Zr sintering teqniques

[nik1618kin]

Trying to avoid unexpected curving of zirconia bridges during sintering. What's the best way to achieve it?
1. Use of a bar connecting the bridge and sinter the whole construction or
2. Put the milled bridge on a layer of sintering pearls into a special ceramic cup and then sinter?

 

[JayH]

If you don't start with a material that's been processed consistently it probably will only be luck that get's you a perfect fitting bridge over 6 units or so. High quality material from a high quality manufacturer.

Isn't 8 units still the maximum size for a lava bridge? And 3M is a materials company! Pressing and pre-sintering that stuff in such a way as to maintain a consistent lattice over large areas isn't easy. If it was, I would think that they would have introduced a full arch solution.

 

[k2 Ceramic Studio]

What size of bridge are we talking about and are you able to mill on a disk and can you place occlusal pins, If you can mill on a disk then try to keep the middle section of the disk connected to the bridge(keep the last two units free) and place incisal pins across the arch to stop it distorting. Hope this helps Pete.

K2 Ceramic Studio's Photos - Two Neoss bridges after sintering and fitted down. | Facebook

Sorry you cant see the pins but hope the pic helps

 

[Swatch8x]

First of all, I agree, you should double check the quality of the Zirconium. It makes a huge difference. I've been using Zirconium from Metoxit and WhitePeaks. Metoxit is from Switzerland, WhitePeaks is from Germany.

Metoxit is my first choice, the deformations can be controlled if you know how to place the attachments in the CAM software and I have produced log spam bridges up to 16 units, I will look for the photos and post them on a later post.

The second tip is to keep the inside of the bridge attached to it during the sintering. I like to use as many attachments on the inside of the bridge as possible.

The third and most important tip: after cutting the bridge out of the disk and coloring it i place it in the furnace standing up. I mean i place it with the incisors facing up and the molars facing the base of the furnace. Imagine sintering a disk and positioning it standing up, not flat on the base of the furnace.

I also tried the sintering pins, but I still got deformations. If i position it standing up in the furnace I don't allow the material to move too much, because it could only try to go down due to gravity, but this is prevented by the material on the lingual side of the bridge.

This way I got the best results

 

[nik1618kin]

I'd like to ask some details about using this "place it with the incisors facing up and the molars facing the base of the furnace" technique. Do you connect the bridge with a bar and put the bar touching the base of the furnace?

 

[Swatch8x]

I leave the whole zirconium chunk inside the bridge, maybe mill 3 or 4 crowns inside just to minimize waste, but I am careful to leave the chunk uninterrupted between the molars on the two semi-arches, I'm not sure that's the right way to say it. And yes, once i detach the bridge from the rest of the disk, i place it standing up inside the furnace, with the chunk of zirconium inside the bridge touching the base of the furnace. I will send you some pictures if it helps, just give a PM with your e-mail.

 

[Mark Jackson]

It's all about the quality of the blank. We mill full arch, zirconia implant bridges with no distortion at all, and no special process other than laying it on a bed of YZ beads. We only use name brand materials.

 

[Swatch8x]

I agree, the quality of the materials is a major factor, but until now I didn't hear of any type brand of Zirconium that doesn't distort at all. I know colleagues that mill using Zirconium from Pretau, Girrbach, etc., and each of them get distortion if they don't compensate by leaving the bridge linked to a piece of zirconium for bigger bridges or leaving the inside of the bridge there while sintering. I am using Metoxit, and I am very pleased with it.
On the other hand, it is normal that you get some distortion if you consider that this material shrinks up to 25%, and every high temperature soak will have this effect on most materials.

But once you get used to this technique it doesn't seem so special anymore. I also use the YZ beads to sinter the smaller bridges, up to 6-7 units after I detach them completely from the disk and I get no distortion at all.

But for bigger bridges and full bridges I would recommend this technique, at least this works for me. I guess it also depends on the furnace.

 

[nik1618kin]

Recommendation of high quality zirconia materials would be very useful.

 

[Swatch8x]

I recommend Metoxit, it is from Switzerland, it is translucent if you have a good furnace, the top sintering temperature is 1500 *C. They are very prompt and quick to dispatch the disks.

 

[Vazone]

no distortion at all, and no special process other than laying it on a bed of YZ beads.

so you even not use standing up pins ? just beads fo 6-7 unit bridge ?

 

[DMC]

Look at those cute little sprues on the inner radius.

0.6mm balls. How big are your balls?

 

[DMC]

YTZ - Yttrium Stabilized Grinding Media


[YOUTUBE]EOB6P-5dJQA[/YOUTUBE]

 

[Richiedo86]

Hi, i want to ask what temperature you use for full arch implant zirconia ???

 

[Contraluz]

Hi, i want to ask what temperature you use for full arch implant zirconia ???

I'd follow the manufacturer's indications! Temperature and sintering times vary greatly between the different types of zirconia. For example, Argen's ST+ sintering cycle is much shorter than Argen's HT+!

 

[Contraluz]

Look at those cute little sprues on the inner radius.

0.6mm balls. How big are your balls?

View attachment 9477

View attachment 9478
View attachment 9477 View attachment 9478

Now these pictures are a blast from the past! Who is still doing full coverage zirconia bridges???

 

[Brett Hansen CDT]

Now these pictures are a blast from the past! Who is still doing full coverage zirconia bridges???

I wouldn't even do a full arch PFM anymore....fixing one we did initially 12 years ago now with monolithic zirc.