title: Microbial diversity in persistent root canal infections investigated by checkerboard DNA-DNA hybridization.
abstract: BACKGROUND
  The aim of the present study was to investigate the composition of the root canal microbiota in endodontic failures in order to identify and quantify these microorganisms.
  
  
  METHODS
  Microbiological samples were taken from 36 root canals with persistent endodontic infection. The presence, levels, and proportions of 79 bacterial species were determined by checkerboard DNA-DNA hybridization. The Pearson correlation coefficient was used to investigate the relations between bacterial counts and clinical conditions (P ≤ .05).
  
  
  RESULTS
  Enterococcus faecium (36%), Streptococcus epidermidis (36%), Eubacterium saburreum (28%), Parvimonas micra (28%), Streptococcus sanguis (28%), Capnocytophaga sputigena (28%), Leptotrichia buccalis (28%), Enterococcus faecalis (28%), and Staphylococcus warneri (28%) were the most prevalent species; and there was a low prevalence of Treponema socranskii (3%), Fusobacterium periodonticum (3%), Capnocytophaga gingivalis (3%), and Spiroplasma ixodetis (3%). The highest mean levels were found for the following species: E. faecium, Dialister pneumosintes, Staphylococcus epidermidis and Helicobacter pylori. There was a statistically significant difference between the levels of gram-negative species and gram-positive species (13.5 × 10(5) vs 6.5 × 10(5), respectively). A positive correlation was found between the area of the periapical lesion and the levels of gram-negative and rod species (P < .05).
  
  
  CONCLUSIONS
  The microbiota from teeth with persistent apical periodontitis presents a mixed and complex profile, hosting E. faecium and S. epidermidis as the most highly prevalent species. No correlation was found between any of the species tested and clinical findings; however, periapical lesions with the largest areas presented higher counts of gram-negative and rod species.
authors.affiliation: Proclin Department, School of Dentistry, Rio de Janeiro State University, Rio de Janeiro, Brazil.
authors.forename: C F
authors.initials: CF
authors.lastname: Murad
authors.affiliation: Proclin Department, School of Dentistry, Rio de Janeiro State University, Rio de Janeiro, Brazil. Electronic address: lsassone@uerj.br.
authors.forename: L M
authors.initials: LM
authors.lastname: Sassone
authors.affiliation: Department of Periodontology, Dental Research Division, Guarulhos University, São Paulo, Brazil.
authors.forename: M
authors.initials: M
authors.lastname: Faveri
authors.affiliation: Microbiology, Immunology and Parasitology Department, School of Medical Science, Rio de Janeiro State University, Rio de Janeiro, Brazil.
authors.forename: R
authors.initials: R
authors.lastname: Hirata
authors.affiliation: Department of Periodontology, Dental Research Division, Guarulhos University, São Paulo, Brazil.
authors.forename: L
authors.initials: L
authors.lastname: Figueiredo
authors.affiliation: Department of Periodontology, Dental Research Division, Guarulhos University, São Paulo, Brazil.
authors.forename: M
authors.initials: M
authors.lastname: Feres
mesh_terms: D000328:Adult; D000368:Aged; D002206:Capnocytophaga / Q000302:isolation & purification; D004269:DNA, Bacterial / Q000032:analysis*; D003786:Dental Pulp Cavity / Q000382:microbiology*; D013293:Enterococcus faecalis / Q000302:isolation & purification; D016984:Enterococcus faecium / Q000302:isolation & purification; D005051:Eubacterium / Q000302:isolation & purification; D005260:Female; D045825:Fusobacteriaceae Infections / Q000382:microbiology; D016965:Gram-Negative Anaerobic Straight, Curved, and Helical Rods / Q000302:isolation & purification; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology; D016908:Gram-Positive Bacterial Infections / Q000382:microbiology; D016481:Helicobacter Infections / Q000382:microbiology; D016480:Helicobacter pylori / Q000302:isolation & purification; D006801:Humans; D045183:Leptotrichia / Q000302:isolation & purification; D008297:Male; D064307:Microbiota; D008875:Middle Aged; D009693:Nucleic Acid Hybridization / Q000379:methods; D010462:Peptostreptococcus / Q000302:isolation & purification; D010483:Periapical Diseases / Q000382:microbiology; D010485:Periapical Periodontitis / Q000382:microbiology*; D013203:Staphylococcal Infections / Q000382:microbiology; D013212:Staphylococcus epidermidis / Q000302:isolation & purification; D013290:Streptococcal Infections / Q000382:microbiology; D013298:Streptococcus sanguis / Q000302:isolation & purification; D019553:Tooth, Nonvital / Q000382:microbiology*
chemical_list: D004269:DNA, Bacterial
keywords: Apical periodontitis; bacteria; checkerboard DNA-DNA hybridization; persistent infection