Have you ever made...

[aidihra]

... a full zirconia crown? Let's say there's a molar with very little room, but the patient doesn't want a full metal crown, would you or have you made one in zirconia? Also, would you make a zirconia coping with zirconia margins (like a pfm with metal margins)?

I'm just curious.

 

[CatamountRob]

I believe it is not done because zirconia is too abrasive for the opposing teeth. As for the zirconia exposed at the margin, that can probably be done, however without porcelain over it, it would look different than the rest of the tooth. I'm not sure how tissue reacts to zirconia. Rob

 

[Al.]

Glidewell is trying to sell a crn called Bruxzir. It is a full coverage zir crn.

Estheticly it dosnt look to good and I think it may work like sand paper on the opposing like Rob said.

 

[JohnWilson]

Glidewell is trying to sell a crn called Bruxzir. It is a full coverage zir crn.

Estheticly it dosnt look to good and I think it may work like sand paper on the opposing like Rob said.

Actually when ZI is polished properly its less abrasive than traditional glass we layer over our restorations.

I wouldn't be surprised if someone was able to figure a way to do dual shades while infiltrating the colorant on these full contour units to simulate an incisal contrast.

 

[sixonice]

Actually when ZI is polished properly its less abrasive than traditional glass we layer over our restorations.

I'm not sure about that. Zirconia is 1000 Mpa - 1500 Mpa depending on which manufactuer your reading about. Natural human enamel is approximately 90 Mpa. So polished or not, it is the hardness that matters, and something that hard opposing something that soft.......it's no match - the zirconia is going to destroy whatever it opposes except may non precious alloy (or car bumper). Esthetically the stuff is a disaster.
I'm gonna try and dig up some tech specs for everyone.

 

[charles007]

Hardness, flex strength, has nothing to do about wearing down teeth. Opaque is not hard but extremely abrasive. Using diamond paste on a glazed surface is less abrasive than just glazing , there are studies to prove that point !

sixonice enamel is 90 Mpa... I remember a number of 400, what am I remembering ?....I'm almost positive 400 or 450 is the ? of a tooth.
Anyone ??

I have always wondered about the shock from the hardness of zir in the mouth, if that would have any effect in using it on c&b crowns.
my $.02

Charles

 

[SSDS]

Highly polished zirconia has the same abrasiveness of type 1V gold, highly polished zirconia around the margin that has been sterilised, not touched with fingers or alcohol will actually encourage gingival attachment. Coloured lava with porcelain overlay on buccal and palatal and exposed zirconia on the occlusion would look miles better than a full metal crown

 

[JohnWilson]

Highly polished zirconia has the same abrasiveness of type 1V gold, highly polished zirconia around the margin that has been sterilised, not touched with fingers or alcohol will actually encourage gingival attachment. Coloured lava with porcelain overlay on buccal and palatal and exposed zirconia on the occlusion would look miles better than a full metal crown

Funny that you mention this, we have a case with a similar request in the lab now. We do procera in my lab for the majority of all single units unless LAVA is prescribed specifically. We do double scanning of wax ups and merge files. We are waiting for a case to come back that we waxed full contour and cut back the facial only for a 2nd molar. Tight bite, short prep, patient refuses gold so this was the Dr's choice. I think it will work out great.

 

[aidihra]

I was thinking that a zirconia coping with zirconia margins all around would be good for dentists that can't make a proper margin. I've had a dentist (that doesn't know how to trim a proper prep) give me a knife edge preparation and ask for porcelain butt margins. Zirconia margins would be a solution for these type of dentists that don't want metal.

I remember a 4 unit zirconia bridge that was returned from the dentist because the bite was high. He trimmed the porcelain of the last molar down to the zirconia framework in the occlusal distal area. I just polished the zirconia and sent it back. The patient and dentist were happy.

 

[paulg100]

an old thread but see the latest edition of dental poducts report for an update on this.

Good article in there with a real nice result.

Still would like to see some more studies on wear though to convince me.

 

[TheLabGuy]

an old thread but see the latest edition of dental poducts report for an update on this.

Good article in there with a real nice result.

Still would like to see some more studies on wear though to convince me.

For curiosity reasons.........
What is the research saying about the wear with BruxZir?

 

[charles007]

In the next few months you will see a newer Bruxzer type of zirconia that will be more translucent.........

 

[paulg100]

The only info i have come across on wear was comparing monolithic LAVA zirconia to monolithic Lithium Disilicate. The LAVA was said to be only marginally higher.

Sorry i cant remember where it was on the net now, but i dont think the study was by 3m.

Re the translucencies of Zirconia, you should be aware that you can increase the translucency of your zirconia by playing with the sintering temps.
The higher the temp the more translucent the zirconia will be, but at the loss of some strength.

If you are interested then take a look at item 3 on this page for an insight into the effects of sintering temps.

Zirkoniumdioxid

Im guessing this would apply to any zirconia as they are all very similar in their makeup.

