Multi-pronged study on actual state and suppression of bacterial biofilm associate with refractory periapical periodontal disease.

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We investigated the identification and localization of the bacteria in human extraradicular bolls. Extraradicular biofilms to identify bacteria using a PCR-based 16S rRNA gene assay, and to observe immunohistochemical localization of selected bacterial species were taken from patients with refractory periapical periodontitis. Fusobacterium nucleatum, Porphyromonas gingivalis, and Tannellera forsythensis were frequently detected. P.gingivalis were detected in all parts of the extraradicular biofilms. F.nucleatum were predominantly scattered at the middle layer, and T.forsythensis located at the superfacial layer in the biofilms.On the other hand, the control methods against single species biofilms of bacteria identified from the extraradicular biofilm were examined. P.gingivalis strain 381 biofilms were prepared using modified Robbins Device. Minocycline hydrochloride and Metronidazole, which showed effect against planktonic P.gingivalis cells, were not effective though chlorhexidine gl … More uconate were effective. Moreover, we found that the effects of Er.YAG laser against Enterococcus faecalis, Streptococcus mutans, Actinomyces viscosus and Propionibacterium acnes biofilms were different.We analyzed the gene associated with biofilm formation of P.gingivalis. A putative glycosyltransferase gene was isolated from P.gingivalis strain 381 and designated as gtfA. GtfA-deficient P.gingivalis lacked mature fimbriae morphologically and showed quite a low ability for autoaggregation, and its ability for attachment to epithelial cells was severely impaired. These results suggested that gtfA might regulate attachment ability in subgingival biofilms and act has a potent virulence factor.The initial biofilm-forming ability of root canal isolates on gutta-percha points was investigated. Enterococcus faecalis, Streptococcus sanguis, Streptococcus intermedius, Streptococcus pyogenes and Staphyrococcus aureus biofilms were generated on the surfaces of the specimens incubated in culture mediums supplemented with 45 or 90 v% serum. 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 Prevotella intermedia. Less