8 Venners Over Discolored Teeth

[pingvin]

May I ask, what is the minimum thickness for pressing for emax (for veneers, to be layered ceramic on it)

 

[amadent]

May I ask, what is the minimum thickness for pressing for emax (for veneers, to be layered ceramic on it)

in the emax book ( green cover) on page 16 they recommend a minimum framework thickness of 0.5 mm for veneers- but your final restoration can only be a total of 1 mm in overall thickness

 

[paulg100]

the minimum is until your wax distorts!

I pressed a six unit trial veneer case at 0.09 (YES 0.09) to see how far i could push the system. (thats 0.09 pressed, not after thinning out with a bur!)

They all pressed and fit fine, and you could layer ceramic on these no problem, just keep the ratios of frame to layering thickness in mind.

The lithium disilicate its self does not become unstable or anything like that at these thickness's so its prefectly fine. And you can still handle and work with it fine. Not like feldspathic which would break just by picking it up at 0.09.

The only limit appears to be how thin you can get your wax before it distorts, so just go for it.

Just remember you have virtually no masking abaility at these Ultra thin amounts, so its application is limited.

 

[pingvin]

Thanks guys! So the ratio emax to layered-on porcelain should be 1:1 maximum or distortion will appear? I don't have many veneers, but sometimes doctor would only cut from buccal side up to the contact point and I would have a hell time doing this on refractory as it is almost impossible to separate them, but this way (modeling with wax and pressing) seems very nice approach. What kind of ceramic can you lay on then? I guess EX3 would not fit?

 

[paulg100]

the official ratio is more like 70-80% frame to 20-30% layer ceramic i think.

Im regularly doing 50/50 on .3+ frames with no problem though.

Its not so much a distortion issue, but you will get craking in the frame if you pile loads of ceramic on top. This applies to all the pressables, not just emax.

With ultra thins you might need to be a bit more careful.

And emax ceram is the only ceramic, unless you wanna R&D yourself, but rather you than me

Emax ceram is a lovely ceramic,works on all zirconia fine to.

 

[disturbed]

the minimum is until your wax distorts!

I pressed a six unit trial veneer case at 0.09 (YES 0.09) to see how far i could push the system. (thats 0.09 pressed, not after thinning out with a bur!)

They all pressed and fit fine, and you could layer ceramic on these no problem, just keep the ratios of frame to layering thickness in mind.

The lithium disilicate its self does not become unstable or anything like that at these thickness's so its prefectly fine. And you can still handle and work with it fine. Not like feldspathic which would break just by picking it up at 0.09.

The only limit appears to be how thin you can get your wax before it distorts, so just go for it.

Just remember you have virtually no masking abaility at these Ultra thin amounts, so its application is limited.

I have a different opinion. I have been told by Ivoclar and many techs over the years that we should always follow the manufactures recommendations and by not doing so risk failure. It may go out the door fine but having copings that thin can cause fatigue failures down the line, especially if cemented.

This was 4 years ago.. maybe they changed their minds??lol
Please correct me if I was misinformed By the Ivoclar technical advisor.

 

[rkm rdt]

Paul is talking about veneers here not copings.Big difference

 

[paulg100]

yes veneers NOT crown copings!

sorry if that wasn't clear.

"should always follow the manufactures recommendations and by not doing so risk failure. It may go out the door fine but having copings that thin can cause fatigue failures down the line, especially if cemented."

bond and occlusion are whats gonna cause a veneer to fail, not how thick or strong the material is.

unless you pile a disproportionate amount of ceramic on top, then the shrinkage is gonna cause stress on the frame.

Just keep with in the ratios and i don't see any relevance to the thickness.

100% success with my emax work that Ive done with my brother so far...ZERO failures. and thats allot of large multi unit makeover cases etc.

We've had some failures with other clients but preps have been suspect, occlusion has been suspect, and i have no idea what there bonding protocols are (and neither do they probably!)

"especially if cemented"
If the client wants to cement, tell them to use zirconia!

we know the strength of glass increases a huge amount when dentine bonded (LS2 is what..3.5x),anyone ignoring this is just corner cutting. Dont come and expect a free remake when i told you to dentine bond!

