Brunette et al. [9] discuss that the grooved surface changes the cytoplasm by offering a microenvironment and prepares a good condition for generating the calcifying tissue, and that cells which are arranged along the groove help the osteogenic cell differentiate to osteoblast (Fig. 3.6). Further, vinculins, which is one of the proteins of attaching to the substrate, are also oriented to the microgroove (Fig. 3.7). To support cellular attachment, spreading and growth, and improve cellular function, a lot of reports have been published about roughened implant surfaces (Fig. 3.8) [10–13], as well as on controlled microtopography [9, 13–19]. We also explored how the fibroblast originated from human gingiva reacts against the titanium discs of various surface geometries. In the phase-contrast microscopic view of titanium disc with mechanically polished grooves on the surface, it is observed that cells are surrounding the disc. In the scanning electron microscopic view, cells are arranged along the groove (Contact guidance (Fig. 3.9) [10]. On the other hand, in the phase-contrast microscopic view of titanium disc with rough surface, cells are arranged vertically to disc. In the scanning electron microscopic view, cells are arranged in free directions to disc, and cell bridge is geometryed (Two center effect: Fig. 3.10) [10].

Surface chemistry involves the adsorption of proteins and cells on biomaterials. This adsorption reflects the affinity between two substances, and the strength of adsorption follows the order: chemical adsorption including covalent bonds and ionic bonds > electrostatic force found in electrokinetic potential or zeta potential > hydrogen bonds involved in hydrophilic groups such as –OH, –COOH, and –NH₂ > hydrophobic interaction (i.e., adsorption of hydrophobic substances in water) > van der Waals forces. Adsorption characteristics are primarily evaluated by hydrophobicity (wettability), which can be determined by measuring the surface energy (contact angle), and electrokinetic potential (zeta potential, isoelectric point), which reflects surface electric charges and these affect creation of firm integration between implant and cells.

As for the surface chemistry, methods of modifying the titanium surface using adhesive proteins such as osteonectin, fibronectin or laminin-5 compatible with the soft tissue/implant interface have been proposed. For the implant surface in contact with subepithelial connective tissues, tresyl chloride treatment is used to adhere the selected proteins such as fibronectin to the amino residues [20]. Thus the gingival epithelium attached to dental implants through the formation of hemidesmosomes using laminin-5 [21]. However, a stable coating and prevention of protein denaturation at the time of implantation are necessary using motif-programming or plasma treatment.