The use of MDP-based materials for bonding to zirconia.
BACKGROUND
A strong and stable bond between the luting resin and overlying ceramic restoration is critical to longevity, but no technique has been established for how to provide such a bond when the core material is zirconia.


OBJECTIVE
The purpose of this study was to evaluate the effect of different materials containing 10-methacryloyloxydecyl dihydrogen phosphate (MDP) on the bond strength to yttria-tetragonal zirconia polycrystal (Y-TZP) ceramic.


METHODS
Forty Y-TZP slices (Lava) were cemented to substrates (8 groups; n=5 in each) with or without the previous application of an experimental primer (0.5% MDP) or an MDP-based adhesive (Clearfil S3 Bond Plus or Scotchbond Universal) with either an MDP (Clearfil SA) or a non-MDP (RelyX Ultimate) luting resin. Specimens were cut, stored in distilled water, and microtensile tested (5 beams per specimen) at 48 hours and again at 6 months after luting procedures. The data were analyzed by 4-way ANOVA (α=.05) and the Tukey test (α=.05). The mode of failure was classified with a stereomicroscope, and the treated surfaces were analyzed with energy-dispersive x-ray spectroscopy.


RESULTS
Both adhesive (P<.001) and time (P<.001) significantly affected bond strength. The interaction of any of the factors was not significant. The use of an MDP-containing adhesive and the shorter storage time were associated with higher bond strengths. At 48 hours, an overall incidence of 50.5% of Type 1 mode of failure (adhesive at ceramic/resin interface) occurred, as opposed to 68% after 6 months of water storage. Energy-dispersive x-ray spectroscopy results showed peaks of carbon and phosphorus when MDP-based materials were used.


CONCLUSIONS
The application of an MDP-based adhesive may improve bond strength to zirconia. However, microtensile bond strength results for all groups did not remain stable over 6 months.
Assistant Professor, Department of Clinical Sciences, Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada. Electronic address: grace.desouza@dentistry.utoronto.ca.
Grace
G
de Souza
Graduate student, Institute of Chemical Technology of Materials Synthesis, Faculty of Chemistry and Pharmacy, University of Würzburg, Würzburg, Germany.
Diana
D
Hennig
Student, Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada.
Anuj
A
Aggarwal
Professor, Department of Clinical Sciences, Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada.
Laura E
LE
Tam
D002244:Carbon / Q000032:analysis; D002484:Cementation / Q000379:methods; D001840:Dental Bonding; D003799:Dental Stress Analysis / Q000295:instrumentation; D017220:Dentin-Bonding Agents / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D010758:Phosphorus / Q000032:analysis; D058105:Polymerization; D019279:Resin Cements / Q000737:chemistry*; D013052:Spectrometry, X-Ray Emission; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength; D013997:Time Factors; D014867:Water / Q000737:chemistry; D015019:Yttrium / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry*
C505694:Clearfil S3 Bond; C581302:Clearfil SA; D017220:Dentin-Bonding Agents; D008689:Methacrylates; C528569:Rely-X; D019279:Resin Cements; C499362:yttria stabilized tetragonal zirconia; D014867:Water; D010758:Phosphorus; D015019:Yttrium; D002244:Carbon; C069749:methacryloyloxydecyl dihydrogen phosphate; C041330:Scotchbond; D015040:Zirconium