Basic study on suppression-effects of dental laser to bacterial biofilms

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The effects of Er:YAG laser on 4 single species (Enterococcus faecalis, Streptococcus mutans, Actinomyces viscosus. Propionibacterium acnes) biofilms formed on hydroxyapatite (HA) disks using modified Robbins Device was studied. The numbers of viable cells in S.mutans and A.viscosus biofilm were significantly reduced in all groups examined (20, 40, and 80 mJ radiation) compare to control groups. However, The number of P.acnes and E.faecalis cells were shown no significant differences in 20 mJ group. The biofilms of 3 bacterial species without P.acnes were morphologically changed, and the surface cells of the biofilms were flat.Porphyromonas gingivalis strain 381 biofilms were prepared on HA disks. At 0, 1, 3, and 7 days after perfusion of 3 antimicrobial agents, the antimicrobial effects by adenosine triphosphate (ATP) bioluminescence, and morphological investigation by scanning electron microscopy was performed. A significant decrease (p < 0.001) in ATP content was found between the c … More hlorhexidine-treated and control groups. The extracellular matrix structure and P.gingivalis cells were altered in the presence of chlorhexidine. Minocycline hydrochloride also caused a decrease in the ATP content and morphological change on P.gingivalis biofilms. Metronidazole showed no significant efficacy against P.gingivalis biofilms.The initial biofilm-forming ability of root canal isolates (E.faecalis, Streptococcus sanguis, Streptococcus intermedius, Streptococcus pyogenes, Staphylococcus aureus, Fusobacterium nucleatum, P.acnes, P.gingivalis and Prevotella intermedia) on gutta-percha points was investigated. Single species E.faecalis, S.sanguis, S.intermedius, S.pyogenes and S.aureus biofilms were generated on the surfaces of the specimens incubated in culture mediums supplemented with 45 or 90 v% serum. The E.faecalis and S.sanguis biofilms were significantly thicker than those of S.intermedius, S.pyogenes and S.aureus. No biofilms were detected on the specimens incubated with F.nucleatum, P.acnes, P.gingivalis, and P.intermedia. Less