Influence of Surface Treatments on Surface of Four Zirconia Ceramics

Objectives: The aim of this study was to evaluate the effect of different surface treatments on the surface roughness of four different zirconium oxide ceramics. Methods: Four different sintered zirconium oxide ceramic specimens (Cercon®, In-Ceram® YZ, IPS e.max® ZirCAD and Lava™, Ø12 mm x 11 mm x 1 mm) were treated with (n = 4): (1) Neodymium:yttrium–aluminium–garnet (Nd:YAG) laser was applied with 300-µm fiber probe at 3W, 20Hz, 150 mJ with 100µs pulse duration after the graphite powder on the ceramic surface; (2) CoJet™ Sand sandblasting with silica powder (30 µm particle size) at a pressure of 3.0 bar, distance of 10 mm, perpendicular to the treated surface for 20 s; (3) 9.5% HF acid etching for 90s; (4) no treatment. Ceramic specimens' surfaces were analyzed by Atomic Force Microscope (AFM) recording average surface roughness (Ra) measurements of the substrate. Four measurements were performed for each pre-treated ceramic specimen using a standardized rectangular spot. Data were statistically analyzed by two-way ANOVA and Tukey HSD tests (α = 0.05). The same discs were evaluated under Scanning Electron Microscope (SEM) for surface topography analysis. Results: Significant changes in all zirconium oxide ceramic surfaces roughness occurred after laser irradiation (p<0.05). No differences in ceramic surfaces roughness occurred after any of the CoJet Sand and HF acid etching treatments compared to no treatment groups (p>0.05). Conclusion: Nd:YAG laser irradiation resulted in an increase of surface roughness but the other surface texture parameters behaved similarly with no significant increase of Ra values. However, Nd:YAG laser irradiation induced cracking on the surfaces of all specimens, in addition to a blackening effect.