Laser Surface Pattering of Titanium for Improving the Biological Performance of Dental Implants

Direct laser interference patterning (DLIP) is used to produce periodic line-like patterns on titanium surfaces. An Nd:YAG laser operating at 532 nm wavelength with a pulse duration of 8 ns is used for the laser patterning process. The generated periodic patterns with spatial periods of 5, 10, and 20 µm are produced with energy densities between 0.44 and 2.6 J cm^-2 with a single laser pulse. With variation of energy density, different shapes of the arising topography are observed due to the development of the solidification front of the molten material at the maxima positions. Characterization of the surface chemistry shows that the DLIP treatment enhances the content of nitrogen of the titanium reactive layer from 3.9% up to 23.4%. The structural analysis near the titanium surface shows no changes in microstructure after the laser treatment. Contact angles between 65° and 79° are measured on both structured and turned reference surfaces. Cell viability of human osteoblasts on line-like patterned surfaces after 7 d in cultivation medium is 16% higher compared to the grit-blasted and acid-etched references. Finally, the possibility of patterning complex 3D dental implants is shown.