Fibrin Formation and Differentiation of Osteoblasts on TiO₂ Sol-gel-coated Discs

Objectives: Titanium is frequently used as dental implants because of its excellent biocompatibility and corrosion resistance.  These properties are based on its thin 2-8nm spontaneously titanium-oxide layers. However, its oxide-layers may cause some problems for clinical application due to relatively poor surface hardness, wear resistance and metal release. Sol-gel process is one of surface modification techniques that provide thicker TiO₂-layer than naturally occurred film, and subsequently improve tissue responses to implant surface. In this study, the thicker TiO₂ sol-gel-coated films were produced to improve fibrin formation and osteoblast functions.

Methods: TiO₂ sol-gel layers were produced on the cp-titanium discs. The characteristics of the TiO₂films and their effects on fibrin formation and human primary bone cells, in term of morphology, attachment, proliferation, differentiation and mineralization, were investigated.

Results: No significant difference in surface roughness was observed between titanium and TiO₂-coated discs. However, TiO₂ surface was more wettability than titanium discs. The XRD result of titanium discs show amorphous form whereas TiO₂-coated surface that show a rutile and anatase structure. TiO₂-coated surface has highest amount of fibrin scaffold than glass and titanium discs. In comparison to osteoblast grown on glass and titanium disc, the number of cells on the TiO₂ surface was significantly higher.  In addition, the expression of bone sialoprotein and osteocalcin mRNA was also higher on day-3 and 5, respectively.  ELISA analysis confirmed the increase of osteocalcin synthesis in cells grown on TiO₂.  Moreover, alizarin red staining showed that cells cultured on TiO₂-coated films contained higher amount of calcium deposition than those on Ti discs at day-20.

Conclusions: TiO₂ sol-gel-coated on titanium could enhance osteoblasts differentiation and promote mineralization. Thus, sol-gel-coated TiO₂ could be an effective protocol in promoting mineralization and improving osseointegration for dental implants.