Journal of Adhesion Science and Technology, Vol.29, No.12, 1190-1199, 2015
Bond strength of short-pulsed laser-irradiated zirconia to veneer ceramic
Objective: The aim was to evaluate the effect of 1064nm Yb-doped fiber-based nanosecond pulsed laser on surface roughness and bond strength between veneer ceramic and zirconia. Material and methods: Zirconia discs were divided into three groups: sandblasted (SB), laser irradiated (YL), and control (n = 12). YL group was treated with ytterbium laser with the setting of 85W/25kHz. Sandblasting was done using 50 mu m Al2O3 particles from a distance of 10mm for 20s under 3.5atm. No surface treatment was applied to the control group. The surface roughness values and SEM images of the groups were obtained. X-ray diffraction analysis was applied to a spare sample of each group to determine the monoclinic phase ratio. The samples were subjected to shear bond strength (SBS) test with a cross-head speed of 1mm/min after being veneered. The fracture modes were evaluated. One-way analysis of variance and Tukey's HSD tests were used for statistical analysis. Results: The YL group had higher surface roughness than the control (p <= 0.0001) and the SB group (p = 0.007) with a mean value of 2.90 mu m. The SEM images of the groups supported this result, but formation of the microcracks was more intense for the YL group. The monoclinic phase ratio was highest for the SB group. However, the differences of SBS between SB and YL groups were not statistically significant. Mostly the combined failure of samples was observed. Conclusions: Ytterbium laser treatment increased the surface roughness of zirconia, but the SBS was not higher than sandblasting. Surface roughness results did not correlate with the SBS results.