Morphological analysis of three zirconium oxide ceramics: Effect of surface treatments

To evaluate the effect of different chemo-mechanical surface treatments on the morphology of three recently marketed dental zirconia ceramics.

Ceramic discs (Ø 10 mm x 1 mm height) were obtained from three sintered zirconia ceramics (Lava, Cercon, and Aadva Zr) and treated with: (1) airborne particle abrasion with 125 microm Al(2)O(3) particles (S); (2) selective infiltration etching (SIE); (3) experimental hot etching solution applied for 30 min (ST); (4) no treatment (C). Five discs per group were used for surface roughness analysis using an atomic force microscope (AFM). Data were statistically analyzed by Kruskall-Wallis analysis of variance and Mann-Whitney tests (alpha<0.05). The same discs were evaluated under SEM for surface topography analysis. Three discs per group were cemented to a composite overlay (Paradigm MZ100) with a total-etch resin luting agent (Calibra) and cross-section interfacial analysis was performed under SEM.

Airborne particle abrasion improved the average surface roughness of Cercon and Lava (p<0.05) while SIE induced significant changes on Lava and Adava Zr. Statistical differences in surface roughness were recorded after selective infiltration etching when compared to no treated group, independently from the zirconia type. SEM and AFM analyses revealed changes in surface topography for all the tested ceramics and intergrain spaces opening, especially after ST. The effectiveness of the tested chemo-mechanical surface treatments depends on the zirconia type. The hot experimental etching solution increased the surface roughness of all the tested ceramics creating retentive micro-spaces that may potentially improve zirconia/resin cement interfacial strengths.