Ive been playing around with this brand and sintering at a slightly higher temp and it does not affect the fit.

 

[DMC]

Re the translucencies of Zirconia, you should be aware that you can increase the translucency of your zirconia by playing with the sintering temps.
The higher the temp the more translucent the zirconia will be, but at the loss
Ive been playing around with this brand and sintering at a slightly higher temp and it does not affect the fit.

You mean you still get the same loose fit as usual when using the cerec system? This is a very poor idea, and I'm sure all major manufactures would strongly disagree with you on that.

Are you even able to adjust the shrinkage rate of your material with your Sirona system?

I searched and searched and do not see FDA approval for this generic zirconia for use in the US. Are you in the US?

 

[toof makr]

first of all...ZIRCONIA...is NOT sandpaper...(to the opposing dentition)
polished...it is very kind...if it is GROUND on...and NOT brought back to a glaze...you have PROBLEMS...especially if it's a BUNCH of grinding...best thing is to re-fire...once you take a jack hammer to it...it creates micro-fissures...NOT GOOD...RE-GLAZE...
anyway...Zr CAN BE two tone...hell...3+...the "Lab i use"...is pretty smart...
they have this rocket scientist that really knows his STUFF...they hand paint...instead of dip...the colors...where they want them to be...

and...4wiw..,.glidewell ain't all that...as a matter of fact...one of the worst i've ever...really...think continental and dale are a step above from that...would love to put smith sterling in there...but i already DID...

look...the ole "KISS" principle applies here...and if you're having any trouble...?

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[paulg100]

i hand paint all my zirconia. This gives much better control of subtle colour and allows a thinner layer of ceramic, whilst still acheiving a vital result. This also avoids the strength loss from dipping (around 150mpa from the last study i read). Just sprinkle with ceramic and fire that first before painting, otherwise the stains have a habit of smearing over the smooth zirconia.

No i am am not in the USA im in UK. details for FDA and CE approval can be found on the site along with all the science info re manufacture/sintering etc.

Dental Direkt

I agree with the theory Keltic, just need some data for proof as this is the first thing my clients are gonna ask about.

this is the other worry with monlithic zirconia for me, the dentist adjusts the bite and introduces micro fracture or dosent polish properly. You know how they love to hack our lovely occlusion away.

No you cannot adjust the shrinkage rate accuratly with the sirona system. The shrinkage is controlled by a code for each batch with any 3rd party zirconia. In theory i guess you could adjust the shrinkage with the code but this is not published.

The sloppy fits are because people bump the spacer up to avoid time seating the units. With a little time seating you can set a tighter space and acheive much better fits. Not an ideal situation obviously. I think the bur diameter needs to be larger because of the wet milling.

"This is a very poor idea, and I'm sure all major manufactures would strongly disagree with you on that."
Im not agreeing or disagreeing with it, as i dont know enough about the chemistry of zirconia. These are just my findings and observations.

Have just ordered some Crystal High strength and Super Trans zirconia to play with, so looking forward to getting that.

The new GC Luster Paste kit looks promising for the external staining as the pastes have ceramic paticles.

 

[sirmorty]

A few quick questions for those doing monlithic zirconia crowns.

What type of diamonds/wheels are you using to fine tune the occlusion/ create surface anatomy? also get rid of those pesky swirls from the milling. Everything I have tried seems a little to coarse.

Also what temp. are you firing the glaze? I have tried just polishing with "DVA brightness"
but have also tried glazing with just standard glaze and it seems to be allright although it can have that smear look, depending on the shade.

Sounds like I really need to get them "hand painted" before sintering. to really achieve a more predictable result.

 

[paulg100]

ive just milled my fist fc crown and am now waiting for some zirkon zahn prettau liquids to arrive so i can pre-colour before sintering.

I cant see a very good result being acheived without pre-colouring so thats why im waiting.

As for staining sintered zirconia, as you say the stains smear and ive never acheived a good result this way. Usually when staining colour on zirconia i fire a sprinkle layer of ceramic on first so that there is a better surface to accept the stains.

Obviously this is not viable with a fc crown so the only way i can see this working is with GC luster pastes which are thicker in consistancy and have the ceramic particles in for better 3 dimension.

Saying this the in the recent article in dental products report, they guy was using normal ceramic stains and the result looked ok so...

 

[envisiondental]

I've done some FZ's full contoured zcores.. milled from generic zcore from IMC / Issaqua milling center out of Washington. Usually 2nd molars and are being done in place of FGC's. Shades are definitely tough to get right but after a few I think I've got it.. I use my glaze paste and d.sign ivoclar stains to get the shades.. usually a hint of blue a the incisal.. after that I just mist it with that Solara spray glaze. End result looks like a pfm with no room from a recent lab school graduate... hey but the margins are as good as you'd trim and definitely more aesthetic than an fgc. Probably 15 minutes of labor tops into them.. IMC charges me 99 and I charge 175 so not too bad.