Broken Zirconium bridge

[Drizzt]

Hello everybody ,

Last week came into the lab a case of a five unit bridge from 34 to 38 of a patient , and the dentist asked for a zirconium bridge with no layering . So I designed the bridge , sent it to the milling center and it was made with wieland translucent zirconium . When the doc had the bridge and put it to the patients mouth with the cement , he instructed the patient to bite , using a piece o cotton between the bridge and the antagonist teeth . And then the bridge broke into 2 pieces . Any idea why that happened? I have small experience with the CAD CAM stuff , i have my scanner like a month . The same doc 2 weeks ago broke an e.max crown of a premollar the same way . Any ideas? Thanks .

 

[paulg100]

well for starters with glass (emax, empress etc) ceramics you NEVER EVER start messing with the occlusion until after the crown has been cemented, Otherwise you run a very high risk of fracturing the crown.

As for this cotton technique, again why shove a huge interference between the occlusion and teel the patient to bite on it? of course its likely to break, again espcially if it hasnt been cemented.

I hope you are not re-making these cases for free? doc dosent have a clue what his doing by the sound of it??

 

[DMC]

We have done Hundreds of Bruxzir bridges with Zero failures so far.

??

It does work. No adjusting with carbide, only fine diamond, then rubber wheel if really necessary.

 

[Drizzt]

The doc admitted that he was to blame for the faillure of the bridge . OMG that's a new one ! A doc that actually blames himself !!!

 

[lcmlabforum]

34-38 if FDI system for US numbering of #21-18 if you can confirm whethr that is
a long span without a pier abutment? What was the dimension on the connectors?
Do you know if a disk was used to finish the connector area in anyway?
If things keep breaking in the same clinic, you wonder if the handling and shipping
has been compromised - these are zirconia afterall. Soi many reasons without
looking at the prep, fit vs. impression, etc.
LCM

 

[Mark Jackson]

the dentist asked for a zirconium bridge with no layering . So I designed the bridge , sent it to the milling center and it was made with wieland translucent zirconium

Some zirconias were never intended to be milled in full contour, and the crystalline structure forms irratically during sintering of massive pontic areas. Also, proper post sintering handling has to be adhered to. If the lab uses the wrong tools to refine or adjust the material before sintering (such as seperating interproximal spaces with a disk) you introduce stress fractures that grow and perpetuate during sintering cycles.

It is a precise science, and the lab should be well acquainted with the process.

 

[lcmlabforum]

Thanks, Mark.
question here then - what do you feel to be the strongest
framework material - can you use Bruxir for that purpose and stack
to it since you are so confident with the modification you have made
to stain the material?
Do you have any experience with the pink LAVA custom abutments?
LCM

 

[DMC]

Buccal cutback works well in the posterior. Like a Metal Occlusal PFM.

Same for Anteriors. You would want full lingual in Zirconia. The Bruxzir material is not as strong as most Zirconia, but I believe it is 2x stronger than eMax. Kinda in the middle.

So, the extra material is needed for the bridges (connector areas of course) when choosing the Bruxzir brand Zirconia. The benifit is much better cosmetics vs/ PFM or other Zirconia and the ability to work with tight occlusal spaces. eMax bridges are now obsolete IMO. Too fragile.

 

[NicelyMKV]

I had a framework once that literally came apart at the pontic. I assumed there was the start of a fracture etc in the green state that just expanded and finally separated after a firing cycle.

 

[Drizzt]

The bridge didn't break at the pontic .I would upload photos if only I knew how!