Roughening of Zirconia with Nanosecond Nd:YAG Laser: A Pilot Study

The objective of this study was to evaluate the efficiency of nanosecond pulsed Nd:YAG laser (1064 nm) on the surface roughening of zirconium oxide ceramic.

Method:

Three different zirconium oxide ceramics (Vita In-Ceram Zirconia, 3M-Espe Lava, IPS E-Max ZirCAD) were used for this study. Six specimens with 10×10×1 mm dimensions were prepared for each group. Zirconium oxide core surfaces were ground-finished with a 600-grit silicon carbide abrasive paper. One specimen from each group was randomly selected and served as control. Then Nd:YAG laser irradiation with 80W output power, 50 nanosecond pulse duration and 25 kHz frequency was applied on the zirconia surfaces with a scanning pattern with 300 mm/s scanning speed. Finally the surfaces were analyzed with scanning electron microscope (SEM), atomic force microscope (AFM) and x-ray diffraction analysis (XRD). 

Result:

The relative amounts of monoclinic zirconia detected with XRD on laser irradiated surfaces of the specimens were varied between 16% and 16.85%. The monoclinic content of the control group was 13%. The SEM analysis showed coarsened surface with a uniform presence of irregularities and deeper pits than the control group without presence of microcracks.

Conclusion:

Within the limitations of this pilot study, it can be concluded that using the nanosecond pulsed Nd:YAG laser for roughening may be a promising and effective method for conditioning zirconia surfaces without creating microcracks and reducing the resistance and longevity of the material.