title: Apical root canal microbiota as determined by reverse-capture checkerboard analysis of cryogenically ground root samples from teeth with apical periodontitis.
abstract: BACKGROUND
  Bacteria located in the apical root canal system potentially participate in the pathogenesis of apical periodontitis. Detection and identification of apical bacteria can be compromised because of limitations in conventional sampling and identification procedures. This study identified several bacterial taxa in the apical and middle/coronal segments of primarily infected root canal system by using pulverized root segments and a culture-independent molecular method.
  
  
  METHODS
  Seventeen extracted teeth with attached apical periodontitis lesions were sectioned to obtain 2 root fragments (apical and middle/coronal segments). Root fragments were cryogenically ground, and DNA was extracted from samples. After multiple displacement amplification, DNA from samples was used as template in a reverse-capture checkerboard hybridization assay targeting 28 bacterial taxa.
  
  
  RESULTS
  Bacterial DNA was detected in all samples. The most prevalent taxa in the apical root canal system were Olsenella uli (76.5%), Prevotella baroniae (71%), Porphyromonas endodontalis (65%), Fusobacterium nucleatum (53%), and Tannerella forsythia (47%). O. uli, P. endodontalis, and Propionibacterium acnes were as frequently detected in apical samples as they were in middle/coronal samples. P. baroniae, T. forsythia, and F. nucleatum were found more frequently in the apical part of the canal as compared with matched coronal segments. Streptococcus species were more prevalent in middle/coronal samples. The median and mean of shared bacterial taxa between matched apical and middle/coronal segments were 27% and 41%, respectively.
  
  
  CONCLUSIONS
  Several candidate endodontic pathogens were very prevalent in the apical root canal system. The apical microbiota was usually complex and differed in species composition when compared with the microbiota of middle/coronal samples from the same tooth.
authors.affiliation: Department of Endodontics and Molecular Microbiology Laboratory, Estácio de Sá University, Rio de Janeiro, RJ, Brazil.
authors.forename: Isabela N
authors.initials: IN
authors.lastname: Rôças
authors.forename: Flávio R F
authors.initials: FR
authors.lastname: Alves
authors.forename: Adriana L
authors.initials: AL
authors.lastname: Santos
authors.forename: Alexandre S
authors.initials: AS
authors.lastname: Rosado
authors.forename: José F
authors.initials: JF
authors.lastname: Siqueira
mesh_terms: D015373:Bacterial Typing Techniques; D001439:Bacteroides / Q000302:isolation & purification; D015925:Cryopreservation; D004269:DNA, Bacterial / Q000032:analysis; D003786:Dental Pulp Cavity / Q000382:microbiology*; D016967:Fusobacterium nucleatum / Q000302:isolation & purification; D006801:Humans; D007778:Lactobacillus / Q000302:isolation & purification; D020411:Oligonucleotide Array Sequence Analysis; D010485:Periapical Periodontitis / Q000382:microbiology*; D016133:Polymerase Chain Reaction; D045202:Porphyromonas endodontalis / Q000302:isolation & purification; D018720:Prevotella / Q000302:isolation & purification; D012329:RNA, Bacterial / Q000032:analysis; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D019227:Tooth Apex / Q000382:microbiology*
chemical_list: D004269:DNA, Bacterial; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S