Sintering Zirconia Q&A

[ABV]

also keep in mind it also matters how many units you are firing at one time. If you only have 1 or 2 you can get away with sintering it at a faster time.

Brent,
Is Nexxzr Anterior available yet?

 

[alaa22]

The units that were underfired looked like this:

well >> how i can fix this problem ?! i have this problem in Shera blank !!

 

[Brent Harvey]

These restorations look under fired.. Can you tell us the process that was used?

 

[Brent Harvey]

Brent,
Is Nexxzr Anterior available yet?

Sorry for the late response was in India and just got back. We will be having a meeting on confirming the launch dates today. Will reply by end of day with update.

 

[French Cadman]

Salut Brent !

And the new coloring liquids ?
Sagemax Berlin said begining 2016 and you , what do you say ?

 

[Brent Harvey]

Salut Brent !

And the new coloring liquids ?
Sagemax Berlin said begining 2016 and you , what do you say ?

for the USA we will be Releasing our NexxZr Anterior and our NexxZr Coloring liquids by March. For the European market that date has not been set. I would be optimistic and say minimum by June of 2016 for the NexxZr Color, however the NexxZr Anterior its looking positive by march for the European market as well.

 

[elpiojoxp]

Hello, what do you think about my case? its a CubeX2 and it dont look good.... It should be colour A3,5. It dont have stain and glaze, only pre sintering Dental Direkt liquids and sintered. Do you think its over fired or underfired? What I did wrong?

I used this sintering cycle:

Ramp 1: 8° C per minute

High Temp 1: 900° C

Hold: 0 hr 30 min

Ramp 2: 3° C per minute

High Temp 2: 1550° C**

Hold: 2 hr 0 min

Cooling Reg: Cool to 400° C in 2 hours


After the unit was at 400° C I also let it cool in the chamber to 75° C and then I open slowly the chamber. (It have a autolift / autodown platform, like the porcelain furnaces, its has not a door to open).

The furnace its new, only used two times (one for the following cubex2 bridge) have four MoSi2 heating elements (should be new too).

Any help will be very much appreciated! Thank you all

Regards

 

[Getoothachopper]

Hi , I think you are too high with the temp . I find they look the best sintered at 1450c .Thats the first thing I would change .

 

[Brent Harvey]

Hello, what do you think about my case? its a CubeX2 and it dont look good.... It should be colour A3,5. It dont have stain and glaze, only pre sintering Dental Direkt liquids and sintered. Do you think its over fired or underfired? What I did wrong?

I used this sintering cycle:

Ramp 1: 8° C per minute

High Temp 1: 900° C

Hold: 0 hr 30 min

Ramp 2: 3° C per minute

High Temp 2: 1550° C**

Hold: 2 hr 0 min

Cooling Reg: Cool to 400° C in 2 hours


After the unit was at 400° C I also let it cool in the chamber to 75° C and then I open slowly the chamber. (It have a autolift / autodown platform, like the porcelain furnaces, its has not a door to open).

The furnace its new, only used two times (one for the following cubex2 bridge) have four MoSi2 heating elements (should be new too).

Any help will be very much appreciated! Thank you all

Regards

View attachment 21175
View attachment 21171
View attachment 21172 View attachment 21173 View attachment 21174

This definitely looks over fired. Since the Zirconia is a cubic zirconia it needs to be at a much lower temperature. Your firing cycle looks good, just replace the 1550 Deg C hold temp to 1500 Deg C. You should see a major difference.

 

[elpiojoxp]

Ok, thank you very much for your help, I will sinter and hold to 1500°C and I will let you know what happens.

Regards

 

[CoolHandLuke]

i know it says Cubex2 is "cubic" zirconia but i have my doubts. every piece of literature i can read about Cubex2 only calls it cubic zirconia but offers no explanation how exactly it qualifies as cubic zirconia.

Brent can you shed any light on that?

 

[Brent Harvey]

i know it says Cubex2 is "cubic" zirconia but i have my doubts. every piece of literature i can read about Cubex2 only calls it cubic zirconia but offers no explanation how exactly it qualifies as cubic zirconia.

Brent can you shed any light on that?

