SEM micrographs. The fine group specimens had a relatively featureless surface compared to the coarse group specimens. Fine group: Oxinium (a), Co-Cr-Mo (b), Ti-6Al-4 V (c), Cp-Ti (d), SUS316L (e). Coarse group: Oxinium (f), Co-Cr-Mo (g), Ti-6Al-4 V (h), Cp-Ti (i), SUS316L (j). Original magnification × 5000 (Scale bar =1 μm).