Adherence and hydrophobicity of invasive and noninvasive strains of Porphyromonas gingivalis.

The adherence of Porphyromonas gingivalis to cell surfaces of periodontal tissues may play an important role in its pathogenicity. In this study, 12 strains of P. gingivalis, including both invasive and noninvasive strains, were investigated for adherence to gingival ligament components. The test strains of P. gingivalis adhered to collagen, fibronectin, and laminin to significantly different degrees. An overall positive correlation was noted between hydrophobicity and the number of cells that attached to collagen coated on hydroxyapatite beads. Invasive strains had low hydrophobicity and bound less to collagen than did noninvasive strains that possessed strong hydrophobic properties. 3H-fimbriae extracted from P. gingivalis were found to attach to collagen-coated hydroxyapatite. The fimbriae extracted from noninvasive strains bound strongly to collagen, whereas invasive strains' fimbriae with low hydrophobicity bound weakly to collagen or saliva-coated hydroxyapatite. These data suggest that 1) fimbriae play an important role in colonization through their hydrophobic activity; 2) fimbriae of noninvasive strains are associated with the major adhesin for attachment to gingival tissue, whereas fimbriae of invasive strains are weakly involved in adherence; and 3) there is no correlation between colonization and the invasiveness of P. gingivalis.