CRACKING!

[thewhitelab]

Hello,

I have just started using cad cam and I am experiencing a problem with my NP bridges usually after glazing, i am hand polishing and cracks are appearing around the pontics? i dont think it is the support as i am using the anatomical cutback software? Has anybody else experienced this? Did you find a remedy if so? i have always used precious alloy and never experienced this problem?

Thanks in advance for any input!

 

[TheLabGuy]

Sounds like your porcelain is cooling before your metal........add some cool time.
Or....a CTE issue between your porcelain and metal...........double check this.
Or....it's car bumper metal and should be left on a car bumper not in the mouth......LOL okay, I had to throw that in there, I don't use NP in my lab

 

[thewhitelab]

cheers, ordinarily i would not use NP myself, unfortunately i'm trying to make my 3shape pay for itself! only to find its probably costing me time/money. kind of wish i stuck to outsourcing?
i would be interested to hear what prep work is taken before the ceramic added?

 

[sixonice]

it sounds like a CTE issue to me. find out the CTE of the NP alloy your using, then check your porcelain's CTE range and I would bet they are either right at the border of CTE compatibility or just out of range. you probably can get your single units through, but once you get into larger masses of NP - especially the pontics as you said, that is where the CTE issues really come to life.

 

[Travis]

What does 3shape have to do with base metal? Is it doing the waxing for you? Iam not familiar with this stuff.

 

[charles007]

Your porcelain doesn't match your NP....3shape has nothing to do with it......
If you have already started on more cases with that alloy, double your cooling time, and change alloys..... If your using a fast cool, change to a 1 or 2 minute cool. Tallidum sells many different NP's to match just about any porcelain on the market.

 

[thewhitelab]

The reason why i mention 3shape is i am scanning and having the substructures laser sintered in germany, currently NP is their only choice of material