Evaluation of in vitro and in vivo tests for Surface-Modified Titanium by H2SO4 and H2O2 Treatment

Titanium is widely used as an implant material for artificial teeth. Furthermore, various studies have examined surface treatment with respect to the formation of a fine passive film on the surface of commercial titanium and its alloys and to improve the bioactivity with bone. However, there is insufficient data about the biocompatibility of implant materials in the body. The purpose of this study was to examine whether surface modification affects the precipitation of apatite on titanium metal. Specimens were chemically washed for 2 min in a 1:1:1.5 (vol.%) mixture of 48 %HF, 60 %HNO3 and distilled water. The specimens were then chemically treated with a solution containing 97 %H2SO4 and 30 %H2O2 at the ratio of 1:1 (vol.%) at 40℃ for 1 h, and subsequently heat-treated at 400℃ for 1 h. All the specimens were immersed in HBSS with pH 7.4 at 36.5℃ for 15 d, and the surface was examined with TF-XRD, SEM, EDX and XPS. In addition, specimens of commercial pure Ti, with and without surface treatment, were implanted in the abdominal connective tissue of mice for 28 d. Conventional aluminum and stainless steel 316L were also implanted for comparison. An amorphous titania gel layer was formed on the titanium surface after the titanium specimen was treated with a solution of H2SO4 and H2O2. The average roughness was 2.175 um after chemical surface treatment. The amorphous titania was subsequently transformed into anatase by heat treatment at 400℃ for 1 h. The average thickness of the fibrous capsule surrounding the specimens implanted in the connective tissue was 47.1 um in the chemically treated Ti, and 52.2, 168.7 and 101.9 um, respectively, in the untreated commercial pure Ti, aluminum and stainless steel 316L.