Polishing acrylic s&p

[trisha]

I am having trouble getting a perfectly smooth acrylicing in the center of most palates that require full coverage. Any suggestions on what product or wheel will help with this problem. I can usually get them pretty smooth but still see some grain lines in the middle that I can't buff out?
Thanks,
trisha

 

[Teofil]

3 pieces of 120 sand paper tape. Like sandwich, two rough sides up, one down.
I cut it like this to make it more flexible. Make sure to "tenderize" it on some old piece of acrylic before use on actual appliances.
You can also use this tool to clean acrylic around the wire parts, it can't damage wire but handles acrylic easily.
I use it when I'm smoothing the edges on clear thermoplastic retainer too.
Give it a try

 

[Inman Labs]

Try felt cones, they come in different sizes and work great.
Regards,
Don

 

[labdude]

Palates will recede with time. Therefore, horse shoe them. Unless you have a dr that wants all that coverage. Long ago, I started using a 3" white stone to shape the posterior portion of all rets., upper and lower.
With that, I use a 1/2" bur to thin the palate. I don't leave any palate thick. Never more than 2 to 3 millimeters. There is a happy medium in there in which you can pumice all appliances the same way. Few exceptions.
That palate that you can't insert a 1/2" bur into. For those I have a 1/2" bur, cone shaped like you use for your handpiece work, just bigger. This will smooth the tightest palate. These palates have to be pumiced in the center first, otherwise you will thin other areas to much and expose wire.
That being said, I use a 4" 28 ply plastic center buff for pumice on everything. Again few exceptions. I use CL 85 pumice, Whip Mix. Medium. This leaves no visible marks and polishes out clean.
Your pumice may be to coarse, or, the shape of your palates may need more horse shoe shape, or a little more bur work so that the buf can cleanly reach all parts of it.
Now it seems to be automatic, I like a nice thin appliance for patient comfort. I start by shaping around the tooth bearing and gingival area with the small cone bur, as you do. Then to the 3" white stone to shape all appliances. Then the 1/2" bur. Then pumice. In the past I used to have to go back and forth between the pumice and the bur to achieve the perfect shape.
So... what I mean is....make sure your buff reaches into the palate, make sure your pumice is not to coarse.
Teofil, no offense intended, the sand paper method is still taught by Great Lakes, but, it is antiquated.
There are faster ways involving less steps.
Just like using vaseline on your hands and mixing and handling acrylic for splints etc. These applinaces can be "salt & peppered" at a far greater speed with an equal quality that both uses less acrylic, and time to do.
Very busy summer...hope it the same for all of you.
Mike.

 

[trisha]

Thanks guys for the suggestions.

I think I will try the sand paper concoction, thanks Teofil. I have always used the sandpaper (but not like a sandwich) and am very happy with the results, but still unable to get that 1/2 of area in middle that needs to have a high shine.


Don, I have tried those and have not had any luck. I still am unable to get into the very center??? I may be going about this wrong.

Mike, I would rather horseshoe the acrylic but this is a new doctor that has been practicing for 3 years now and these are his specifications.
I also use the stone wheel to shape the horseshoe.

I use a 4" 28 ply plastic center buff for pumice on everything

That is also what I use.

Thanks again guys, busy busy
trisha

 

[labdude]

Try and ease the new guy into the different shape. It is possible to cut the applaince so that the rag wheel will reach the tough spots. Takes trial and error practice. If 1 doesn't polish, try to change the shape of it slightly so the rag wheel might reach that tough spot.
Mike.

 

[trisha]

Mike

Try and ease the new guy into the different shape. It is possible to cut the applaince so that the rag wheel will reach the tough spots

Good idea, thanks! I need to take a look at this from an engineering angle.

 

[RetainerDesigner]

Try and ease the new guy into the different shape.

I have done the "oops!" method before with doctors. Both on purpose and not on purpose.
This is where you make one horseshoe shape and when you deliver it tell the doctor "Oops, I just realized that this is horseshoe shape. Sorry old habit. Go ahead and use this one and if you need full coverage for this patient I will make it free of charge." THis happened to me a couple of months ago . I have 2 doctors that use upper wraps almost exclusively. But one likes the loops over the 3's and the other like the loops over the 4s. I was always worried about mixing them up, one day I did and made the wrap with the loops over the 4's for the other doctor. I caught it too late and went ahead and delivered it. Told him the same thing if he didnt like I t I would replace it for free.
Well he liked it better and now I make all my wraps with the loops over the 4's a lot easier to keep up with, for us slow techs!

I am like Mike I use an acrylic wheel to shape the palette to accept the rag wheel. If the acrylic wheel cant get in the palate I know the rag wheel wont.

 

[labdude]

So now I remember.....
I use a 1" muslin buff, just like the big rag wheel. Stuff it one the end of your tapered mandrel at the pumice station. I do this to pumice the inside areas of a Bionator, and use it once in a while for those "torpedo head" cases.
Exactly Cade.
Also Trisha, like you said, engineer it in reverse. In the past I found out exactly what bur, or sandpaper goody, or what have you, made the grooves or lines to start with.
In doing that, mostly finding what what device made the darn mark to start with, I have completely eliminated the use of sandpaper goodies and the use of a cone shaped white stone as well.
The cone shaped stone would smooth out things prior to pumice work, making the pumice work faster and cleaner.
Then I discovered ( a long time ago, everything seems to be a long time ago for me, actually,it is) that adding to pumice that has been used is not good. Your putting good pumice into pumice that has acrylic etc in it.
That brings me up to what I do today. I like the volume of 3 cups of pumice. And the mix of that amount with 3 cups of water. I'll do 90 appliances with it, then toss it. Makes for quick and well done work pumicing, and elimainated the need for the white cone shaped stone. I like the pumice I use as it is sharp enough to work quickly, and not leave any lines in the acrylic.

 

[trisha]

Thanks guys!

trisha