Does flexural strength of zirconia affect tooth wearing?

[Ros Russle]

Someone told me that the bending strength of zirconia will affect tooth wearing. I really doubt it. Is there anyone can help me to figure out this question?

 

[a3dl]

Not flexural strength. Abrasiveness can without proper glazing or polishing techniques.

 

[Ros Russle]

Not flexural strength. Abrasiveness can without proper glazing or polishing techniques.

Thx, got it

 

[grantoz]

no its how well its polished there is a aidite claim that their 650mpa layer is less abrasive than the stronger layer which is about 900mpa its pretty bogus conclusion.

 

[Ros Russle]

no its how well its polished there is a aidite claim that their 650mpa layer is less abrasive than the stronger layer which is about 900mpa its pretty bogus conclusion.

I read some articles, it's about the hardness of the materials. Normally, the zirconia 's VH is about 1200Mpa·m², but enamel of the tooth is just around 280Mpa·m². So the best way is to glaze, right?

 

[Chalky]

I read a study that was done by a university in Japan or Korea... it tested traditional pfm against polished zirconia and glazed zirconia of various mpa's. they set up an abrasion test that agitated extracted premolar teeth (from ortho extractions - so they were all health pre molars). the pfm's consistently had significantly greater abrasion when compared to both zirconia groups - under the microscope the surface was more 'textured' which aided abrasion. in the zirconia groups the the polished zirconia had consistently the least amounts of wear (compared to glazed zirconia). under the microscope the polished zirconia had a much smoother surface structure hence causing less wear, whereas the glazed zirconia had slightly more texture on the surface which also aided abrasion, albeit less so than the pfm's in the test. they also concluded that it was less to do with the flexural strength of the material, and more so the surface texture. the wear of the 700mpa zi vs the 1200mpa groups (from memory) were almost identical.
I will endeavour to find the study... it was a very interesting read.
having said all of this, it was just one study and I am sure there are those that will dispute or rebut this idea. it kinda makes good sense to me though, it always depends on the case - each patient is different, they function differently, have a unique oral environment and the conditions of an experiment are controlled, unlike the real world!

 

[Contraluz]

So the best way is to glaze, right?

Polishing the occlusal surface is the best way to 'protect' your opposing dentition. Unpolished Zr is about the worst that can happen to a natural tooth and/or a conventional pfm (speaking from experience...) DVA has a couple polishing compounds and I recently started using a 'polishing bristle' (can't remember the brand) to prepolish and then high shine with the compound. I then still glaze/color on top of it. The glaze will wear out over time and the high shine surface will appear.

 

[user name]

My memory tells me its the leucite crystals that are the abrasive componentin porcelain. Im guessing they are present in glaze as well?
Back when Ceramco had the Finesse line of porcelain, I was thinking they advertised reduced leucite content, so kinder to opposing dentition. I dont have a clue how different glazes stackup.

 

[OpalEssence]

Flexural strength means bending strength, means torsion... How would a flexural strength affect the wear of a tooth ?? I think what you mean is the hardness of Zr. for example porcelain will wear down its opposing if it is acrylic because it is harder not because of its flexural strength ! i dunno i hope i'm wrong

 

[Contraluz]

How would a flexural strength affect the wear of a tooth ?

Not sure either. The only thing I can imagine is, in order to get zirconia more translucent, the formula is changed and it is different to the more opaque and higher MPa ones. Hence it's more abrasive?

Although, the newest generation of Zr is translucent and maintains the higher flexure strength.

 

[grantoz]

prettau 2 dispersive has very little change in strength yet its great trans in the incisal 3rd .

 

[Patrick Coon]

I read a study that was done by a university in Japan or Korea... it tested traditional pfm against polished zirconia and glazed zirconia of various mpa's. they set up an abrasion test that agitated extracted premolar teeth (from ortho extractions - so they were all health pre molars). the pfm's consistently had significantly greater abrasion when compared to both zirconia groups - under the microscope the surface was more 'textured' which aided abrasion. in the zirconia groups the the polished zirconia had consistently the least amounts of wear (compared to glazed zirconia). under the microscope the polished zirconia had a much smoother surface structure hence causing less wear, whereas the glazed zirconia had slightly more texture on the surface which also aided abrasion, albeit less so than the pfm's in the test. they also concluded that it was less to do with the flexural strength of the material, and more so the surface texture. the wear of the 700mpa zi vs the 1200mpa groups (from memory) were almost identical.
I will endeavour to find the study... it was a very interesting read.
having said all of this, it was just one study and I am sure there are those that will dispute or rebut this idea. it kinda makes good sense to me though, it always depends on the case - each patient is different, they function differently, have a unique oral environment and the conditions of an experiment are controlled, unlike the real world!

This correlates with a study out of the University of Zurich from 2009 or 2011. it is more about the surface texture of zirconia than flexural strength or hardness. This study showed that highly polished zirconia is kinder to the opposing dentition than even enamel.