Multi-Functional Surface Tailoring of SLM Ti-6Al-4V via Laser-Induced Surface Modification: Roughness Reduction, Chemical Stability, and Optical Appearance Control

This study investigates the effects of laser-induced surface modification on the physicochemical, electrochemical, and optical properties of Ti-6Al-4V (Ti64) dental abutments fabricated via selective laser melting (SLM). Although SLM-Ti64 offers excellent mechanical performance and biocompatibility, its inherent surface roughness, unstable passive layer, and dark metallic appearance present challenges for clinical applications requiring both surface precision and aesthetic integration. To address these challenges, a fiber laser was employed to selectively modify the surface without altering the bulk properties. The laser-modified SLM-Ti64 (L-SLM-Ti64) exhibited significantly reduced surface roughness, a chemically stable oxide layer with increased thickness, and enhanced scratch resistance. Potentiodynamic polarization testing revealed a 77% reduction in corrosion current density and suppression of metastable pitting. Post-corrosion characterization further confirmed minimal morphological degradation and preserved surface integrity in the L-SLM-Ti64 specimens. In addition, reflectance spectroscopy and CIE 1931 chromaticity analysis demonstrated that the L-SLM-Ti64 surface achieved optical characteristics closely matching those of commercial dental crowns, with a color difference (ΔE*ₐᵦ ≈ 0.33) falling below perceptibility thresholds. These results highlight the potential of laser-induced surface modification as an effective strategy for tailoring the multifunctional surface properties of SLM-Ti64, thereby enhancing its clinical applicability as a patient-specific dental abutment material.