Bacteria in the apical root canal of teeth with primary apical periodontitis.
OBJECTIVE
Bacteria settled in the apical root canal are in a privileged position to inflict damage to the periradicular tissues. Therefore, the species identified in this region can be of special relevance for the pathogenesis of apical periodontitis. This study investigated the occurrence and levels of several bacterial taxa in the apical root canal of teeth with apical periodontitis.


METHODS
DNA extracts from samples taken from the apical part of the root canal of extracted teeth evincing chronic apical periodontitis lesions served as templates for analysis of the presence and levels of 28 bacterial species/phylotypes using a 16S ribosomal RNA gene-based reverse-capture checkerboard hybridization assay.


RESULTS
Bacterial DNA was detected in 19 out of 20 samples. Detected taxa included Pseudoramibacter alactolyticus (32%), Bacteroidetes clone X083 (26%), Streptococcus species (21%), Olsenella uli (10.5%), Synergistes clone BA121 (10.5%), Fusobacterium nucleatum (10.5%), Porphyromonas endodontalis (10.5%), Dialister clone BS016 (5%), Filifactor alocis (5%), Parvimonas micra (5%), and Treponema denticola (5%). Of these, only Bacteroidetes clone X083 and Synergistes clone BA121 were found at levels above 10(5).


CONCLUSIONS
Occurrence of these bacterial taxa in the apical part of infected root canals indicates their potential pathogenetic role in the etiology of apical periodontitis.
Siqueira
José F
JF
Department of Endodontics, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, Brazil. jf_siqueira@yahoo.com
Rôças
Isabela N
IN
Alves
Flávio R F
FR
Silva
Marlei G
MG
D001421:Bacteria, Anaerobic / Q000302:isolation & purification*; D015373:Bacterial Typing Techniques; D004269:DNA, Bacterial / Q000032:analysis; D003786:Dental Pulp Cavity / Q000382:microbiology*; D003790:Dental Pulp Necrosis / Q000382:microbiology*; D006801:Humans; D009693:Nucleic Acid Hybridization; D010485:Periapical Periodontitis / Q000382:microbiology*; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D019227:Tooth Apex / Q000382:microbiology*
D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S