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Phosphate groups have a very strong affinity to zirconia. The use
of phosphoric acid on zirconia should always be avoided, since the
phosphate groups will effectively block any subsequent adhesive
monomer fromreactingwith thezirconia. One recommendedmate-
rial to effectively clean the surface of the zirconia prior to cementa-
tion is to use a mixture of zirconia powder and sodium hydroxide.
An alternative approach for zirconia bonding is to apply a
surface primer to mediate the adhesive bond to the zirconia. Some
universal primers, such as Monobond Plus or Clearfil Ceramic
Primer, can create adhesive bonds to zirconia
6
(Fig. 2). Zirconia-
specific primers containing organophosphate and carboxylic
monomers, such as Z-Prime Plus, can develop adhesive bonds
to zirconia after airborne-particle abrasion.
7
Resin cements or
bonding systems, such as the newest Universal Bonding Agents,
containing 10-MDP have also been reported as capable of devel-
oping bonds with zirconia (Fig. 3). Laboratory studies indicate
satisfactory bonding to zirconia with this approach; however,
these agents are prone to hydrolytic degradation following ther-
mocycling over time that leads to questions about the longevity of
the adhesive bond to zirconia.
Published systematic reviews of zirconia adhesive bonding
generally agree that airborne-particle abrasion is effective in
increasing surface roughness, and that it is a useful pretreatment
for zirconia. But it is not effective without a zirconia-specific
adhesive monomer to mediate a bond. Tribochemical silica
coating is the most effective airborne-particle abrasion tech-
nique for creating adhesive bonds to zirconia. And, current
laboratory data questions the potential longevity of the adhe-
sive bond to zirconia due to hydrolytic degradation.
Another complicating factor to consider when developing
an adhesive bond to zirconia is that the vast majority of adhesive
resin cements are light-cured. Zirconia is a more opaque material
compared to other chairside CAD/CAM glass ceramics, and will
act to restrict light energy penetration through the restoration.
Any resin cement considered for zirconia restorations should have
a strong self-cure or chemical-cure capability.
Although some laboratory studies are encouraging for devel-
oping adhesive bonds to zirconia, there is little-to-no published
clinical data on long-term viability. Considering that the high-
strength properties of zirconia allow for mechanically retentive
preparations, and that most clinicians would prefer an easy and
efficient cementation technique, resin-modified glass ionomers
or glass ionomer cements are generally the preferred and recom-
mended cements for zirconia restorations.
For questions and more information, Dr. Fasbinder can be reached
at
.
REFERENCES
1 GuazzatoM, AlbakryM, Ringer SP, SwainMV. Strength, fracture toughness and
microstructure of a selection of all-ceramic materials. Part II. Zirconia-based dental
ceramic. Dent Mater 2004b;20:449-456.
2 Matinlinna JP, Heikkinen T, ÖzcanM, Lassila LV, Vallittu PK. Evaluation of resin
adhesion to zirconia ceramic using some organosilanes. Dent Mater 2006;22:824-831.
3 Quaas AC, Yang B, KernM. Panavia F 2.0 bonding to contaminated zirconia ceramic
after different cleaning procedures. Dent Mater 2007;23: 506-512.
4 Tzanakakis EC, Tzoutzas IG, Koidis PT. Is there a potential for durable adhesion to
zirconia restorations? A systematic review. J Prosthet Dent 2016; 115:9-19.
5 OzcanM, Bernasconi M. Adhesion to zirconia used for dental restorations: A systematic
review andmeta-analysis. J Adhes Dent 2015; 17: 7–26.
6 Attia A, KernM. Long term resin bonding to zirconia with a universal primer.
J Prosthet Dent 2011;106:319-27.
7 Magne P, ParanhosM, Burnett L. New zirconia primer improves bond strength of
resin-based cements. Dent Mater 2010;26:345-52.
Fig. 1: CoJet Sand is a
30-micron blast-coating
agent for tribochemical silica coating
Fig. 2 (left):
Commercially
available zirconia
primers
Fig. 3 (below):
Universal bonding
agents containing
10-MDP
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