I want to bond zirconia. My lab says that it can be bonded with CoJet (ESPE/3M). Another lab says it can't be bonded, so just cement it. What do you recommend?

Zirconia can be bonded.  The adhesive Panavia F 2.0 (Kuraray) directly adheres to alumina¹ and zirconia², without the need for any special primer. (Similarly, Bistite 2 DC (Tokuyama) directly adheres.)  Additionally CoJet (and the lab version, Rocatec) can bond zirconia but it more expensive and most likely not as good as Panavia.

For many years, silane has been used to bond to HF etched silica ceramics. Recently, clinicians have been confused about the use of silane on the newer, non-etchable ceramics such as alumina and zirconia. On such ceramics, silane does not yield a stable bond.³  In an attempt to eliminate confusion and create a more "universal" bonding protocol,  Clearfil Ceramic Primer (Kuraray) was introduced to bond both HF-etchable silica based ceramics and other non-etchable ceramics, such as alumina and zirconia.  This Primer combines silane for silica ceramics and the 10-MDP adhesive monomer of Panavia, a monomer which bonds to alumina, zirconia (and also metal). As with Clearfil Porcelain Bond⁴, HF etching of the etchable ceramic is not required; just sandblasting is used as is done to the non-etchable ceramics.  The Primer eliminates the need to use an adhesive-containing luting composite such as Panavia or Bistite. Instead a more conventional composite without a built-in adhesive monomer may be used.

Besides improving retention and marginal seal, another compelling advantage of bonding is "reinforcement" of the all ceramic restoration.  One investigation⁵ reported about 55 percent increase in strength when comparing luting of Procera (Nobel) with Panavia F 2.0 and zinc phosphate. A weaker "self-etching adhesive", Unicem (3M / ESPE) provided only about 10 percent strength increase over zinc phosphate while exhibiting much increased microleakage compared to Panavia F 2.0.  There is evidence that Panavia 21 is more stable on zirconia than is Panavia F 2.0.

References.

1. Kern M and Thompson VP, Bonding of glass infiltrated alumina ceramic: Adhesive methods and their durability., J Prosth Dent 1995;73:240-249.

2.  Wolfart et al., Durability of resin bond strength to zirconia ceramics using different surface conditioning methods,, Dental Mater 2006; 23:45-50.

3.  Kern M and Thompson VP, Bonding of glass infiltrated alumina ceramic: Adhesive methods and their durability., J Pros Dent 1995;73:240-249.

4.  Llobell A et al., Fatigue span of porcelain repair systems. Int J Pros 1992;5:205-213

5.  Oppes S et al., Fracture strength of Procera alumina crowns, IADR 2006, abstract #2090.

Source: Fifth Quarter Seminars
Author: Ray Bertolotti
Posted here: June 15, 2008