np nickle free alloys

[concern pt]

Hi everyone

I'm researching on my own some issues as a very frustrated porcelain tech some problems we are having at our lab with applying vita vmk porcelain material to NNF np nickel free base copings from Argen company. Anterior Copings no matter what process we do to degas and prep metal continue to fracture after firing porcelain. Our company sends out the arg71 scans and metal company switches to this cheaper NNF material. We finish it and follow the process from there. Now as only a tech I have no inner knowledge of why our company continues to allow this I just would like to know outside of what we have already changed on our end with the degas etc process on Argens standards what else we can try. Is VMK vita material even compadable? I'm a very frustrated porc. tech who takes pride in her work and wants a solution found but hands are tied on the job. So was hoping on finding some possible answers I can take to the boss on a suggestion to change this bases.

 

[Travis]

Moved to metal forum.

Welcome to the site.

 

[kcdt]

Hi everyone

I'm researching on my own some issues as a very frustrated porcelain tech some problems we are having at our lab with applying vita vmk porcelain material to NNF np nickel free base copings from Argen company. Anterior Copings no matter what process we do to degas and prep metal continue to fracture after firing porcelain. Our company sends out the arg71 scans and metal company switches to this cheaper NNF material. We finish it and follow the process from there. Now as only a tech I have no inner knowledge of why our company continues to allow this I just would like to know outside of what we have already changed on our end with the degas etc process on Argens standards what else we can try. Is VMK vita material even compadable? I'm a very frustrated porc. tech who takes pride in her work and wants a solution found but hands are tied on the job. So was hoping on finding some possible answers I can take to the boss on a suggestion to change this bases.

Is the CTE compatible with the ceramic you're using?
If there's a discrepancy n the CTE, what kind of cooling cycles are you using to help compensate?
That's the first place I'd look for persistent fracturing.
Fiddling with degassing is only a solution for issues with bubbling or delamination of opaque from the alloy.

 

[concern pt]

Is the CTE compatible with the ceramic you're using?
If there's a discrepancy n the CTE, what kind of cooling cycles are you using to help compensate?
That's the first place I'd look for persistent fracturing.
Fiddling with degassing is only a solution for issues with bubbling or delamination of opaque from the alloy.

We haven't adjusted our cooling cycles because according to vita where we get our porc. material they are set correctly at 2 mins tho I have learned every oven works differently over the years. So I haven't given that option much consideration. I would think these companies know what they are talking about. But I have learned as well we all build differently and this can be a factor as well. But I think I will try anything at this point. Thank you I will try upping my cool time this coming week.

 

[ICONDENTAL]

Hi everyone

I'm researching on my own some issues as a very frustrated porcelain tech some problems we are having at our lab with applying vita vmk porcelain material to NNF np nickel free base copings from Argen company. Anterior Copings no matter what process we do to degas and prep metal continue to fracture after firing porcelain. Our company sends out the arg71 scans and metal company switches to this cheaper NNF material. We finish it and follow the process from there. Now as only a tech I have no inner knowledge of why our company continues to allow this I just would like to know outside of what we have already changed on our end with the degas etc process on Argens standards what else we can try. Is VMK vita material even compadable? I'm a very frustrated porc. tech who takes pride in her work and wants a solution found but hands are tied on the job. So was hoping on finding some possible answers I can take to the boss on a suggestion to change this bases.

The C.T.E. for VMK Master is 13.8----15.2 @ 600 and the C.T.E. for Noblecrown NF is 14.8@ 600 that makes them comparable, in another view , the suggested procedure for degassing is 650-1010°C,with Vacuum, no hold, remove oxide , if you increment 15 °c on your first opaque "only" will help with your bonding also if you use paste opaque? get a hot plate and and dry your opaque for at least 5 minutes at " low " temp., the rest of normal procedures are calibrate and purge your oven. This are good alloys just needs to stick to procedure , Hope it helps. Happy New Year !!!!

 

[concern pt]

ok thank you everyone for your suggestions. Unfortunately we have tried all these options. We are still having bonding issues, fracturing on anteriors as well as some posteriors now as well. We use a paste to slurry then spray (powder opague) on the shade. We use the method set by metal company from sandblasting to degassing, temp, vac, hotplate etc. I have personally set my oven temp a little lower and set my cooling time to 8 mins which has worked wonderful but while being finished, glazed, polished or steamed and at times even after it has reach the dentist we are still fracturing just the porcelain or all the way to metal indicating a bonding issue. We are even massaging the slurry into metal as you would a captec crown with paste per another lab suggestion. Could the shape or thickness of the metals be an issue? Is there a way to stop the oxide forming at every fire? I'm wondering if this oxide could be the problem dispite r sandblasting before slurrying. It still clearly forms inside the crown even after it has been slurried because it causes a green discoloration after the spray opague has been applied and fired at times around the margin of crown and needs to be touched up.??? We have seen some improvement but not enough even one fracturing is disappointing, wasted time and material.
Thank you
Frustrated Porc. tech.

 

[Al.]

Insane to try to make it work switch metal or porc or both till you find a combo that works for you.
I have 1 fracture and I say ok mabey it was a fluke 2 fractres and I switch metal immediately

 

[dt2013]

did u ever solve your problem and how.......

 

[charles007]

Not familiar with that alloy but the CTE of 14.8 is high for Vita, or either Master's CTE is higher than Omega 900 and VM13
I've used Vita for years with Np, N, and HN, but always used an alloy close to 14.2 range as possible...

I use to use Argens Argelite 61 14.4 to 14.7 with 1 min. cool & 2 min on larger bridges for years with Vita
and no problems, ever.. well over 10 years with several Vita porcelains.( Argens Argelite 61 is cheaper than 71 and offered as DPM)
Noble Crown NF 14.4 -14.8 personally I would never use an alloy with a CTE that high on Vita.......
May want to try 4 to 5 min slow cool on 1 case that's already opaqued as a test crown before dumping that alloy for sure.
Try firing a wash of porcelain over a checked crown and slow cool for 5 minutes to see if the check heals itself,,, and doesn't check
again hours later !
If your coping are poorly designed, lots of thick porcelain, and with a high CTE.... BINGO/ checking
Some labs are firing a Bonder wash on SLM alloys to solve many SLM problems, but checking ?

I agree with Al, one crown checks and you look at the framework design. Second crown checks and you immediately change alloys
and for foolishly making the second crown.... lol
If you want to use NP alloy off scans, or cast inhouse, send scans to Talladium and use Tilite alloy matched to Vita, or cast inhouse with Tilite......
Tilite is NP unlike Noble Crown NF which is Noble........

 

[Drizzt]

Use a bonder coating . Is the metal you get from Argen SLM ? If yes , use a bonder coating , it ''fixes'' CTE .

 

[H.Ross]

I used DeguDent alloy Nickel free and Ivoclar Inline. worked very well for two years but I won't lie, ceramic chipping in patient mouth was noted more than Np with Nickel

 

[Baobabtree]

Use a bonder coating . Is the metal you get from Argen SLM ? If yes , use a bonder coating , it ''fixes'' CTE .

I agree with Drizzit, when I switched to NP 8 yrs ago I had same problems, now I use ceram bond from Bredent(other bonders are available),and have never had a crack since.