How often do you get rocking bridges?

[Brett Hansen CDT]

I am trying to help our waxer to decrease the number of bridges we have to cut and solder. I know that scanning and printing them would eliminate this problem, but I don't want to go that route. What percentage of the bridges you wax by hand and then cast end up rocking and have to be soldered? I would say we are around 50%, which is not very good. Here is the technique I am having her use:

-after the bridge is waxed, it is transferred to the solid model
-the bridge is then split between a pontic and one of the abutments
-sprues are attached to the bridge and bar resevoir is attached to the bridge.
-the pontic is reattached to the abutment

I appreciate any input I get.

 

[2thm8kr]

I Sprue with bee's wax one sprue at a time and let cool before moving on to the next.
Allowing each sprue to cool keeps the wax from pulling the bridge frame in different
directions during spruing. I only solder 1-2 out of 100 bridges.

 

[DMC]

I have used wooden tooth-picks as base to wax to in the past...

The best method I had was to use Plastic tubes smashed into oval shapes, then super-glue to abutments!

VERY rigid and no warping.

Also, reduce the space of gap for final assembly to reduce any shrinkage if you are trying to use only wax.

Add very little heat, and close the gap only a little bit at a time....wait for cooling...then add a wee-bit more wax.....wait.....then again.

The smaller you add and the less heat you can get away with will greatly reduce any unwanted shrinking.

I had nearly 100% success waxing big bridges.

 

[lcmlabforum]

Scott,
For someone that much into CAD-CAM - you are still a technician at heart, huh?
I did not know cyanoacrylate would latch on to wax copings?
LCM

 

[DMC]

I can still rock it old-school!

 

[ps2thtec]

Transferring your wax tosolid model seems unnecessary and part of the problem.

Finish sealing the margins on working model, but before attaching your final abutment is connected, put sprues on
and I attach the sprue bar to the Pontic and let cool a moment.
I then connect the remaining sprues and abutment by flowing a zapit material with a thin blade. Spray accellerator and everything sets up at the same time. You can final touch up those areas with a soft box wax if needed.
It's foolproof.

 

[2thm8kr]

I can still rock it old-school!

How's this for Old School?

 

[SiKBOY]

When is she sealing the margins?

 

[CatamountRob]

This is the most idiot proof method I know of, which makes it perfect for me. I learned it from an Ivoclar casting seminar I went to a long time ago.

Wax the abutments and pontic and separate them, check the margins and put them back on the solid model. Then use dental floss to strap down the abutments, use sticky wax to hold the floss to the model. Make sure the floss is pulling straight down. Then reconnect the sections with whatever you like. I use Kerr former wax.


Then add sprues and attach it to a bar.


Let it cool for a few minutes, unhook the floss, carefully lift it off and gently re-check the margins. Then you can put it in a ring base and add single units to the rest of the bar.

 

[rkm rdt]

I thought pfms were dead?

 

[CatamountRob]

I thought pfms were dead?

Not in Vermont. Takes a while for news to get here.

I'm expecting my PFM business to take a hit in July, after the mountain passes thaw, the mud dries out and the riders can get through. Just last month I got my most recent copy of Dental Lab Products, interesting article about some new material called "Dicor"? Looks promising.

 

[Brett Hansen CDT]

Thanks for the pics Rob! I think we are gonna start with using viscous super glue to reattach the pontic to the abutment and see if that works. If not, then I like your technique Rob.

 

[stt672]

Sometimes it isn't always in the spruing of the bridge that causes the rock, in my cases it is hardly ever the cause. If I get rocks it was usually done in the pulling of the bridge from the model. Check to see, maybe he is spruing textbook maybe it is the retrieval of the bridge off the model.

 

[JohnWilson]

How's this for Old School?

View attachment 3899

I have that exact swedge and die kit. Have you ever used it ?

 

[rkm rdt]

Not in Vermont. Takes a while for news to get here.

I'm expecting my PFM business to take a hit in July, after the mountain passes thaw, the mud dries out and the riders can get through. Just last month I got my most recent copy of Dental Lab Products, interesting article about some new material called "Dicor"? Looks promising.

I just read your post.
It takes a while to get the internet up here.
My Ipad is an etch a scetch and every time the dam sled dogs hit a rut all my data gets wiped out.

I hear vulcanite may just be a fad.

 

[disturbed]

The joint
Are you adding the tissue side first?

When adding wax to your connection add wax from the "bottom"up.
99%

 

[CatamountRob]

I just read your post.
It takes a while to get the internet up here.
My Ipad is an etch a scetch and every time the dam sled dogs hit a rut all my data gets wiped out.

I hear vulcanite may just be a fad.

What's an IPad?

 

[REJ]

Back when I was a legit waxer/finisher I used to use a bar of pmma across the top of all the units as a sprue bar. Then lute them together after they settled, not long. Used bordeaux thowax. My claim was my stuff didn't need soldering, and did this routinely with 8 unit and attachment stuff. Key in my opinion was to lock in with rigid material, used to melt all sprue leads then attach the pmma rod, let cool then attache all the sliced units with the bordeaux. Had great result at a picky lab under 20x scopes and almost no solders. Also developed a 2 phase invest for large bridges.

 

[2thm8kr]

I have that exact swedgel and die kit. Have you ever used it ?

Are you kidding? It says right on the label Precision Dental Shell Machine,
I use it for making grills.

On a serious note, I've played with it a few times and can't really see where
precision fits in to the description.
I have a older tech friend that uses something similar for foil veneers
and they have better margins than any other foil veneers I have seen.

 

[DMC]

Many good ideas and techniques here!

I do not to transfer to a solid model either.

Also I attach a bar to frame while on the model as well.

Good Luck! May the Force be with you!