A parametric study of laser interference surface patterning of dental zirconia: Effects of laser parameters on topography and surface quality

- Direct Laser Interference Patterning was applied to introduce micrometric periodical topographies on the surface of 3Y-TZP.
- Pattern geometry and roughness can be tuned independently by adjusting laser setup and parameters.
- High fluence and low number of pulses produce patterns with higher quality.
- Microcracking, porosity and redepostion of material appear at certain conditions.

ObjectiveThe aim of this work is to generate micrometric linear patterns with different topography on dental grade zirconia by means of UV laser interference and to assess the quality of the produced surface, both in term of the geometry produced and of the surface damage induced in the material.MethodsThe third harmonic of a Q-switched Nd:YAG laser (355 nm, pulse duration of 10 ns and repetition rate of 1 Hz) was employed to pattern the surface of 3Y-TZP with micrometric-spaced lines. The resulting topography was characterized with White Light Interferometry and Scanning electron microscopy: pattern depth (H), amplitude roughness parameters (Sa, filtered-Sa), Fourier spatial analysis and collateral damages were related to laser fluence and number of pulses employed.ResultsWith our experimental setup, line-patterning of zirconia surfaces can be achieved with periodicities comprised within 5 and 15 μm. Tuning laser parameters allows varying independently pattern depth, overall roughness and surface finish. Increasing both fluence and number of pulses allows producing deeper patterns (maximum achievable depth of 1 μm). However, increasing the number of pulses has a detrimental effect on the quality of the produced lines. Surface damage (intergranular cracking, open porosity and nano-droplets formation) can be generated, depending on laser parameters.SignificanceThis work provides a parametric analysis of surface patterning by laser interference on 3Y-TZP. Best conditions in terms of quality of the produced pattern and minimum material damage are obtained for low number of pulses with high laser fluence. With the employed method we can produce zirconia materials with controlled topography that are expected to enhance biological response and mechanical performance of dental components.

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