In vitro and in vivo evaluation of surface functionalization of titanium with H₂ O₂ hydrothermal treatment and FGF-2

The goals of the study were to investigate the effects on bone bioactivity of a titanium dioxide layer formed by hydrothermal oxidation of a titanium surface with hydrogen peroxide (H₂ O₂ ) and loading with fibroblast growth factor-2 (FGF-2) in vitro and in vivo. Ti-6Al-4V discs were hydrothermally oxidized with H₂ O₂ and then loaded with FGF-2. After cytotoxicity testing, Ti-6Al-4V mini-implants were subjected to the same treatment, and their osteogenic potential was evaluated histologically in a rat model. H₂ O₂ hydrothermal oxidation resulted in a dense porous network structure and hydrophilic changes, which improved retention of FGF-2. Morphologically, the cell density was higher, cell elongation was more pronounced, and the cell adhesion area was significantly higher in FGF-2-loaded cells than in those without FGF-2. In a cell proliferation assay using mouse osteoblast-like cells, absorbance tended to increase over time, especially in the FGF-2 group after 7 and 14 days, and in a bone differentiation assay based on ALP activity, there was a significant increase in the FGF-2 group after 14 days. In the rat model, H₂ O₂ hydrothermal oxidation and FGF-2 loading both resulted in more laminar bone tissue in the bone marrow around the mini-implant. These results suggest that titanium surface functionalization by H₂ O₂ hydrothermal oxidation and FGF-2 may promote initial cell adhesion, proliferation, and osteodifferentiation, and enhance bone bioactivity. These effects all contribute to early bonding of an implant with the surrounding bone.