Current Perspectives on Additive Manufacturing and Titanium Surface Nanotopography in Bone Formation

Abstract

This study aimed to assess the impact of manufacturing methods (conventional and additive manufacturing) and surface treatments (polished and nanotopographic) on the physicochemical properties of Ti6Al4V alloy and their correlation with osteoblast cellular behavior. The evaluated groups were Machined Discs (MD), Machined Discs with Treatment (MD-WT), Additive-manufactured Discs (AD), and Additive-manufactured Discs with Treatment (AD-WT). Surface analyses included SEM, AFM, surface roughness, EDS, XRD, surface free energy, and zeta potential. MC3T3-E1 cells were cultured for biological assessments, including cell morphology, viability, gene expression, alkaline phosphatase activity, and mineralization. ANOVA and Holm-Sidak tests were applied (p < 0.05). MD exhibited grooved topography, AD had partially fused spherical particles, while MD-WT and AD-WT showed patterns from chemical treatment (H₃PO₄ + NaOH). EDS identified additional ions in MD-WT and AD-WT. XRD patterns indicated crystal lattice orientation differences. MD-WT and AD-WT displayed higher surface free energy than MD and AD (p < 0.05). AD had greater roughness (Sa 6.98 μm, p < 0.05). Biological analyses revealed higher cell viability for MD and AD (p < 0.001), higher ALP activity in MD, and lower in AD-WT. Gene expression varied, with MD showing higher Alpl, Ibsp, and Bglap (p < 0.001), and AD-WT showing higher Runx2 (p < 0.001). Mineralized matrix behavior was similar for MD, AD, and MD-WT (p > 0.05). MD and AD surfaces demonstrated superior osteogenic differentiation potential, while AD exhibited greater roughness, lower surface free energy, higher cell viability, and osteoblastic differentiation potential.