Human Osteoblast Behavior on Titanium Implant Surface Coating with Sintered Hydroxyapatite

Abstract

Osseointegration is strongly influenced by the physical and chemical characteristics of the implant surfaces, namely topography, roughness profile, and biofunctionalization. The current research assessed the influence of laser surface texturing and hydroxyapatite (HA) biofunctionalization on the viability, morphology, and inflammatory profile of human osteoblasts. Ti-6Al-4V disks were mechanically polished or laser-textured using an Nd:YVO4 laser to generate checkerboard patterns with spatial periodicities of 0.25 or 0.8 mm. Textured surfaces were subsequently coated with nanohydroxyapatite and sintered using either conventional furnace or CO2 laser sintering. The immortalized human osteoblastic line (hFOB 1.19) was seeded onto seven experimental surfaces for up to 14 days. Cell viability was assessed by a resazurin-based assay, while cellular attachment and morphological features were examined using scanning electron microscopy. Additionally, release levels of IL-1β, IL-8, and IL-10 were quantified by ELISA. Smooth titanium exhibited higher osteoblast viability than textured surfaces, whereas the 0.25 mm pattern generally performed better than the 0.8 mm pattern. HA biofunctionalization consistently improved viability within both texture patterns, irrespective of the sintering method, while the sintering technique itself had no significant effect. The 0.8 mm pattern showed lower IL-1β secretion, whereas IL-10 remained largely unchanged. Considering the inherent bounds of this in vitro study, smooth titanium surfaces exhibited the highest osteoblast viability, whereas the 0.25 mm pattern overall induced a more favorable cellular response compared to the 0.8 mm pattern. Hydroxyapatite biofunctionalization improved cell viability, whereas no consistent differences were observed between conventional and laser sintering.