 

[disturbed]

yes veneers NOT crown copings!

sorry if that wasn't clear.

yes, I thought you meant layering on, my apologies.

just curious paul, why does it say
"minimum thickness for IPS cutback tech. 0.4"
and
"minimum thickness for press and stain tech 0.3-0.6"
for anteriors in the
E MAX MANUAL
Failure to observe the stipulated framework design criteria and minimum thicknesses may result in clinical failures, such as
cracks, delamination and fracture of the restoration.
The following minimum thicknesses have to be observed to match the tooth colour of the shade guide and to fulfil the
requirements of the preparation guidelines:
Overall Thickness of the
Restoration in mm 0.8 1.0 1.2 1.5 1.8 2.0 2.5 3.0
Minimum Framework Thickness
of IPS e.max Press in mm 0.4 0.5 0.6 0.8 1.0 1.1 1.3 1.6
Minimum Layer Thickness of
the Veneer with IPS e.max 0.4 0.5 0.6 0.7 0.8 0.9 1.2 1.4
Ceram in mm
For the cut-back and layering techniques, the relationship of the layer thickness between IPS e.max Press (framework) and IPS e.max
Ceram (veneer) must also be observed:


Table
Tops
Thin
Veneers
Veneers Inlays Onlays Partial
Crowns
Anterior
Tooth
Posterior
tooth
Anterior
Region
Premolar
Region
1.0
1.0
–
–
–
–
–
–
–
–
–
–
–
–
0.7
0.4
–
–
–
–
1.0
isthmus width
1.0
fissure area
–
–
–
–
–
–
1.0
isthmus width
1.0
fissure area
–
–
–
–
–
–
1.5
1.5
1.5
0.8
–
–
–
–
1.2
1.5
1.2
0.4
0.6
0.6
–
1.5
1.5
1.5
0.8
0.8
0.8
–
1.2
1.5
1.2
0.8
0.8
0.8
16mm2
1.5
1.5
1.5
0.8
0.8
0.8
16mm2
Minimum
Thickness
IPS e.max Press
Staining
Technique
Minimum Thickness
IPS e.max Press
Cut-Back Technique
(after reduction)
Minimum Thickness
IPS e.max Press
Layering Technique

 

[paulg100]

thanks for quoting the manual, read it many times.

have also taken the official emax course and also sat the course at IDEA with Oliver Brix. And also read many books and articles and see the great options and possibilities that available with this material, that are not in the manual.

may result in clinical failures, may not. Ivoclar are covering them selves for obvious reasons.

Failure of the dentist to bond correctly and manage occlusion MAY lead to clinical failures!

If you wanna play it safe or have clients that have no proper bonding protocol or dont have a clue about occlusion, or cant prep properly, then YES follow the manual.

for anterior resto's we are acheiving 100% succsess with much thinner volumes so far.

Posteriors are a different matter. even then, Kois has proven through TRUE independent study at his own R&D lab with his own material scientist, that bonded fc emax will function and last at 1mm occlusual thickness.

We are comfortable with that.

"The following minimum thicknesses have to be observed to match the tooth colour of the shade guide"

Dont have any problems matching shades (well no more than with any other material!). much of the time im matching teeth, not shade tabs.

we also have anterior cantilevers going strong with large connector. Case selection and occlusual management is the key, although i wouldnt advocate bridge work in this stuff.

If your more comfortable sticking to the manual then stick to it.
or start doing some study and learning what other possibilities are available with lithium disilicate.

I can only talk from study and my own experiance. Probably 70-80% of the work i do now is emax and i have not had a single failure with clients that know what there doing.

you preach the manual then in another thread tell us how your firing the crap out of units to "heal" cracks!
NOW THAT IS SOMETHING I WOULD NOT DO, or have ever needed to do, never had a unit crack, and if i did id remake it.

ill take my integeral .1 veneer over your "healed" restorations any day thanks.

 

[disturbed]

ill take my integeral .1 veneer over your "healed" restorations any day thanks.

lol. so would I!