Sintering Zirconia Q&A

Brent Harvey

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Hi everyone. I have been seeing allot of questions about sintering on here lately and wanted to create a thread where all of these questions and answers can be in one place, to make it easier for people to search later on. So any questions you have on sintering feel free to post her and DLN will help you out!
 
PearlZ

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well then lets get some discussion going.

has anyone tried sintering via induction ? if so what were the results?

does the Yttria content alter the zirconia's time-to-sinter or high sintering temperature?

what is the fastest you can cool zirconia.
 
Brent Harvey

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i will answer with the question followed by the answer.

Question: Results of Induction Sintering of Zirconia.
Answer: Zirconia is a non conductive material, which is a useful property in the dental industry, as it does not create hot and cold sensations orally. Induction works well for metals and metal alloys as the object itself is heated and not the environment around the object, therefore a material such as zirconia that is non conductive would not heat well. Sintering furnaces therefor on the market are for the most part convection types, very similar to porcelain ovens, as it produces more esthetic results.

Question: Does the Yttria content alter the zirconia's time to sinter or high sintering temperature?
Answer: Yttria is a stabalizer as zirconia by itself is an unstable element. Adding different quantities of Yttria changes the properties of zirconia ie. translucency can be affected by addition of slight amounts of Yttria. That being said the Yttria content does not alter the time to sinter for Tetrahedral types of zirconia.

Question: What is the fastest you can cool zirconia?
Answer: A typical recommended is that you cool 8-10 degrees Celcius per minute to at least 450 degrees Celcius and then a natural cool to room Temperature.

That is my best thoughts on the matter... Feel free to share your thoughts!!
 
BlakeHarting

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Does raising/lowering the sintering temperature change the way zi looks?

If so what happens when fired too low? Too high?
 
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yes and not always the way you would think it would.example over sinter the 600mpa stuff it comes out white milky colour.
 
Brent Harvey

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Does raising/lowering the sintering temperature change the way zi looks?

If so what happens when fired too low? Too high?
Yes it changes the Aesthetics of the zirconia in a big way. it all depends on weather it is high fusing zirconia, low fusing zirconia, cubic zirconia, tetrahedral zirconia or even shaded zirconia. Sintering Hold Temperatures plays a big part of how the final outcome of that product will turn out.

typically if you fire the zirconia at to low of a temperature the color will not be correct and it will be a chalky dead look. If fired to high Depending on how high it will ether turn out milky or raise the translucency of the zirconia. For example: if you fired a crown at 1540DegC and wanted more translucency and bumped it up to 1550DegC you might get more translucency but if you go well over the recommendation of that zirconia it will come out a white milky color as grantoz has mentioned.
 
ts4341

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Brent... Why has SageMax promised a 7 layered zirconia for over a year and yet nothing is available?

You can fast sinter Origin Live Zr 20-25c ramp speed. XT has a 15c ramp speed cycle but i have seen some units fail at this speed.

The new super trans. zirconia needs slower times.
Crowns: 8c up - hold at 900c for 30m - 3c up to (1450c) 2h hold - 4c down to 900c - 8c to 200c
Bridges: 6c up - Hold at 900c for 60m - 3c up to (1450c) 2h hold - 4c down to 900 - 8c to 200c

Different color liquids need different drying techniques also to create correct coloring.
 
BlakeHarting

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Is it possible to "refire" a batch of zirconia that was originally underfired?? To fire it again at a higher temperature?
 
PearlZ

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Is it possible to "refire" a batch of zirconia that was originally underfired?? To fire it again at a higher temperature?
my experience tells me no this is not possible without sacrificing the colour and translucency - while it will work technically, it never looks acceptable.
 
Brent Harvey

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Brent... Why has SageMax promised a 7 layered zirconia for over a year and yet nothing is available?

You can fast sinter Origin Live Zr 20-25c ramp speed. XT has a 15c ramp speed cycle but i have seen some units fail at this speed.

The new super trans. zirconia needs slower times.
Crowns: 8c up - hold at 900c for 30m - 3c up to (1450c) 2h hold - 4c down to 900c - 8c to 200c
Bridges: 6c up - Hold at 900c for 60m - 3c up to (1450c) 2h hold - 4c down to 900 - 8c to 200c

Different color liquids need different drying techniques also to create correct coloring.
we are currently working on a patent for the 7 Layer. This is the reason for not releasing the 7 Layer yet. I have checked on when the patent will be completed but have no time frame as of now.
 
zero_zero

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we are currently working on a patent for the 7 Layer. This is the reason for not releasing the 7 Layer yet. I have checked on when the patent will be completed but have no time frame as of now.

No patent yet, but you've advertised the product already...I find it quite bogus. I read no agreement yet with the patent holder: http://www.google.com/patents/US20130224454
 
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Could anyone answer what i did wrong. I have kerox zirkonia ant mihm vogt ht-s speed sintering furnace. If Im using kerox recomended parameters my restorations usually are too narrow so I started using metoxit parameters and everything is fine. My kerox zirkonia sintering parameter:
s1 10 900 30
s2 5 1450 120
s3 10 900 0
s4 10 150 0
metoxit parameters:
s1 2 300 15
s2 5 1500 60
s3 10 900 0
s4 10 300 0

thanks
 
BlakeHarting

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Could anyone answer what i did wrong. I have kerox zirkonia ant mihm vogt ht-s speed sintering furnace. If Im using kerox recomended parameters my restorations usually are too narrow so I started using metoxit parameters and everything is fine. My kerox zirkonia sintering parameter:
s1 10 900 30
s2 5 1450 120
s3 10 900 0
s4 10 150 0
metoxit parameters:
s1 2 300 15
s2 5 1500 60
s3 10 900 0
s4 10 300 0

Whoa. I just came here to ask a very similar question.

