Topographical Surface Changes of Zirconia After Different Surface Treatments

Objectives: The purpose of this study was to investigate the effect of different surface treatments on the roughness of zirconia. Methods: Eighty sintered zirconia ceramic specimens (VITA In-Ceram^® 2000 YZ for inLab^®)  were divided into 4 groups (n=20) according to the surface treatments received: none (control), Er:YAG laser irradiation (AT Fidelis Er:YAG) (400 mJ, 10 Hz, 4 W, 100 MPS, distance: 1 mm), tribochemical silica coating using aluminium oxide (Al₂O₃) modified by silica (30 µm), and air abrasion using Al₂O₃ particles (110 µm). After the surface treatment procedures, the surface roughness (Ra in µm) of the specimens was evaluated using a surface texture measuring instrument (Mitutoyo Suftest 402). Topographical surface changes of zirconia after surface treatments were also evaluated with atomic force microscope (AFM) (Quesant-Ambios Universal Scanning Probe Microscope) and scanning electron microscope (SEM) (LEO 440) analyses. The surface roughness values were analyzed using the Kruskal-Wallis test, followed by multiple pairwise comparisons using the Mann-Whitney U test (p=0.05). Results: The results of the statistical analysis are summarized in table. The Kruskal-Wallis test revealed that there were significant differences among the groups (p<0.001). According to the Mann-Whitney U test, the surface roughness values of the air abrasion group showed statistical significance when compared with the other groups (p<0.05). However, there were no significant differences between the laser and silica groups (p>0.05). Conclusion: According to the results of the statistical and microscopic analyses, all of the surface treatments increased the roughness of zirconia when compared with the control group; however, air abrasion is an effective surface treatment for roughening zirconia.