Scaling 3D model to match expanded zirconia

[boboyrobert]

Ok guys...so THEORETICALLY...

Say I have a veneer and I want the margins perfectly flush. This is a zirconia veneer and my milling machine can't mill the margin that close without chipping so I need to put a horizontal border of about 100 microns and angled at 75 degrees with 100 microns thickness as well. But then after I sinter it, I have a marginal thickness that I would have to shave down to get it where I want for the veneer.

I'm just thinking zirconia has a expansion rate that I put in (usually about 1.2360). If I print a model of the veneer prep and also scale it to that exact number, could I use that to flush down the margins in green state before sinter?

 

[JMN]

Ok guys...so THEORETICALLY...

Say I have a veneer and I want the margins perfectly flush. This is a zirconia veneer and my milling machine can't mill the margin that close without chipping so I need to put a horizontal border of about 100 microns and angled at 75 degrees with 100 microns thickness as well. But then after I sinter it, I have a marginal thickness that I would have to shave down to get it where I want for the veneer.

I'm just thinking zirconia has a expansion rate that I put in (usually about 1.2360). If I print a model of the veneer prep and also scale it to that exact number, could I use that to flush down the margins in green state before sinter?

It's a 3 diemsional shrinkage. Every feature in every direction gets expanded. THe tooth woould be 1.2360 as wide, as tall, as thick....

 

[boboyrobert]

Yes exactly. So if I also scale the prep stump by that factor (3 dimensionally) the green state would fit on that...

It's a 3 diemsional shrinkage. Every feature in every direction gets expanded. THe tooth woould be 1.2360 as wide, as tall, as thick....

 

[JMN]

Yes exactly. So if I also scale the prep stump by that factor (3 dimensionally) the green state would fit on that...

Ohhh, gotcha now. I misunderstood completely.

YeS!!!! And that's some seriously inventive thinkin' there. Mister.

 

[boboyrobert]

Well it's nice to know the brain still works . This industry makes me feel dumb sometimes haha

 

[JMN]

Well it's nice to know the brain still works . This industry makes me feel dumb sometimes haha

Me and you both brother.

 

[apostolis159]

I have heard a technician mention that at a seminar about 3d printing. He does it with some jobs with similar requirements to yours.
Unfortunately I don't have more info for you, just confirming that others have thought and done it, so it should work. Maybe it will require some trial and error to get the model/die dimensions right, but it should work.

Keep us posted. Pics too!

 

[Wainwright]

Thats what the original procera alumina crown manufacturing process did... I dug up the old video showing it for y'all : )

 

[CoolHandLuke]

the bigger question here is the fact you are doing zirconia veneers

dat don't make no sense batman

 

[charles007]

Don't mean to sound sarcastic, you have a mill, sintering oven, printer, all the expensive modern digital equipment, why are you playing around trying to mill veneers in zirconia knowing veneers are made in LD or porcelain and bonded in for extra strength. Just curious your reasoning ?

 

[boboyrobert]

Don't mean to sound sarcastic, you have a mill, sintering oven, printer, all the expensive modern digital equipment, why are you playing around trying to mill veneers in zirconia knowing veneers are made in LD or porcelain and bonded in for extra strength. Just curious your reasoning ?

Doctor wanted a zirconia bridge 6-8 and veneer on 9 so I wanted to do it out of zirconia to match. Bonding of zirconia is possible using a primer which ivoclar multi link cementing kit provides. If zirconia is sandblasted good it sticks.

 

[boboyrobert]

Don't mean to sound sarcastic, you have a mill, sintering oven, printer, all the expensive modern digital equipment, why are you playing around trying to mill veneers in zirconia knowing veneers are made in LD or porcelain and bonded in for extra strength. Just curious your reasoning ?

I guess it might be an all around better option to recommend doing it all LD since its three units....just press them

 

[CoolHandLuke]

Thats what the original procera alumina crown manufacturing process did... I dug up the old video showing it for y'all : )

this is so old that everyone in this video is now dead.

 

[Car 54]

Thank goodness "we've come a long way baby".

"Danger Will Robinson, danger".

 

[A. M.]

What's Wrong with zirconia veneers? We did them, and it can look very nice
But I wouldn't adjust the margin before sintering. You just need the right tools and you can do it after

 

[boboyrobert]

What's Wrong with zirconia veneers? We did them, and it can look very nice
But I wouldn't adjust the margin before sintering. You just need the right tools and you can do it after

What do you use?

 

[Affinity]

What primer are you using? I didnt know ivoclar had a zirconia bonder.. monobond or ivoclean are not bonders. The very definition, I think, of bonding being that it infiltrates both mediums being bonded, which is why you etch dentin and emax, to create pits for the material to infiltrate. The closest thing Ive seen is from IDS cad, its actually adds nano particles to the zirconia that fire to the intaglio surface, theoretically..
Still waiting to see any scientific studies on bonding zirconia. Id make an emax and send it along for their file.

 

[FASTFNGR]

Ok guys...so THEORETICALLY...

Say I have a veneer and I want the margins perfectly flush. This is a zirconia veneer and my milling machine can't mill the margin that close without chipping so I need to put a horizontal border of about 100 microns and angled at 75 degrees with 100 microns thickness as well. But then after I sinter it, I have a marginal thickness that I would have to shave down to get it where I want for the veneer.

I'm just thinking zirconia has a expansion rate that I put in (usually about 1.2360). If I print a model of the veneer prep and also scale it to that exact number, could I use that to flush down the margins in green state before sinter?

My opinion before you go that route, check your machine and burrs because a well maintained milling machine should not chip your margin. And if you start there you do not need to go anywhere else. I have done a lots of zirconia veneers and I never have a chip on the margin. Supporting that veneer is very important so it will not vibrate during milling. Use double sprues, always.

 

[boboyrobert]

My opinion before you go that route, check your machine and burrs because a well maintained milling machine should not chip your margin. And if you start there you do not need to go anywhere else. I have done a lots of zirconia veneers and I never have a chip on the margin. Supporting that veneer is very important so it will not vibrate during milling. Use double sprues, always.

Okay I used double screws towards the middle because I've had those thin things break in half. Whats your margin parameters? I've been using nano di burs and nothing has chipped accept this veneer...

 

[2thm8kr]

What primer are you using? I didnt know ivoclar had a zirconia bonder.. monobond or ivoclean are not bonders. The very definition, I think, of bonding being that it infiltrates both mediums being bonded, which is why you etch dentin and emax, to create pits for the material to infiltrate. The closest thing Ive seen is from IDS cad, its actually adds nano particles to the zirconia that fire to the intaglio surface, theoretically..
Still waiting to see any scientific studies on bonding zirconia. Id make an emax and send it along for their file.

Bisco primer

It's been our experience that when this product is used and a zirconia crown or veneer is placed it is permanently bonded.
If the crown or veneer had to be removed for some reason, every molecule had to be ground off because the bond strength.
Using a crown spreader to remove like a traditional crown was useless.