Spaces Underneath Metal Porcelain

[Essam Abdulaziz]

During the fabrication of porcelain-fused-to-metal (PFM) restorations using Ivoclar IPS Inline ceramic on a metal framework with a matching coefficient of thermal expansion (CTE), surface cracks and subsurface voids were observed specifically in the interproximal connector areas immediately after the first dentin firing, despite following the manufacturer’s recommended firing program.
The metal was prepared by sandblasting with aluminum oxide (Al₂O₃) particles (110–125 μm), followed by an oxidation (degassing) cycle, then application of two layers of opaque ceramic with proper drying between layers.
What are the possible scientific causes for these defects occurring during the first firing in the interproximal areas? And what adjustments in framework design, metal preparation, ceramic condensation, or firing protocol could be recommended to prevent this issue?

 

[kimba]

photos please

 

[kimba]

sounds like porcelain shrinkage but please post some photos

 

[doug]

How long do you pre-dry before insertion into the furnace?

 

[desertfox384]

yes post pictures.
Make a slice all the way to the connector after applying porcelain, this allows the porcelain to shrink towards the bulk without tearing around the interproximals.

 

[Car 54]

I used to fire a foundation bake on all my PFM's, including the bridges. I would build a more chromatic ging porcelain into the bridge interproximals and linguals. That helped to keep from any tearing interproximally during the main build up and firing. Also, building the pontics tissue side up to the lower ging area. I used a couple of other tricks on this foundation build bake that helped with the end results. (one hint, use margin porcelain 1 part with your OD porc. 2 parts for the pontic tissue to help keep it from shrinking due to the margin porcelains higher fusing temp during subsequent bakes)

 

[ztech]

Shrinkage.

 

[doug]

The water was cold!!!

 

[Essam Abdulaziz]

sounds like porcelain shrinkage but please post some photos

ok i'll post photos as soon as possible

 

[Essam Abdulaziz]

How long do you pre-dry before insertion into the furnace?

i just pre dry the porcelain with the time pre drying program of the bake about 90sec before starting the baking.

 

[Tayebdental]

i just pre dry the porcelain with the time pre drying program of the bake about 90sec before starting the baking.

Increase your drying time to five minutes. It depends on how big the case is, and slice with a sharp knife the inter-proximals ceramic buildup area through to the opaque, in this case after baking you have a very clear separation and then you could fill it up with more ceramic in your subsequent second or third bake.

 

[ps2thtec]

I call this a bloomin’ onion. Had some of these back 2018 with inLine. Switched from IVO liquid to some vita RS fluid I had and all good.
Don’t have to deal with that anymore
Remember how much fun this used to be?

 

[grantoz]

i keep forgetting vmks are the best ask any pros