Susceptibility to various oral antiseptics of Porphyromonas gingivalis W83 within a Biofilm

The origin of chronic periodontal disease is strongly related to the nature and physiology of the subgingival bacterial biofilm, of which Porphyromonas gingivalis is a main protagonist. This study was conducted in vitro, to test the susceptibility of the W83 strain of P gingivalis to several oral antiseptics, bearing in mind its mode of growth as biofilm. To this end, the investigators inoculated a brain-heart infusion broth with Streptococcus gordonii, to which P gingivalis was added before perfusion for 7 d via a closed circuit containing a modified Robbins device. Then, various antiseptics were perfused through the circuit over 30 min, and their bactericidal effects were evaluated after culture by comparison of the mean proportion of bacteria killed. The average proportion of P gingivalis W83 killed after 15 min of contact with antiseptics was 90.51% (+/- 4.78) for chlorhexidine 0.2%, 89.87% (+/- 6.58) for povidone-iodine 1%, and 98.6% (+/- 0.86) for Listerine (R) (McNeil-PPC, Inc., Morris Plains, NJ). After 30 min of contact, survival of P gingivalis was nil, irrespective of the antimicrobial agent used. Preliminary results show that antiseptic mouth rinses, when used in pure concentrations in the traditional way, are effective in killing P gingivalis W83 within a biofilm. Furthermore, in light of these experiments, it appears that the best results are obtained when Listerine is used; however, new trials should be conducted to confirm this observation.