In vitro characterization of primary osteoblasts on titanium surfaces processed with wire-type electric discharge...

The fixation of titanium implants in bone tissue is affected by the presence of a passive titanium oxide (TiO₂) layer. Specifically, oxidation products in the amorphous TiO₂ matrix enhance the mechanical properties of mineralized tissues. In addition, in vitro mineralization mediated by primary osteoblasts on amorphous TiO₂ generates stiff tissues in a process that resembles pathological mechanisms connected with tumors and proceeds through hydrogen peroxide-inducible clone-5 (Hic-5) expression. However, the relationship between surface-based peroxidation and stiff mineralized tissue formation remains unclear. In this study, titanium samples were processed using wire electrical discharge machining to generate oxidation products in amorphous TiO₂. The gene expression profiles of primary osteoblasts cultured on these specimens were characterized. Increased expression of Hic-5 was correlated with the presence of peroxidation products. The crystallization of amorphous TiO₂ in these samples reduced the expression of both Hic-5 and lysyl oxidase, an enzyme that promotes matrix cross-linking.