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Interesting fatigue study
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john kanca



Joined: 14 May 2005
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PostPosted: Mon Sep 20, 2010 7:24 pm    Post subject: Interesting fatigue study Reply with quote

J Prosthet Dent. 2010 Sep;104(3):149-57.

In vitro fatigue resistance of CAD/CAM composite resin and ceramic posterior occlusal veneers.
Magne P, Schlichting LH, Maia HP, Baratieri LN.

Abstract
STATEMENT OF PROBLEM: Thin, bonded, posterior occlusal veneers constitute a conservative alternative to traditional complete coverage crowns. Information regarding selection of the appropriate material and its influence on fatigue resistance, which may affect the longevity of the restoration, is missing.

PURPOSE: The purpose of this study was to assess and compare the fatigue resistance of composite resin and ceramic posterior occlusal veneers.

MATERIAL AND METHODS: Thirty extracted molars received a standardized nonretentive tooth preparation (simulating advanced occlusal erosion), including removal of occlusal enamel, exposure of dentin, and immediate dentin sealing (Optibond FL). All teeth were restored with a 1.2-mm-thick occlusal veneer (Cerec 3 chairside CAD/CAM system). The restorations (n=10) were milled from leucite-reinforced and lithium disilicate ceramics (IPS Empress CAD and IPS e.max CAD, respectively) and a composite resin (Paradigm MZ100). The intaglio surfaces of the ceramic restorations were conditioned by hydrofluoric acid etching and silane. Airborne-particle abrasion and silane were used to condition the composite resin restorations. Preparations were airborne-particle abraded and etched. All restorations were bonded with preheated luting material and submitted to cyclic isometric loading at 5 Hz, starting with a load of 200 N (x5000 cycles), followed by stepwise loading of 400, 600, 800, 1000, 1200, and 1400 N at a maximum of 30,000 cycles each. The number of cycles at initial failure (first cracks) was recorded. Specimens were loaded for a maximum of 185,000 cycles. Groups were compared using the life table survival analysis (alpha=.016, Bonferroni method).

RESULTS: IPS Empress CAD failed at an average load of 900 N, with no specimen withstanding all 185,000 load cycles (survival 0%), while IPS e.max CAD and Paradigm MZ100 demonstrated survival rates of 30% and 100%, respectively. None of the specimens exhibited catastrophic failure, but only cracks limited to the restorative material.

CONCLUSIONS: Posterior occlusal veneers made of composite resin (Paradigm MZ100) had significantly higher fatigue resistance (P<.002) compared to IPS Empress CAD and IPS e.max CAD.
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priior



Joined: 10 Feb 2009
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PostPosted: Mon Sep 20, 2010 9:02 pm    Post subject: Reply with quote

someone send this study to Gordon? Smile
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Pav



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PostPosted: Tue Sep 21, 2010 4:31 am    Post subject: Reply with quote

John,

Could you help us understand this study a bit better please? Z100 is to my knowledge is a composite. This study suggests that there is more to failure than "hardness", how is it that leucite failed, emax did ok-ish and Z100 did so well?

I'm fully prepared for a material lesson Cool
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john kanca



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PostPosted: Tue Sep 21, 2010 6:01 am    Post subject: Reply with quote

Pav wrote:
John,

Could you help us understand this study a bit better please? Z100 is to my knowledge is a composite. This study suggests that there is more to failure than "hardness", how is it that leucite failed, emax did ok-ish and Z100 did so well?

I'm fully prepared for a material lesson Cool


It appears that the Z100 composite has better fatigue resistance, or fracture toughness. It's not as britttle as the ceramics. I found this data intriguing.
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Pav



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PostPosted: Tue Sep 21, 2010 8:04 am    Post subject: Reply with quote

john kanca wrote:
Pav wrote:
John,

Could you help us understand this study a bit better please? Z100 is to my knowledge is a composite. This study suggests that there is more to failure than "hardness", how is it that leucite failed, emax did ok-ish and Z100 did so well?

