Re: Fit on Zirconia Bridges

[brian1981]

*On 3-unit bridge I'm seeing the interproximal margins opening up as a unit. Individually they fit fine.
*On a 5-unit Lower posterior 3 abutments the middle abutment might not seat all the way unless you adjust the distal margin on molar and mesial margin on bicuspid.
*On 6-unit anterior 3 abutments, individual abutments fit well, but as a unit you need to fit distal walls of 6 & 11 and facial wall of #8. After fitting bridge as a unit, the mesial margins of #'s 6&11 will be open and lingual margin of #8 will be open.
*On 5-unit upper posterior 3 abutments individually again fit well but I will need to fit the middle abutment around margins to get bridge to seat as a unit.

(Abutment- prep tooth whichever you would like to call it)
-Scanning a cut-out model using 3Shape D900 Scanner
-Milling with Roland DWX-50 Milling Unit
-Shenpaz Sintra Furnace with Program Settings according to CAP recommend settings
-Using CAP FZ & CAP QZ Zirconia
-Very thin layer of .8mm sintering beads
-Have found these issues in both with or without milling with support bar to framework

What am I missing?

 

[Marcusthegladiator CDT]

Sometimes just letting bridges sinter resting on beads isn't the way to go. Even small bridges can warp. Try using drop bars on your small bridges. On your large bridges try sintering them while sprued to a bar (or piece of the blank).

 

[CoolHandLuke]

sintering problem. in your sintering do you use supports ? not pegs that you stick crowns on, i mean milled supports that you add in the milling stage? you will need it for at least your 5 unit bridge, your 3 unit not so much, unless its huge or very warped to begin with.'

your 3 unit bridge might not be supported enough in the beads.

 

[Marcusthegladiator CDT]

I cant find any google images of dropbars. It would be difficult to explain well and understand. Maybe someone has something with drop bars laying around they can take a photo of.

 

[CoolHandLuke]

no explanation is needed, just create a sprue pattern on your bridge that will allow the bridge to sinter standing on its sprues. put them on a lingual or pontic, not in an occlusal area.

 

[cadfan]

Mill the same parts in pmma if its ok you have a sinter problem when not your scanner sucks. Sinter problems can be solved with drops up to 5-6 units and bars over 5-6 units deepened on the geometry.Curves and great differences in altitude are difficult to sinter on pearls only therefore the bar ore drops.

 

[Marcusthegladiator CDT]

no explanation is needed, just create a sprue pattern on your bridge that will allow the bridge to sinter standing on its sprues. put them on a lingual or pontic, not in an occlusal area.

Mill the same parts in pmma if its ok you have a sinter problem when not your scanner sucks. Sinter problems can be solved with drops up to 5-6 units and bars over 5-6 units deepened on the geometry.Curves and great differences in altitude are difficult to sinter on pearls only therefore the bar ore drops.

BANG

 

[Tayebdental]

 

[grantoz]

Use a support bar nothing else really works.Like the ones shown earlier ,we do full arches all the time we are surprised if they don't fit.

 

[Sevan P]

This mornings Batch all perfect fitting.

In the Tray.

Now mind you these are straight from the tray onto the model no internal grinding at all.

Bridge one fit.

Bridge two fit.

Bridge with support bar top view

Back view

Angle view

After I just cut it off the support brace no internal grinding.

and the final view

I have been doing it this was for a long time with a good seat rate. Also make sure you always fir the units copings and full crown margins UP! Firing them with the margins down in the beads will lead to distorted margins, when the ZR sinters the beads get caught and force the ZR to morph, also use small beads instead of the larger size one. Also what is the firing time and heat rams on the program your using?

 

[Marcusthegladiator CDT]

This mornings Batch all perfect fitting.

In the Tray.

Now mind you these are straight from the tray onto the model no internal grinding at all.

Bridge one fit.

Bridge two fit.

Bridge with support bar top view

Back view

Angle view

After I just cut it off the support brace no internal grinding.

and the final view

I have been doing it this was for a long time with a good seat rate. Also make sure you always fir the units copings and full crown margins UP! Firing them with the margins down in the beads will lead to distorted margins, when the ZR sinters the beads get caught and force the ZR to morph, also use small beads instead of the larger size one. Also what is the firing time and heat rams on the program your using?

Nice, looks like a lot of fun. I dont get to build that stuff anymore.

 

[Sevan P]

Nice, looks like a lot of fun. I dont get to build that stuff anymore.

You need to sell this stuff to work on it Marcus

 

[Marcusthegladiator CDT]

You need to sell this stuff to work on it Marcus

Ive got an MCXL in house. I wont cut, let alone design anything on inlab as far as large cases go, the quality is bad, compared.
But I had a milling center to myself once. Was SOOO much fun. And our docs dont want FCZ. I made two FCZs last year.

 

[Sevan P]

Ive got an MCXL in house. I wont cut, let alone design anything on inlab as far as large cases go, the quality is bad, compared.
But I had a milling center to myself once. Was SOOO much fun. And our docs dont want FCZ. I made two FCZs last year.

Ouch!

Posted from a Galaxy S4.