adhesive bond

[odchamp]

does pressed ceramic have better adhesive qualities over metal?
Forgeting the strength issue, would a pressed ceramic wing adhere better than a metal wing ?

 

[JohnWilson]

The answer is "it depends" on what metal is used and how its treated.

On a general note glass etches better than any metal so the chemical bond is higher.

With that being said special treatment to the wings of Nobel to HN metal crowns "Tin plating" allows for a very good bond. NP alloys that contain nickel also etch well.

 

[rkm rdt]

I'm more interested in the bond strength of the new unicem 2 wrt zirconia wings.

 

[Bobby Orr ceramics]

Zirconia can't be etched. Therefore, can't be truly chemically bonded with an agent. Any zirconia maryland is reliant upon the prep design for retention in relation to the function force applied. Worst case scenario , bridge pops off..... the separation will be between the adhesive and the zirconia.

To boost true bond interface, and if the prep allows, we'll cut back the zirconia as if doing a porcelain margin and press the ceramic for the whole bridge. Etch the porcelain internally and then advise the Dr to Bond with a separate etch, bond, and luting agent. We haven't had any failures......even with posterior onlay bridges.

Be sure to slow cool any of your Zr restorations 15 minutes from the high temp or your units will be prone to chipping and fracture in anyway.

, James

 

[rkm rdt]

I'm more interested in the bond strength of the new unicem 2 wrt zirconia wings.

Unicem 2 is indicted for maryland zirconia bridges according to my 3M rep.

 

[Bobby Orr ceramics]

3M rep is correct. However, to maximize bond strength, nothing beats etching out the leucites in a ceramic and the Dr using a etch, bond agent, luting agent. The Dr can still use Unicem 2 but advise that they etch and bond the teeth prior to Unicem 2. 3M and Ivoclar are masters at selling the "easy" 1 step techniques that come with a price on funky prep designs.

 

[paulg100]

Is there anything yet that beats gen 4 bonding agents?

The last lecture i sat about bonding, generation 4 bonding agents were the only ones that maintained there bond strength after 5 years.

The all in ones etc all tailed off sharply after 5 years.

May be easier but you pay a price for quick fixes.

 

[Bobby Orr ceramics]

Yes. they are the best. However, the Dr must employ specific steps for longevity and no post-op sensitivity. When bonding to dentin, many docs desicate the dentin by drying with air-gun after rinsing etch from tooth......BIG MISTAKE !! no matter what bonding system. Always advise to dry the tooth (after 20 second etch with acid) with cotton roll so the dentinal tubules don't collapse. Collapsed dentinal tubules sacrifice bond strength (no resin tag penetration) and create domes of resin on each tubule causing pressure on each tubule when tooth in function. The pressure causes fluid movement in tubules......hence, post-op sensitivity. DRYING TOOTH PROPERLY IS A POTENTIAL HUGE LANDMINE !!!!

 

[paulg100]

how about bonding to enamel and not dentine

 

[Bobby Orr ceramics]

Same protocol for enamel. Bonding to enamel is always best long term result because the dentin tubules are contained by the Lord's own tubule "capping" system called Enamel..... however, if the abutments are prepped properly for adequate joint thickness for Zr or eMax (anterior),the Dr will be exposing dentin. I always advise the same protocol for dentin and enamel to keep all bases covered....

 

[rkm rdt]

"however, if the abutments are prepped properly for adequate joint thickness for Zr or eMax (anterior),the Dr will be exposing dentin"

I am not a fan of a wing design for emax.A lingual modified bevel of the abutment teeth line angles provides good surface area for bonding,improved mechanical retention,and idealizes the path of insertion .This also eliminates the undesired embrasures associated with winged marylands.