I just got a Mihm Vogt and it was underfiring units. I'm actually working through the problem and so far the solution is to increase high temps 20 degrees. I'm praying this fixes it.

Is it possible that Mihm Vogts fire a little cool? Is it possible that voltage drops may add some unpredictability to sintering ovens?

EDIT- What do you mean by your restorations "are too narrow" when using kerox recommended parameters?
 
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Patrick Coon

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Whoa. I just came here to ask a very similar question.

I just got a Mihm Vogt and it was underfiring units. I'm actually working through the problem and so far the solution is to increase high temps 20 degrees. I'm praying this fixes it.

Is it possible that Mihm Vogts fire a little cool? Is is possible that voltage drops may add some unpredictability to sintering ovens?

EDIT- What do you mean by your restorations "are too narrow" when using kerox recommended parameters?


Furnace calibration is very important to how your restorations fit. In fact they way we calibrate our S1 Furnace is to sinter a zirconia ring and measure it with a micrometer, depending on the amount that it shrinks we increase/decrease the calibration value in the furnace.

Voltage/amperage drops will also effect the way your furnace performs. Any large piece of equipment that draws a lot of power (any furnace) needs to be on it's own circuit in the fuse box. That means one plug/one breaker, and depending on the equipment (burnout, press, sinter) either a 20amp or 30amp circuit. This ensures that you don't have an amperage drop when another piece of equipment on the same circuit cycles on. I have seen this happen with labs that are having sporadic pressing issues all of a sudden. The lab starts to grow and adds more equipment that they plug into the same circuit as their furnace, and all of a sudden they start having short pressings. They then moved the equipment to dedicated circuits and "miraculously" their issues disappear.
 
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Furnace calibration is very important to how your restorations fit. In fact they way we calibrate our S1 Furnace is to sinter a zirconia ring and measure it with a micrometer, depending on the amount that it shrinks we increase/decrease the calibration value in the furnace.

Voltage/amperage drops will also effect the way your furnace performs. Any large piece of equipment that draws a lot of power (any furnace) needs to be on it's own circuit in the fuse box. That means one plug/one breaker, and depending on the equipment (burnout, press, sinter) either a 20amp or 30amp circuit. This ensures that you don't have an amperage drop when another piece of equipment on the same circuit cycles on. I have seen this happen with labs that are having sporadic pressing issues all of a sudden. The lab starts to grow and adds more equipment that they plug into the same circuit as their furnace, and all of a sudden they start having short pressings. They then moved the equipment to dedicated circuits and "miraculously" their issues disappear.
So True. Im now on my 3rd breaker box/ power up grade in the lab. One of the most expensive things you can do is try to save money.:eek::confused:
 
BlakeHarting

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Furnace calibration is very important to how your restorations fit. In fact they way we calibrate our S1 Furnace is to sinter a zirconia ring and measure it with a micrometer, depending on the amount that it shrinks we increase/decrease the calibration value in the furnace.

Voltage/amperage drops will also effect the way your furnace performs. Any large piece of equipment that draws a lot of power (any furnace) needs to be on it's own circuit in the fuse box. That means one plug/one breaker, and depending on the equipment (burnout, press, sinter) either a 20amp or 30amp circuit. This ensures that you don't have an amperage drop when another piece of equipment on the same circuit cycles on. I have seen this happen with labs that are having sporadic pressing issues all of a sudden. The lab starts to grow and adds more equipment that they plug into the same circuit as their furnace, and all of a sudden they start having short pressings. They then moved the equipment to dedicated circuits and "miraculously" their issues disappear.

So True. Im now on my 3rd breaker box/ power up grade in the lab. One of the most expensive things you can do is try to save money.:eek::confused:

All you guys are awesome and I love this site. :p

Why wouldn't a drop in amps cause an error message on the furnace though?
 
CoolHandLuke

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because of how power supplies work. inside are circuits that help maintain a voltage and amperage, and can do that for certain few seconds after power drops but not very long. it will take a surge of current or severe dip to make the power supply unable to cope. thats when units fail.

same as a computer, you want it connected to an Uninterrupted power supply (ups) or battery backup to help stabilize this fluctuation in power.
 
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Whoa. I just came here to ask a very similar question.

I just got a Mihm Vogt and it was underfiring units. I'm actually working through the problem and so far the solution is to increase high temps 20 degrees. I'm praying this fixes it.

Is it possible that Mihm Vogts fire a little cool? Is it possible that voltage drops may add some unpredictability to sintering ovens?

EDIT- What do you mean by your restorations "are too narrow" when using kerox recommended parameters?
I mean my crowns with kerox parameters after sintering are too small, i need to grind a lot from inside to make it fit on the die, afterwards crown margins becomes a bit short. but with metoxit sintering parameters it fits perfectly. maybe I program furnace stages incorrectly.
Can you explain whad do you mean underfiring units. because once I tried a new blanks, and after sintering i got that kind of white spots (photo) that company immediately took my blank for research. Sorry guys for my language barrier
 

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BlakeHarting

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I mean my crowns with kerox parameters after sintering are too small, i need to grind a lot from inside to make it fit on the die, afterwards crown margins becomes a bit short. but with metoxit sintering parameters it fits perfectly. maybe I program furnace stages incorrectly.
Can you explain whad do you mean underfiring units. because once I tried a new blanks, and after sintering i got that kind of white spots (photo) that company immediately took my blank for research. Sorry guys for my language barrier

The units that were underfired looked like this:
79551cc5f20512930fb4f48e9e94a57b.jpg


Really yellowish light and opaque.

That's weird that the contraction was so different on yours though. You didn't notice any discoloration or anything?


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