Problem milling zirc custom abutments

[charyou tree]

Hello,

I don't know how many folks here use the Kavo milling machine, but I'm having a problem milling zirconia custom abutments.

The small pin breaks while milling out the hole in the abutment. This has happened twice in a row now.

Has this happened to anyone else?

Thanks.

 

[Labwa]

The bur?
the hole gets milled on the first cycle before imbedding right?
ive never seen one break on the first side mill. ive had splitting or the zirconia come apart from the wax but no tools break on the reverse after imbedding.

 

[Mark Jackson]

The small pin breaks while milling out the hole in the abutment. This has happened twice in a row now.
Thanks.

Things to check:

1) What zirconia are you using? Is it approved for this use? It may not be engineered for thin wall milling.

2) Is it only happening with a particular implant system? You push may have to stop offering that kind of abutment.

3) Check your milling algorithm. One of the geeks here can tell you better than I can, but I know our machine shift gears several times will milling abutments. The turbine speeds, tools paths and torque adjust for cutting certain geometries. If the turbine is just free wheeling the whole time, it may not be the proper cutting characteristic for that area of the abutment.

 

[k2 Ceramic Studio]

Never had or herd of that before, we do a good number of them and the only bad thing that can happen is the wax snapping during the second side but you Just need to put an old pin in and you are fine, are you double scanning or using the neoss software. PM me for lots of great tricks.

 

[Labwa]

yeah we had toothpick that we would stick down while we heated the zirconia up then poured the wax into the mill side.

 

[disturbed]

Let me try to help you all to understand something. by providing and promoting full contour zirconia crowns we are doing a disservice to patients. Think about it like this: take a rock grinder, place a few opal stones in it, tumble, they simply get shined more; now though in a diamond, in a few hundred cycles you will have nothing but dust, and a slightly smoothed diamond...The same thing will happen in the mouth with full contour zirconia: contacts will open after tooth gnathalogical processes (tooth movement from attrition) opposing teeth will wear often changing function and slowly one tooth can destroy the entire mouth. NEXT... we are all trying to layer to zirconium, zirconium has NO chemical bond only mechanical retention, it can't... ever.. zirconium has no oxidation to bond to. slight wetting of surface is not an adequate bonding layer..E'max is doing the best with there bonder layer for layering zirconium, as it is designed to fire at a higher temp, but, as I have personally seen, even some of the best labs in the country are foregoing it "cuz its a pain to use". The silly idea to just turn up your oven temp for a "bonder" layer is stupidity.. learn your materials! More lucite crystals form when you over cook your porcelain, lucite crystals are weak and the more you have the more likely you will have breakage in the future.It takes a while sometimes but wear is a long process, just because it leaves the lab does not mean its ok later.... thats why we try to cool our pressings guys..to PREVENT over growth of lucite crystals that form. Doctors are seeing chipping more and more..get off the zirconium band wagon and come back to reality. zircon grows with advertising but can die with knowledge..

 

[DMC]

I demand you change your avatar.

That's my woman!

(Zirconia will never work...)

 

[Slipstream]

full contour zirconia crowns <snip>opposing teeth will wear often changing function and slowly one tooth can destroy the entire mouth.

Not according to the studies seen - properly polished Zr does less damage to the natural teeth than the original teeth would have done, not to mention less than any porcelain build

NEXT... we are all trying to layer to zirconium, zirconium has NO chemical bond only mechanical retention, it can't... ever.. zirconium has no oxidation to bond to...

Don't think anyone has ever claimed it does have a chemical bond - mechanical retention seems to work just fine in many industrial processes - heck I see guys lifting paving stone with just suction

Doctors are seeing chipping more and more..get off the zirconium band wagon and come back to reality. zircon grows with advertising but can die with knowledge..

Ahh the good old days - PFM's that did not chip - no one got black margins and metals were not toxic.

OK everyone back to making gold restorations please

 

[BobCDT]

I think it's important to look at the literature. Here is a short & partial list of ware studies that conclude full contour zirconai waers opposing dentition less than feldspathic porcelain.

Schmitt J, Wichmann M, Holst S, Reich S. Restoring Severely Compromised Anterior Teeth with Zirconia
Crowns and Feather-Edged Margin Preparations: A 3-Year Follow-up of a Prospective Clinical Trial. Int J
Prosthodont 2010;23:107–109
2 Crisp RJ, Burke FJT. -Year Evaluation of zirconia-based bridges in general practice: year-three results,
J Dent Res 88(Spec Iss A):3234, 2009
3 Oh W, DeLong R, Anusavice K, Factors affecting enamel and ceramic wear: A literature review. The Journal
of Prosthetic Dentistry 2002;87:451–459
4 Kelly R, Denry I., Stabilized zirconia as a structural ceramic: An overview. Dental Materials 2008;24:
289–298 and references therein
5 Lughi V, Sergo V, Low temperature degradation -aging- of zirconia: A critical review of the relevant aspects
in dentistry. Dental Materials 2010;26:807–820 and references therein
6 J.A. SORENSEN1, E.A. SULTAN2, and P.N. SORENSEN1. Three-Body Wear of Enamel Against Full Crown
Ceramic. J Dent Res 90 (Spec Iss A): #150703, 2011
7 J. GEIS-GERSTORFER, and C. SCHILLE. Influence of Surface Treatment on Wear of Solid Zirconia (LAVA),
J Dent Res 90 (Spec Iss A): #145873, 2011
8 J. GEIS-GERSTORFER, C. SCHILLE. Investigations on Two-body Wear of Dental Ceramics with ABREX .
J Dent Res 88 (Spec Iss A): #29723, 2009
9 R.W Wassell,J.E McCabe, and A.WG. Walls. A Two-body Frictional Wear Test. JDentRes 73(9):1546–53,
September, 1994
10 T. KURETZKY, M. URBAN, R. DITTMANN, R. PEEZ, and E. MECHER. Wear Behaviour
11. A study on the in-vitro wear of the natural tooth
structure by opposing zirconia or dental porcelain
Yu-Seok Jung1, DDS, MSD, Jae-Whang Lee1,2, DDS, PhD, Yeon-Jo Choi3, DDS, MSD,
Jin-Soo Ahn4, DDS, PhD, Sang-Wan Shin1,2, DDS, PhD, Jung-Bo Huh1,2*, DDS, MSD

