Improving Bond Strength of Translucent Zirconia Through Surface Treatment With SiO2-ZrO2 Coatings
Translucent monolithic zirconia ceramics have been applied in dental clinics due to their esthetic translucent formulations and mechanical properties. Considering inherent ceramic brittleness, adhesive bonding with resin composite increases the fracture resistance of ceramic restorations. However, zirconia is a chemically stable material that is difficult to adhesively bond with resin. To investigate the influences of SiO2-ZrO2 coatings on adhesive bonding of zirconia and the surface characterization of those coatings. Translucent zirconia discs were classified into groups based on surface treatments: CT (control), SB (sandblasting), C21(SiO2:ZrO2=2:1), C11(SiO2:ZrO2=1:1), and C12 (SiO2:ZrO2=1:2) (n=10). Surface characterization of coatings on zirconia were analyzed by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), surface roughness assessment (Ra), X-ray diffraction (XRD), water contact angle (WCA), translucency parameter (TP), and shear bond strength (SBS). Two-way ANOVA for shear bond strength results and ANOVA for Ra and WCA were performed. SEM images revealed SiO2 islands on zirconia disks coated with SiO2-ZrO2. Surface roughness of C12, C11, and C21 groups was significantly larger than those of groups SB and CT (p<0.05). XRD results showed that phase transformation of zirconia disks was detected only in the SB group. In addition, SiO2-ZrO2 coatings reduced WCA. The translucency decreased only in group C21. Group C11 showed the highest shear bond strength under both aging conditions. SiO2-ZrO2 coating is a promising method to enhance the adhesive resin bonding of translucent zirconia without causing phase transformation of translucent zirconia.SUMMARY
Background
Objectives
Methods and Materials
Results
Conclusion
Experimental design.
SEM images of the surface of the translucent zirconia with sintered (CT group) and sandblasting (SB group) at a magnification of 200 ×, 1000×, and 20,000×. In the CT group, the surface of translucent zirconia appeared to be smooth. In the SB group, the surface of translucent zirconia was irregular and rougher.
SEM images of the surface of the coated translucent zirconia for C21 group, C11 group and C12 group at a magnification of 200×, 1000×, and 20,000×. In C21, C11, and C12 groups, many “SiO2 islands” were observed on the surface of translucent zirconia (B, E, H-yellow circles); many zirconium atoms were embedded in SiO2 islands of C21 and C11 groups (C, F, I-red arrows). However, the valleys of group C12 were shallower than those of other groups, rendering a honeycomb structure (B, D-blue squares).
EDX patterns and elemental composition of translucent zirconia specimens after the various treatments. The results showed the distribution of elements in all groups and the mass fraction of each element. Abbreviations; CT: sintered, C21, C11 and C12: SiO2/ZrO2 = 2:1, 1:1 and 1:2); SB: sandblasting.
EDX mapping of the spatial distribution of elements Zr, Si, and O in the ZrO2-SiO2 coatings. Zr and O elements were detected in any groups. Al was detected by sandblasting group and Si was detected in SiO2-ZrO2coating groups. Abbreviations: C21, C11 and C12: SiO2/ZrO2 = 2:1, 1:1 and 1:2; CT, sintered, SB: sandblasting.
XRD patterns of translucent zirconia specimens with the various surface treatments: Tetragonal (T) phase and cubic (C) phase structure could be detected on the surface of any translucent zirconia surface. The monoclinic phase was detected on the surface of translucent zirconia specimens with sandblasting treatments. Abbreviations: C21, C11 and C12: SiO2/ZrO2 = 2:1, 1:1 and 1:2; CT: sintered; SB, sandblasting.
Contributor Notes
†Tiehan Cui and Qiao Du contributed equally to this work.