the metal frame work change ?

taha

taha

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i have question why the metal frame work in the try in is fit but after building up the porcelain become short from the margen
 
TheLabGuy

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i have question why the metal frame work in the try in is fit but after building up the porcelain become short from the margen

What type of metal?
 
Clear Precision Dental

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Any small, nearly invisible amounts of porcelain getting baked inside the coping?
 
Pronto

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Margin creep. Happened to us with high Pd/Ag alloy and we lost an account over it. Never used it again.
 
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Margin creep. Happened to us with high Pd/Ag alloy and we lost an account over it. Never used it again.
I've never had this happen but what do you mean by "margin creep" what causes that?
 
taha

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It not happened with me but with my friend
He said when the doctor try in the crown and the bridge fit but when try to cementation he found short from the finish line
That mean something happened after porcelain cycle
He use bego wiron 99
It is may some dimension change happened in the metal while the the porcelain cycle ?
 
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Pronto

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I've never had this happen but what do you mean by "margin creep" what causes that?

As the metal is continually fired the margin will bow out or "creep" from it cast postion. Some metals can react like a ribbon when grinded on one side. It will sort of "curl" up like a ribbon when you run a scissor over on side to make it curly. You can test alloys by taking a .3mm thick strip and grinding it on only one side. Lay it on a flat surface after firing it to see it has lifted or curled. Putting porcelain on it will make it curl even more making the margin open or loose the sharp edge.
 
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As the metal is continually fired the margin will bow out or "creep" from it cast postion. Some metals can react like a ribbon when grinded on one side. It will sort of "curl" up like a ribbon when you run a scissor over on side to make it curly. You can test alloys by taking a .3mm thick strip and grinding it on only one side. Lay it on a flat surface after firing it to see it has lifted or curled. Putting porcelain on it will make it curl even more making the margin open or loose the sharp edge.
Thanks for explaining, but when you polish or and do the final check under the microscope before it leaves the lab, would you not noticed that the metal is curled or not seating properly on your die and solid models? I would, and would not let that pass me.
 
JohnWilson

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As the metal is continually fired the margin will bow out or "creep" from it cast postion. Some metals can react like a ribbon when grinded on one side. It will sort of "curl" up like a ribbon when you run a scissor over on side to make it curly. You can test alloys by taking a .3mm thick strip and grinding it on only one side. Lay it on a flat surface after firing it to see it has lifted or curled. Putting porcelain on it will make it curl even more making the margin open or loose the sharp edge.

This is a good explanation,

In simple terms Nobel metal predominately PD based have very little problems with distortion after casting even when finished to the margin less than .3

When you get into PD / Au metals most people look for an alloy that is silver free to eliminate the complication that silver can have on porc. Ag and PT add hardness to alloy that helps with the creeping. Another trick is to slow the cooling rate down from the porc oven to try and control distortion. The higher the gold content the slower we cool our bakes.

There are ways to harden you alloy pre cutting off the spru that I know many Labs use. Perhaps someone can elaborate on this technique if they use it in their lab.

We use 3 main Metal Ceramic alloys in my lab and use exclusively Vita Porc with great results with no creep following the above routines.

ARGELITE 71
ARGEDENT BIO 88
ARGEDENT EURO
 
TheLabGuy

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ARGELITE 71
ARGEDENT BIO 88
ARGEDENT EURO

I use
Argelite PF+
Argedent 80
Argenco-W+ (white full cast)
Argenco-40 HN (gold full cast)
Argenco-20 N (gold full cast)
and Captek

That's all my metals, have no problems at all, very pleased, other than the price of gold........thanks Obama, you dueche bag!!!!!!!
 
TheLabGuy

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I use
Argelite PF+
Argedent 80
Argenco-W+ (white full cast)
Argenco-40 HN (gold full cast)
Argenco-20 N (gold full cast)
and Captek

That's all my metals, have no problems at all, very pleased, other than the price of gold........thanks Obama, you dueche bag!!!!!!!

Hey Al, see, no mention of Non-Precious at all..........lol I don't even have it on my fee schedule. It doesn't exist!!!!!! except on the front and rear of your car as a bumper........lol
 
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Hey Al, see, no mention of Non-Precious at all..........lol I don't even have it on my fee schedule. It doesn't exist!!!!!! except on the front and rear of your car as a bumper........lol
I hate working with NP metal, good thing we only use it for our maryland bridges when DR's request it. One time in the summer we had another lab send their cases to us while they shut down for vacation for a week, and all their PFM crowns were in NP metal YIKES. They wanted them finished up to the opaque stage.
 
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C

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It not happened with me but with my friend
He said when the doctor try in the crown and the bridge fit but when try to cementation he found short from the finish line
That mean something happened after porcelain cycle
He use bego wiron 99
It is may some dimension change happened in the metal while the the porcelain cycle ?

Welcome to all, my first post .........

Taha,
You probably can't answer this, the better question is, "Why did your friend send the case out with open margins!!!!!!!

Generally speaking, you don't see margin creeping with NP alloys......
Having not seen this bridge, I would bet that the margins were thinned out way to much, then the margins were sandblasted off....... Or maybe it is marginal creep....Point being, the lab had to see it, why even finish the case.
Soo much wasted time and money............

Marginal creep is more of a bad fitting crown at the margin, margins change after firing porcelain. More of a tight fit, open margins, (bad fitting crown at the margins)
I no longer use np, but when I used Rex 3 and Tallidums, you don't get marginal creep unlike other precious metals...

John Wilson,
Check with Norbert at Argen on your use of Agelite71, Norbert told me last year that the Zinc in 70+ is a no no. Some labs have problems with Vita and Zinc........ I use vm13 now with argelite 61 with paste opaques with Avante build-up liquid. Wouldn't recommend this to anyone else but I haven't had any problems at all....May change to 75+6 to lower the silver content and for press to metal.......

Charles007
 
JohnWilson

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Welcome to all, my first post .........

Taha,
You probably can't answer this, the better question is, "Why did your friend send the case out with open margins!!!!!!!

Generally speaking, you don't see margin creeping with NP alloys......
Having not seen this bridge, I would bet that the margins were thinned out way to much, then the margins were sandblasted off....... Or maybe it is marginal creep....Point being, the lab had to see it, why even finish the case.
Soo much wasted time and money............

Marginal creep is more of a bad fitting crown at the margin, margins change after firing porcelain. More of a tight fit, open margins, (bad fitting crown at the margins)
I no longer use np, but when I used Rex 3 and Tallidums, you don't get marginal creep unlike other precious metals...

John Wilson,
Check with Norbert at Argen on your use of Agelite71, Norbert told me last year that the Zinc in 70+ is a no no. Some labs have problems with Vita and Zinc........ I use vm13 now with argelite 61 with paste opaques with Avante build-up liquid. Wouldn't recommend this to anyone else but I haven't had any problems at all....May change to 75+6 to lower the silver content and for press to metal.......

Charles007

Interesting I had a longtime rep come in when they were courting me to use their metals, they said nothing negative about using Vita with it. Luckily we have no issues with this metal its rock solid consistent for us.

BTW welcome to the forum
 
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"Check with Norbert at Argen on your use of Agelite71, Norbert told me ..."

Norbert he's still around, I met him years ago when he came to Canada to visit our lab and put on 2 day info session.
 

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