The main differences between supra and subgingival plaque as well as between health and disease were in the proportions and to some extent levels of Actinomyces, "orange" and "red" complex species.
Proportions of bacterial species differed markedly on different intraoral surfaces. The microbiota of saliva was most similar to that of the dorsal and lateral surfaces of the tongue. The microbiotas of the soft tissues resembled each other more than the microbiotas that colonized the teeth both above and below the gingival margin.
The data indicate that supragingival plaque can harbor putative periodontal pathogens, suggesting a possible rôle of this environment as a reservoir of such species for the spread or reinfection of subgingival sites.
This study explores a new approach for antimicrobial therapy with light activation of targeted poly-l-lysine (pL)–chlorine6 (c
e6
) conjugates. The goal was to test the hypothesis that these conjugates between pL and c
e6
would efficiently target photodestruction towards gram-positive (Actinomyces viscosus) and gram-negative (Porphyromonas gingivalis) oral species while sparing an oral epithelial cell line (HCPC-1). Conjugates of c
e6
with pL (average molecular weight, 2,000) having a positive, neutral, or negative charge were prepared. Illumination with red light (λmax = 671 nm) from a diode array produced a dose-dependent loss of CFU from the bacteria, under conditions that did not affect the viability of the epithelial cells. For P. gingivalis, the cationic conjugate produced 99% killing, while the neutral conjugate killed 91% and the anionic conjugate killed 76% after 1 min of incubation and exposure to red light for 10 min. For A. viscosus, the cationic conjugate produced >99.99% killing while HCPC-1 cells remained intact. The importance of the positive charge was shown by the effectiveness of c
e6
-monoethylenediamine monoamide (a monocationic derivative of c
e6
) in killing both bacteria. The clinically employed benzoporphyrin derivative under the same conditions killed epithelial cells while leaving P. gingivalis relatively unharmed. A mixture of c
e6
with pL did not show phototoxicity comparable with that of the cationic conjugate. These results were explained by the selective uptake of the conjugates by bacteria (20- to 100-fold) compared to that by mammalian cells, while free c
e6
showed much less selectivity for bacteria (5- to 20-fold). The data suggest that the cationic pL-c
e6
conjugate may have an application for the photodynamic therapy of periodontal disease.
Weekly professional supragingival plaque removal profoundly diminished counts of both supra- and subgingival species creating a microbial profile comparable to that observed in periodontal health. This profile was maintained at the final monitoring visit, 9 months after completion of therapy.
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