Titanium Surface Nanostructuring by Picosecond Laser Irradiation for Surface Improvement of Dental Abutments

The goal of this study is to demonstrate the capability of high-repetition rate picosecond laser processing as an alternative approach for large-scale surface nanostructuring of Titanium (Ti) dental abutments. We used the second harmonic (532 nm) of the Nd:YVO4 laser source, delivering pulses of about 10 ps duration at 500 kHz repetition rate. Sample surfaces were irradiated in air with various light doses, affecting surface morphologies in both micro- and nano-scales. Scanning electron microscopy analyses revealed the generation of laser-induced periodic surface structures (LIPSS), with feature sizes similar to the laser wavelength. We evidenced that the color of samples surface varied by changing the applied doses due to the gradual oxidation of surfaces. The influence of morphological and chemical surface features (generated by a medium irradiation dose) on viability, proliferation, adhesion and morphology of human mesenchymal stem cells (hMSCs) was evaluated at 3 and 7 days after cell seeding. Immunofluorescence microscopy investigations of the cytoskeleton have shown that all the investigated surfaces promote hMSCs adhesion. We demonstrate that picosecond laser nanostructuring of Ti metallic surfaces is able to modulate hMSCs viability and proliferation through morphological modifications to promote a better cells growth and adhesion as compared with controls after 7 days of culture.