title: Identification and localization of extraradicular biofilm-forming bacteria associated with refractory endodontic pathogens.
abstract: Bacterial biofilms have been found to develop on root surfaces outside the apical foramen and be associated with refractory periapical periodontitis. However, it is unknown which bacterial species form extraradicular biofilms. The present study aimed to investigate the identity and localization of bacteria in human extraradicular biofilms. Twenty extraradicular biofilms, used to identify bacteria using a PCR-based 16S rRNA gene assay, and seven root-tips, used to observe immunohistochemical localization of three selected bacterial species, were taken from 27 patients with refractory periapical periodontitis. Bacterial DNA was detected from 14 of the 20 samples, and 113 bacterial species were isolated. Fusobacterium nucleatum (14 of 14), Porphyromonas gingivalis (12 of 14), and Tannellera forsythensis (8 of 14) were frequently detected. Unidentified and uncultured bacterial DNA was also detected in 11 of the 14 samples in which DNA was detected. In the biofilms, P. gingivalis was immunohistochemically detected in all parts of the extraradicular biofilms. Positive reactions to anti-F. nucleatum and anti-T. forsythensis sera were found at specific portions of the biofilm. These findings suggested that P. gingivalis, T. forsythensis, and F. nucleatum were associated with extraradicular biofilm formation and refractory periapical periodontitis.
authors.affiliation: Department of Restorative Dentistry and Endodontology, Osaka University Graduate School of Dentistry, 1-8, Yamadaoka, Suita, Osaka 565-0871, Japan. noiri@dent.osaka-u.ac.jp.
authors.forename: Nobuo
authors.initials: N
authors.lastname: Noguchi
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Noiri
authors.forename: Masahiro
authors.initials: M
authors.lastname: Narimatsu
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Ebisu
mesh_terms: D000328:Adult; D000368:Aged; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000472:pathogenicity*; D018441:Biofilms; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D005260:Female; D005673:Fusobacterium / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000379:methods; D016966:Porphyromonas gingivalis / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity; D014076:Tooth Diseases / Q000382:microbiology* / Q000473:pathology
chemical_list: D004269:DNA, Bacterial