Adhesion of Porphyromonas gingivalis strains to cultured epithelial cells from patients with a history of chronic adult periodontitis or from patients less susceptible to periodontitis

Background: The present study aimed to explain the interindividual variatio n in periodontitis susceptibility by differences in the initial adhesion ra te of Porphyromonas gingivalis to the pocket epithelium of these individual s, and/or by inter-P. gingivalis strain differences in association capacity (adhesion and internalization). Methods: Adhesion assays were performed on epithelial monolayers (cultured in vitro from pocket epithelium belonging to patients who were less or more susceptible to chronic adult periodontitis) using 11 genetically different clinical strains of P. gingivalis. Results: Both the disease category (less susceptible versus susceptible) an d the interstrain variation were found to have a significant effect (both P <0.05) on the initial bacterial association. The chronic adult periodontit is group showed significantly more association of P. gingivalis when compar ed to less susceptible patients (4.2 x 10(6) versus 3.5 x 10(6)). Also, the interstrain variation was significant, with strains Pg 4 and 5 representin g the least and best associating bacteria (1.8 x 10(6) colony forming units for Pg 4, 9 x 10(6) for Pg 5. Conclusions: These results indicate that periodontitis susceptibility is in fluenced by both the interindividual differences in pocket epithelium (allo wing more adhesion of P. gingivalis) or by the strain type by which the pat ient is infected (intra-species differences in adhesion capacity).