“…However, the naturally formed titanium oxide film is not effective in improving the bioactivity of a titanium implant due to its small thickness. Therefore, oxide films need to be formed intentionally using various techniques such as thermal annealing (Feng Velten et al, 2002;Padma et al, 1988), chemical synthesis (Samuneva et al, 1993;Li and Kangasniemi, 1994), physical vapor deposition (Wu et al, 2006;Hsu et al, 1986), and anodic oxidation (Sul et al, 2002;Schreckenbach et al, 1999;Yang et al, 2004;de Sena et al, 2003).…”