Surface roughness and morphologic changes of zirconia: Effect of different surface treatment

Purpose: The purpose of this study was to investigate the surface roughness and morphologic changes of pre-sintered ZrO2 after sandblasting and erbium, chromium: Yttrium, scandium, gallium, garnet (Er, Cr: YSGG) laser application of different intensities. Material and Methods: Eighty pre-sintered ZrO2 cylinders (7 mm diameter, 3 mm height) were prepared and divided into eight groups. Specimens in the control group were not treated. The following treatments were applied: Er, Cr: YSGG laser irradiation with different energy intensities (1-6 W at 20 Hz, with air-water cooling proportion of 65%/55%) and air abrasion with Al2O3 particles (120 mu m). Then, all the specimens were sintered. The average surface roughness of each specimen was determined with a profilometer, and the morphology changes of a specimen from each group were evaluated with scanning electron microscope (SEM) analyses. The surface roughness data were analyzed through one-way analysis of variance and Tukey's honestly significant difference test (P < 0.05). Results: There were significant differences between 2 and 6 W irradiations and control group. The highest surface roughness value was obtained with 6 W irradiation (8.14+/-1.26 Ra), followed by the 5 W (7.60+/-1.12 Ra), 4 W (7.50+/-0.90 Ra), 3 W (5.86+/-1.03 Ra), 2 W (4.54+/-0.53 Ra) and sandblasting group (2.18+/-0.92 Ra). 1 W laser irradiation (0.80+/-0.06 Ra) presented Ra values similar to the control group (0.77+/-0.03). Conclusion: The result of the statistical analyses and SEM images showed that Er, Cr: YSGG laser irradiation with 4-6 W/20 Hz presented significantly effect in surface roughness changes of zirconia than other surface treatments.