To propose a mechanism for apical epithelialization at the implant-tissue interface, cell contact to titanium surfaces and adhesive strength of epithelial-like (HGE) and fibroblastic (HGF) cells derived from human gingiva were investigated under three different media conditions containing plaque extracts: nonfiltered, 5-µm pore filtered, and 0.22-µm pore filtered. The plaque extracts had a greater effect in decreasing the growth rate of the HGF than of the HGE. Similarly, the HGE exhibited greater adhesive strength than the HGF. These differences in the cells resistance to plaque extracts were also observed using light and electron microscopy. Evidence from this study suggests that the difference in growth, contact, and adhesive strength of the HGE and HGF cells to titanium surfaces may promote apical epithelialization under the pathologic condition. Keywords: biologic seal, cell culture, epithelialization, plaque extracts