounts, they need to fit every time.
Go with putty.

 

[kcdt]

So I'm about to start the last stage of my prosthetic course and i have noticed an issue with returning patients. Twice now a patient has come back with ulcers, and upon checking the bite is out. I find the old models to do a check bite and remount to grind in the bite, however the upper denture does not fit the model anymore. It's too tight.
My thought is that i have used too much monomer making the original base plate, and on the second process its effected the acrylic. I arrived at this conclusion because originally i mixed the acrylic like i did by eye many years ago so its like wet sand. Packed in the dough stage yarda yarda....Then i read the instructions ( yer i know) and when i mixed to those instructions IT WAS VERY DRY. Paladon 65. VERY DRY.. Not wet sand. Base plates came out rally nice, so i am a little unsettled.
Any input is welcome.

How do they fit the mouth?

 

[Bumfrey]

Soft tissue displaces a hard cast does not. Dentures are made to be fit into small undercuts for retention. Acrylic shrinks minutely while and after processing. If the dentures were left dry they could warp as well.

Yes and i took the impression using medium body and light body for mucocompressive and mucostatic were needed. Small undercuts can rub and cause pain placing in and taking out the denture. All undercuts should be smoothed out no? Dentures could have been left out, i didn't ask them, thanks for that.

You should be making a putty cast for remounts. Otherwise you're chasing your tail.
Just because they fit the stone cast sometimes doesn't mean they always fit every time.
For remounts, they need to fit every time.
Go with putty.

Another guy uses putty for remounts, and i have started to so thanks for backing up that plan. I like it so far.

How do they fit the mouth?

Very well. Many patients comment on how well they fit. The two guys that came back though did say they had become a bit tight, so i eased the undercut areas.

I wasn't really after so much instruction about the process, i was more after experience with paladon 65.
Very helfull though guys.

 

[Bumfrey]

Thanks for all your thoughts guys.
Always remount jobs after processing, and grid the bite in. Its never as was before processing, but its very close.
Always check the bites at issue and they were good to go, always do a check-bite (blue mouse) and remount before patients are given dentures. The problem is that a few months down the track two have come back and the full upper does not fit the model it once did. Its a 'little' too tight.
To be honest Kraver as long as there is no or little undercut they do indeed fit the cast fairly darn perfectly, as i don't break them. They should too. If they didn't they wouldn't fit.

Which bit Tina P??

 

[JKraver]

Stone also cures more over time. Full set is two days on most stones.

It is rare that you can use old models to put dentures back on correctly. Try compression packing a denture thickness of acrylic on a palate and take a 3in disc and cut down the midline. In many cases there will be a .1mm gap that is from polymerization.

Most sore spots are occlusion or poky thing from surface imperfection, run your fingers carefully over the internal surface zip with a small fine/extra fine bur. You can close your eyes it will help focus on tactile sensations. If its not pokey its probably occlusion. Not all undercuts are a problem, and some are beneficial. Its all about insertion angle if they can rotate it in or angle it in the undercut is a benefit in retention. If they get the sore spot near/over a undercut that could be the issue that could be smoothed away/down.

 

[JKraver]

Also what stone do you use? A higher expansion stone could be an issue.

 

[Bumfrey]

Its off topic. The fits of the dentures is great, to start with. A couple have come back later slightly tight. It must be the acrylic mix so i'm working on it.
Thanks for your input though very kind.

 

[denturist-student]

Press packing is becoming a lost art....Better off to spend a few sheckles and get an ivobase or ivocap system....I used to make the facebow mounts and then remount casts...But I am preferring to do that if and when it is needed...I am starting to favor a Turbyfill protcol where the registration and bite are done using a lower bite rim and upper lingualized occlusion....along with a functional impression using Tempo, Hydrocast, or some other form of tissue conditioner....Whatever protocol I choose I always use a solid baseplate usually light cured.....I have noticed a lot of photos here use those small brass articulators.....bad idea....creates a totally different occlusal scheme and one prone to problems....Even with an average mount is far batter than those small articulators that don't represent anything resembling the tmj.....anyways take care and keep well.....have a merry christmas....

 

[denturist-student]

I routinely make a remake a remount cast using Putty and paperclip for dentures after processing.
If there is any undercut at all, to break the denture out without destroying the stone
will be unlikely, and even if the stone was intact, there will always be some polymerisation
shrinkage to make the fitting of the processed denture on the cast unlikely, and if it does,
you are probably distorting or abrading the denture.
LCM

I have seen those who make remount casts dispense with the putty...They fill the deep parts of the intaglio with wet tissue paper and then just make a cast....YOu really only need the vestibular periphery to capture a remount cast....give it a try and save some putty for repairs.

 

[KTR]

If you can get a denture to go back perfectly on any cast after it is removed, you are a better man than any denture tech to have ever lived. Dentures simply do not return to processing position after being removed. It is probably not monomer especially after curing. If you think it is process a small flat piece of acrylic and tape it to the patients arm for a day, if they have a rash they are allergic at residual monomer levels. Most likely they are not. ^Pdent's post should solve you problem.

Probase hot is like that feels to thick, so I add a touch more monomer add 15 minutes to the boil process never had an issue.

I would have to agree, it is rare to put a denture on another model from a different impression after processing.

 

[Bumfrey]

Never said that. Of course it wouldn't fit. Might get close, but rare to get it to fit.
Dentures originally fit the original model after processing very well. Whats the point if they don't.
After a few weeks in the mouth they did not.
Only a couple of cases have been like this, the rest are fine.
Starting to think it was the patient leaving them out to dry as they were sore......

 

[JKraver]

Never said that. Of course it wouldn't fit. Might get close, but rare to get it to fit.
Dentures originally fit the original model after processing very well. Whats the point if they don't.
After a few weeks in the mouth they did not.
Only a couple of cases have been like this, the rest are fine.
Starting to think it was the patient leaving them out to dry as they were sore......

As a general rule, pt compliance is 99% of head scratching never seen before problems.