Interaction Between Silicatization and MDP Monomer on Bonding to YTZP

Objective: This study evaluated the effect of different surface activation regimens on the adhesion obtained by MDP-based cement upon the bonding durability to an yttrium stabilized tetragonal zirconia (Y-TZP) ceramic. Methods: Y-TZP blocks (N=96) were embedded in acrylic resin (free surface for adhesion: 5x5 mm), ground finished and randomly divided into four groups (N=24) according to the ceramic surface conditioning (CSC): CSC-1) cleaning with isopropanol (ALC); CSC-2): ALC + phosphoric acid etching + MDP-based primer application (MDP-primer); CSC-3) silica coating + MPS-based coupling agent application (SiO2+MPS-Sil); CSC-4) SiO2+MDP-primer. The MDP-based resin cement was applied on the treated surface using a cylindrical mold (diameter: 3 mm). Half of the specimens from each surface conditioning were stored in distilled water (37°C, 24 h) before testing. The other half of the specimens were stored (90 days) and thermocycled (12000x) during this period (90d/TC) before testing. Shear bond strength (SBS) test was performed at a crosshead speed of 0.5 mm/min. Result: Two factors composed the experimental design: ceramic conditioning strategy (4 levels) and storage conditions (2 levels), yielding to 8 groups. After 90d/TC, SiO2+MDP-primer (24.40 MPa) promoted the highest SBS (Tukey; p<0.05). CSC-1 and CSC-2 groups debonded spontaneously during 90d/TC. Conclusion: Bonding values were higher and more stable in the silicatized groups. The use of MDP-primer after silica coating increased the bond strength.