I'm fully prepared for a material lesson Cool


It appears that the Z100 composite has better fatigue resistance, or fracture toughness. It's not as britttle as the ceramics. I found this data intriguing.


I love the way you're cryptic with your clues!

So the question now becomes WHY did you find this intriguing?

Thanks!
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priior



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PostPosted: Tue Sep 21, 2010 8:22 am    Post subject: Reply with quote

do you think the results would be any different if the composite was done directly?
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john kanca



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PostPosted: Tue Sep 21, 2010 9:58 am    Post subject: Reply with quote

priior wrote:
do you think the results would be any different if the composite was done directly?


Probably, and it would depend on who placed it and the adhesive used.
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john kanca



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PostPosted: Tue Sep 21, 2010 9:59 am    Post subject: Reply with quote

Pav wrote:
john kanca wrote:
Pav wrote:
John,

Could you help us understand this study a bit better please? Z100 is to my knowledge is a composite. This study suggests that there is more to failure than "hardness", how is it that leucite failed, emax did ok-ish and Z100 did so well?

I'm fully prepared for a material lesson Cool


It appears that the Z100 composite has better fatigue resistance, or fracture toughness. It's not as britttle as the ceramics. I found this data intriguing.


I love the way you're cryptic with your clues!

So the question now becomes WHY did you find this intriguing?

Thanks!


I don't know for certain that this would translate directly to clinical experience. A study would need to be done to clear the fog.
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Howardmg



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PostPosted: Wed Sep 22, 2010 8:28 am    Post subject: Reply with quote

I often wondered about this...
We often use a very thin layer of composite in fissures on molars. Assuming you can construct porcelain that thin, either by lab or Cerec would you feel comfortable bonding that over the fissures?
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john kanca



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PostPosted: Wed Sep 22, 2010 11:58 am    Post subject: Reply with quote

Howardmg wrote:
I often wondered about this...
We often use a very thin layer of composite in fissures on molars. Assuming you can construct porcelain that thin, either by lab or Cerec would you feel comfortable bonding that over the fissures?


Not me.
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brad



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PostPosted: Wed Sep 22, 2010 2:19 pm    Post subject: Reply with quote

why would you want to do that?
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john kanca



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PostPosted: Wed Sep 22, 2010 6:44 pm    Post subject: Reply with quote

Howard always wanted to do Cerec pit and fissures sealants.

Laughing
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Howardmg



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PostPosted: Sun Sep 26, 2010 2:56 pm    Post subject: Reply with quote

Guys....it was a rhetorical question!!

The point I was trying to make (obviously unsucessfully Smile ) was that you WOULDN'T use porecelain as thin as we use composite..
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Howardmg



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PostPosted: Wed Sep 29, 2010 10:32 pm    Post subject: Reply with quote

John -
Hypothetical question....
Second molar. Heavy bruxer who refuses a night guard. Traditional gold crown prep would not be retentive because of lack of erupted tooth structure and patient refuses perio surgery. So we need to do a non retentive prep (with resistance form) and bond to tooth. Material will be only 1mm thick on the occlusal. Would you do E Max or Composite crown?
Thanks...Howard


Actually not so hypothetical. Patient lost gold crown I did a year ago because there is not retention.... My bad for doing it..
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john kanca



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PostPosted: Thu Sep 30, 2010 6:04 am    Post subject: Reply with quote

Howardmg wrote:
John -
Hypothetical question....
Second molar. Heavy bruxer who refuses a night guard. Traditional gold crown prep would not be retentive because of lack of erupted tooth structure and patient refuses perio surgery. So we need to do a non retentive prep (with resistance form) and bond to tooth. Material will be only 1mm thick on the occlusal. Would you do E Max or Composite crown?
Thanks...Howard


Actually not so hypothetical. Patient lost gold crown I did a year ago because there is not retention.... My bad for doing it..


If it's up to me I'd bond on the gold crown.
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