The enhancement of oral epithelial adhesion to the trans-mucosal material of dental implants may improve their long-term stability. The aim of this study is to investigate whether hydrothermal treatment with distilled water (HT-DW) applied to a Ti-6Al-4V (Ti64) alloy could improve epithelial cellular attachment. We hypothesized that this treatment would enhance the adsorption of proteins and the adhesion of gingival epithelial GE1 cells. This treatment changed the surface crystal structure into an anatase type of titanium oxide without an apparent change of surface roughness or topography. Nitrogen was not detected on the HT-DW-treated Ti64, which indicates decontamination. HT-DW-treated Ti64 exhibited a hydrophilic surface with a less than 10° angle of water contact. Adsorption of laminin-332 to the HT-DW-treated Ti64 was significantly greater than that of the untreated Ti64 plates (64). The number of GE1 cells on the HT-DW-treated Ti64 at 1 and 3 days was significantly lower than that on 64; however, cell adhesion strength on HT-DW was greater, with a higher expression of integrin β4, compared with 64. This indicates that the HT-DW treatment of Ti64 improves the integration of GE1 cells, which might facilitate the development of a soft tissue barrier around the implant.