Zirconia degrading in the oral environment

[Baobabtree]

Hi everyone, just had an interesting conversation with a customer of mine who says that he has heard that zirconia begins to weaken/break down in the oral environment after 10 years or so. It's news to me. Anyone else heard of this? TIA

 

[2thm8kr]

I have read somewhere that traditional zirconia loses half it's strength(mpa) in 5 years and levels off after that.

 

[Car 54]

I've read and heard the same thing, it weakens over time in the oral environment.

Not sure of how much or how long. I'm sure if it's Googled someone like Pubmed etc has some numbers.

 

[Patrick Coon]

He is referring to Low Temperature Degradation (LTD). This was a phenomenon with older (1st gen) zirconias that when exposed to a warm, wet environment they would break down over time.

Newer zirconias have been developed to reduce this effect. Can it still happen, yes, but is much less likely.

The other thing to consider is, how long do you consider the the lifespan of a restoration? I believe for insurance purposes it is 5 years. I personally would consider it longer (10 years) depending on the patient's oral hygiene. In these cases the 5-10 gear span would be acceptable anyways. But this is not necessarily the case.

 

[rkm rdt]

We'll be all out of a job in 5 years.
carry on...

 

[JohnWilson]

Its the 400 full arch zirconia implant cases that I am thinking of. Will be super interesting to see what happens if this stuff starts to show its Achilles heel.

 

[Car 54]

He is referring to Low Temperature Degradation (LTD). This was a phenomenon with older (1st gen) zirconias that when exposed to a warm, wet environment they would break down over time.

Newer zirconias have been developed to reduce this effect. Can it still happen, yes, but is much less likely.

The other thing to consider is, how long do you consider the the lifespan of a restoration? I believe for insurance purposes it is 5 years. I personally would consider it longer (10 years) depending on the patient's oral hygiene. In these cases the 5-10 gear span would be acceptable anyways. But this is not necessarily the case.

Can it also depend on the quality of the zirconia and the vendor and what grade of zirconia their using? In other words, does buying your (labs) zirconia
discs from a reputable vendor help?

edit: It's probably a self answering question, but I'm sure that even though the zirconia may be of a newer generation, not all zirconias are created equal as far as the quality that is being used and sold cheaply.

 

[Patrick Coon]

Can it also depend on the quality of the zirconia and the vendor and what grade of zirconia their using? In other words, does buying your (labs) zirconia
discs from a reputable vendor help?

edit: It's probably a self answering question, but I'm sure that even though the zirconia may be of a newer generation, not all zirconias are created equal as far as the quality that is being used and sold cheaply.

Of course I would buy from a reputable dealer, and I can say why we believe our is better than others, but. . .

. . . Most companies buy their are materials from the same sources. But it also will depend on what is added to those powders and how they are processed. I would always look for a manufacturer that has their material tested and 510k certified by the FDA or other international standard (because not all do).

 

[Car 54]

Thank you, Patrick.

 

[Baobabtree]

He is referring to Low Temperature Degradation (LTD). This was a phenomenon with older (1st gen) zirconias that when exposed to a warm, wet environment they would break down over time.

Newer zirconias have been developed to reduce this effect. Can it still happen, yes, but is much less likely.

The other thing to consider is, how long do you consider the the lifespan of a restoration? I believe for insurance purposes it is 5 years. I personally would consider it longer (10 years) depending on the patient's oral hygiene. In these cases the 5-10 gear span would be acceptable anyways. But this is not necessarily the case.

Thanks Patrick, it is interesting that docs and patients expectations seem to be one that the restorations will last perhaps for the rest of their lives. At least that is my impression. With the LTD phenomenon you've alluded to, was it conducted in a lab environment or from data of restorations placed in patients mouths?

 

[Patrick Coon]

Of course this is all based on laboratory testing, in an autoclave. When I read the test reports, I wonder whose mouth is 95C and 3 bar pressure. I'm not convinced that (personally) LTD is a phenomenon that actually pertains to dental restorations. I think that we need to see what happens over the next 5-10 years to see if it shows up in the real world.

 

[Baobabtree]

Of course this is all based on laboratory testing, in an autoclave. When I read the test reports, I wonder whose mouth is 95C and 3 bar pressure. I'm not convinced that (personally) LTD is a phenomenon that actually pertains to dental restorations. I think that we need to see what happens over the next 5-10 years to see if it shows up in the real world.

Thanks Patrick.

 

[KIM]

Thanks Patrick.

This situation was first recognized in zirconia hip replacements, quite a few years ago.

 

[cadfan]

it was part of stone time zircon but today see below

https://www.google.de/url?url=https...-yIdIA&usg=AFQjCNH3EDZEYxyucYvErVukEhScRDQblQ

 

[rkm rdt]

This situation was first recognized in zirconia hip replacements, quite a few years ago.

Yes @CatamountRob has been looking to move to flatter land.

 

[Getoothachopper]

This situation was first recognized in zirconia hip replacements, quite a few years ago.

I'm having a 'hell of a time' milling out these Zirconia Hips in my Zenotec Mini

 

[rkm rdt]

I'm having a 'hell of a time' milling out these Zirconia Hips in my Zenotec Mini

Maybe you're not hipa compliant.

 

[BobCDT]

Just about all the HT materials (1100 MPh) loose 50% of their flexural strength over 5 years. That said the new Anterior materials (about 600 MPh) made form Zepex , Tosoh powder loose virtually no strength over time. This is one of the only ceramic materials in our industry that has no degradation or loss of strength over time. lithium disilicate, feldspathic, lucite ceramics all loose strength. Most are in the 30% + range.
John, you are correct, five years form now all the full arch screw retained zirconia cases will have a decreased flexural strength of about 500-600 MPa. We will get to do many all over again.

 

[rkm rdt]

Just about all the HT materials (1100 MPh) loose 50% of their flexural strength over 5 years. That said the new Anterior materials (about 600 MPh) made form Zepex , Tosoh powder loose virtually no strength over time. This is one of the only ceramic materials in our industry that has no degradation or loss of strength over time. lithium disilicate, feldspathic, lucite ceramics all loose strength. Most are in the 30% + range.
John, you are correct, five years form now all the full arch screw retained zirconia cases will have a decreased flexural strength of about 500-600 MPa. We will get to do many all over again.

Or somebody else will.

 

[rkm rdt]

I doubt those things will be made in zirconia 5 years from now.