 

[disturbed]

yes, less than feldspathic porcelain, thats why I choose a flouralapatite porcelain, it is softer than natural dentition and won't harm the surrounding natural teeth, the same with E'max. I personally saw a single central made from feldspathic porcelain destroy someones lower centrals in 5 years..zirconium is MUCH harder than natural dentition.. it WILL wear it away, not so hard to understand right?!? It does not wear as fast as feldspathic because the surface tension, It is much smoother and does not have the pores that porcelain does, these pores act like sandpaper, zirconium is simply a finer grit.. When laying/prressing to it, without a chemical bond the forces of attrition WILL weaken the SHELL baked onto it and when it fractures (eventually it will) it will come off in a BIG chunk.. this is happening for MANY dentists around the country right now.. call a few and ask them if they have any 5 year zirconium breaking. I have, and I was bothered by what I heard form dentists across the country. so now they think full zirc is the answer because its indestructable. it is.. natural dentition is not.. anyone who doubts this, go cut a zirc in half, than cut a feldspathic crown in half, than cut a natural tooth in half.. enough said?? I hope you understand now. and yes some were claiming chemical bond.. some geniuses in the 3m team (lava) even said there might be atomization at chicago midwinter. so they recomended turning up your temps by 100 or so degrees to get a better bond to zirc.. THERE IS NO BOND!! and refer to upper rant to learn about over firing porcelain...black margins come from exposed opaque lines at the tissue level.. tissue HATES opaque.. but thats another day...HAIL THE FGC!

 

[Slipstream]

[YOUTUBE]TLEo7H9tqSM[/YOUTUBE]

Think I'll wait till the movie comes out - Scott he's all yours

 

[rkm rdt]

I've never had any problems with pfz chipping but it's only been about 10 years since I started using it.

 

[Slipstream]

Wonder if it's the way he does them - we have been making up to 200 units a day for 7 / 8 years and our warranty sheet has maybe 1 claim a week for pfz failure.

New technology - it will never catch on, like I told Wilbur and Orville, wasting your time boys.

 

[rkm rdt]

Apparently it's happenning to many dentists across the country...not my country mind you! How about yours Colin?

 

[Mark Jackson]

Let me try to help you all to understand something. by providing and promoting full contour zirconia crowns we are doing a disservice to patients.

You should definately NOT do it then. Definately stay out of that arena, and avoid reading the literature. It's probably all propaganda anyway.

 

[araucaria]

Thanks for cheering me up everybody, this beats reading CE stuff

 

[disturbed]

time will tell...

laughing at been doing it for 10 years.. and at 200 a day and 1 a week fail...100's a week and you think you know whats going on??. why do production labs only see $$$ and not how clients come and go...IF you get a decent design to protect from sheer on your Z copings they will last a while longer. my main concern here is full contour as it is destructive and has NO BOND when layering! time will tell.. and here in the US the higher end dentists are noticing breakage. the lower end that send to you production labs lose clients as soon as there crown breaks so they don't ever see it on things they have done, and most of them won't admit to there own failures..seriously guys.. call around. talk to some of your better accounts and ask them if they are seeing it.. not only in what they are doing but in general..You will hear monolithic a lot because they have realized that two materials are not bonding to each other and they are getting breakage.. it's fairly recent as it takes a while for the fatigue to set in.. I have read the literature, been to the sales meeting, heard the bull****. now watch..time will tell..
PLEASE prove me wrong! prove its not abrasive to natural dentition, prove there is a bond to the coping. when did mechanical retention become enough? I am NOT and never want to be a production tech..I have not done 1000's of z crowns, nor will I because I know my material science...please get off the zirc bandwagon before the PATIENTS get hurt. You big guys that are doing soo many crowns will not see this as your cash blinders are on.

 

[disturbed]

mark.. you are well known in this area..sadly, not for what you might think...right up there with glidewell buddy!! yea!! $$$!!
Collin.. yea new technology...targis, belleglass, eris, eris 2,...shall I continue?

 

[rkm rdt]

I've been doing it for 10 years,where did I say I was a production lab?

 

[TheLabGuy]

I've been doing it for 10 years,where did I say I was a production lab?

Yeah, we know Canadians and production can't be in the same sentence, get with the program already...HA!!!