title: Visualization of initial bacterial colonization on dentine and enamel in situ.
abstract: Bacterial colonization of dentine is of high relevance in cariology, endodontology and periodontology. The aim of the present in situ study was to establish recent methods for visualization and quantification of initial bacterial adherence to dentine in comparison to enamel. For this purpose, bovine enamel and dentine slabs were fixed on buccal sites of individual upper jaw splints worn by 6 subjects for 30min, 120min and 360min, respectively. Adherent bacteria on the slabs were visualized and quantified with DAPI-staining (4',6-diamidino-2-phenylindole) and fluorescence in situ hybridization (FISH) of streptococci and eubacteria using the CLSM (confocal laser scanning microscopy) as well as an epifluorescence microscope. In addition, the number of colony forming units was quantified after desorption. Representative samples were processed for SEM (scanning electron microscopy) and TEM (transmission electron microscopy). All methods clearly indicated that a significantly higher number of bacteria adhered to dentine than to enamel. Furthermore, the amount of bacteria on the dentine increased with increasing oral exposure time, but remained rather constant on the enamel. The CLSM allowed visualization of bacteria in the dentinal tubules. Bacteria were found preferentially at the openings of the dentine tubules, but were distributed randomly on the enamel. In conclusion, the adopted methods are suitable for visualization and quantification of bacterial adhesion to dentine. Even the initial bacterial colonization of dentine is much more pronounced than bacterial adherence to the enamel.
authors.affiliation: Department of Operative Dentistry and Periodontology, University of Freiburg, Hugstetter Str. 55, D-79106 Freiburg, Germany.
authors.forename: David Jonathan
authors.initials: DJ
authors.lastname: Jung
authors.forename: Ali
authors.initials: A
authors.lastname: Al-Ahmad
authors.forename: Marie
authors.initials: M
authors.lastname: Follo
authors.forename: Bettina
authors.initials: B
authors.lastname: Spitzmüller
authors.forename: Wiebke
authors.initials: W
authors.lastname: Hoth-Hannig
authors.forename: Matthias
authors.initials: M
authors.lastname: Hannig
authors.forename: Christian
authors.initials: C
authors.lastname: Hannig
mesh_terms: D000818:Animals; D001419:Bacteria / Q000254:growth & development*; D001422:Bacterial Adhesion; D018407:Bacterial Physiological Phenomena; D002417:Cattle; D003743:Dental Enamel / Q000382:microbiology*; D003804:Dentin / Q000382:microbiology*; D005456:Fluorescent Dyes / Q000494:pharmacology; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000379:methods; D007211:Indoles / Q000494:pharmacology; D008855:Microscopy, Electron, Scanning; D013194:Staining and Labeling / Q000379:methods; D013997:Time Factors
chemical_list: D005456:Fluorescent Dyes; D007211:Indoles; C007293:DAPI