title: Bacterial invasion into radicular dentine-an in vitro study.
abstract: OBJECTIVE
  We wanted to investigate differences in invasiveness into radicular dentinal tubules by monocultured and co-cultured bacteria frequently found in infected root canals.
  
  
  METHODS
  Fifty-one human roots were incubated for 8 weeks with monocultured Streptococcus gordonii ATCC 10558, Streptococcus sanguinis ATCC 10556, and with five capnophiles/anaerobes as well as with capnophiles/anaerobes co-cultured with a streptococcal species. Thereafter, bacterial samples were cultured from the inner, middle, and outer third of the root dentine of longitudinally broken teeth (n = 5). In addition, scanning electron microscopy (SEM) images were obtained.
  
  
  RESULTS
  Single gram-positive species were able to penetrate into the middle and outer third of the root dentine. Fusobacterium nucleatum ATCC 25586 was not found in any of the dentine specimens. Prevotella intermedia ATCC 25611 and Porphyromonas gingivalis ATCC 33277 were found in the inner and middle third. The bacterial load of streptococci was higher in all thirds in co-cultures compared to single infections. In co-cultures with streptococci, Actinomyces oris ATCC 43146 was found in the outer third in 9/10 samples, whereas P. intermedia ATCC 25611 was not detectable inside dentine. Co-culture with S. sanguinis ATCC 10556 enabled F. nucleatum ATCC 25586 to invade dentine; SEM images showed that F. nucleatum ATCC 25586 had a swollen shape.
  
  
  CONCLUSIONS
  Invasiveness of bacteria into dentinal tubules is species-specific and may change depending on culturing as a single species or co-culturing with other bacteria.
  
  
  CONCLUSIONS
  Oral streptococci may promote or inhibit invasion of capnophiles/anaerobes into radicular dentine.
authors.affiliation: Department of Preventive, Restorative and Pediatric Dentistry, University of Bern, Freiburgstrasse 7, CH-3010, Bern, Switzerland.
authors.forename: Simone
authors.initials: S
authors.lastname: Stauffacher
authors.affiliation: Department of Preventive, Restorative and Pediatric Dentistry, University of Bern, Freiburgstrasse 7, CH-3010, Bern, Switzerland.
authors.forename: Adrian
authors.initials: A
authors.lastname: Lussi
authors.affiliation: Center of Electron Microscopy, University Hospital of Jena, Jena, Germany.
authors.forename: Sandor
authors.initials: S
authors.lastname: Nietzsche
authors.affiliation: Department of Preventive, Restorative and Pediatric Dentistry, University of Bern, Freiburgstrasse 7, CH-3010, Bern, Switzerland. klaus.neuhaus@zmk.unibe.ch.
authors.forename: Klaus W
authors.initials: KW
authors.lastname: Neuhaus
authors.affiliation: Laboratory of Oral Microbiology, Department of Periodontology, University of Bern, Bern, Switzerland.
authors.forename: Sigrun
authors.initials: S
authors.lastname: Eick
mesh_terms: D000190:Actinomyces / Q000302:isolation & purification; D058491:Bacterial Load; D018920:Coculture Techniques; D003786:Dental Pulp Cavity / Q000382:microbiology*; D003804:Dentin / Q000382:microbiology*; D016967:Fusobacterium nucleatum / Q000302:isolation & purification; D006801:Humans; D066298:In Vitro Techniques; D008855:Microscopy, Electron, Scanning; D016966:Porphyromonas gingivalis / Q000302:isolation & purification; D018713:Prevotella intermedia / Q000302:isolation & purification; D013045:Species Specificity; D054773:Streptococcus gordonii / Q000302:isolation & purification; D013298:Streptococcus sanguis / Q000302:isolation & purification
keywords: Bacterial invasion; Co-culture; Dentinal tubules; Monoculture; Root dentine; Scanning electron microscopy