Yes of course, Because the material is below 800 MPa it is classified as a Type 2 Class 5 medical device which falls under the same category as feldspathic ceramics. when you go into a Type 2 Class 6 ISO standard classification it is required that the material be above 800 MPa in Bi flexural strength. having said that the reason that light passes through cubic zirconia so easily is that the micro-structure is not tightly bonded as the tetrahedral, which is why both materials behave so differently as far as mill-ability, stain-ability, work-ability etc....

Hope this helps let me know if you have further questions.

 

[CoolHandLuke]

so not cubic in the traditional imitation-diamond cubic zirconia definiton then.

because from what i understand in order to create that you need to head it to above 2900 C. i guess that kind of cubic zirconia is different categorically at that point ?

technically if we lab rats had an oven that ran to 3kC could we produce cubic zirconia in that sense ?

 

[BobCDT]

Hi , I think you are too high with the temp . I find they look the best sintered at 1450c .Thats the first thing I would change .

One problem we have found, most sintering furnace temperatures drift higher over time. Thus, 1450 last year could actually be 1550 now. Calibrate every 3-6 months regardless of furnace brand. If you find the temp is off by more than 25 degrees, calabrate more often.

 

[Brent Harvey]

so not cubic in the traditional imitation-diamond cubic zirconia definiton then.

because from what i understand in order to create that you need to head it to above 2900 C. i guess that kind of cubic zirconia is different categorically at that point ?

technically if we lab rats had an oven that ran to 3kC could we produce cubic zirconia in that sense ?

Yes to get to that type of cubic it would need to be processed differently.

 

[BobCDT]

Furnace calibration is very important.

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.

I agree. The Dekema furnace reads and stores specific critical program functions real time. Voltage, spikes or drops become obvious and are readily available for each and every cycle. It also stores actual muffle temps for every firing. It makes for very easy troubleshooting when or if things go astray.
Here is a screenshot of the recorded temperature during a firing cycle in a Dekema. You can see the top temp deviation is about 1 degree over about 100 minutes. This is what's needed for sintering these new gen materials are they are so sensitive to sintering cycles.

 

[elpiojoxp]

Hello everybody, This is me again, I will post two photos, both crows should be A3,5, They are CubeX2, The theet 1.1 was sintered at 1450 C. The theet 2.1 was sintered at 1500 C. Both crowns looks too grey and with a pearly appearance, such as the colour having inside a marine oyster. The sintering same sintering curves for both crowns, the only difference was the high Temp (1450C and 1500C):

Ramp 1: 8° C per minute

High Temp 1: 900° C

Hold: 0 hr 30 min

Ramp 2: 3° C per minute

High Temp 2: 1550° C

Hold: 2 hr 0 min

Cooling Reg: Cool to 400° C in 2 hours and then let cool to room temperature naturally.

Both crowns, have grey effect Dental Direkt liquids in the incistal portion, A4+ in the cervical portion, SA2 in the incisal portion and dipping in A4 for about 1 minute. I let dry for about 2 hours at room temperature.

(Furnace and Heatting elements MoSi2 are brand new)

How can achieve better results? What I need to change?


Thank you very much, regards

 

[thewhitelab]

Hi,

We recently purchased some 'Katana - Super Translucent Multi-layered' Zirconia discs.

After the sintering process was complete we noticed some small white blotches on the product (image shown below).

I was just wondering if anyone might know why this has happened and how we can prevent it in the future?

Many thanks if you are able to help,

~The White Lab
http://thewhitelab.co.uk/

 

[zero_zero]

Whenever I had that issue, replacing the sinter beads fixed it...

 

[Brent Harvey]

Hi,

We recently purchased some 'Katana - Super Translucent Multi-layered' Zirconia discs.

After the sintering process was complete we noticed some small white blotches on the product (image shown below).

View attachment 21501 View attachment 21502

I was just wondering if anyone might know why this has happened and how we can prevent it in the future?

Many thanks if you are able to help,

~The White Lab
http://thewhitelab.co.uk/

Overtime you sintering beads will get contaminated and getting white spots is one of the effects of having bad beads. If firing daily i would recommend that you change out your beads monthly, as you know 1 bad cycle can be costly, so it is well worth it to create a schedule to change out your sintering beads.