Bacterial diversity in persistent periapical lesions on root-filled teeth

Abstract

Background: The purpose of this study was to analyze the bacterial diversity in persistent apical lesions on root-filled teeth by using culture-independent molecular methods.

Design: Twenty surgically removed apical lesions from therapy-resistant teeth were examined for the presence of bacterial DNA using PCR targeting the 16s ribosomal RNA gene, followed by cloning and sequencing.

Results: Bacterial DNA was detected in 17 of the 20 samples (85%). A total of 236 clones were analyzed. Seven different bacterial phyla were represented and a total of 75 different bacterial taxa were identified; 36% of the species have not yet been cultivated. Commonly detected bacterial species included Fusobacterium spp., Prevotella spp., Tannerella forsythia, Porphyromonas endodontalis, Treponema denticola, Bacteroidetes spp., Peptostreptococcus spp., and Streptococcus spp.

Conclusions: A wide range of bacteria was identified in periapical lesions on therapy-resistant teeth. These bacteria may contribute in the etiology of periapical infection and impede healing of these lesions.

Keywords: 16s ribosomal RNA; bacterial phyla; endodontic infection; sequencing; therapy-resistant teeth.

Fig. 1

Apical surgery with a submarginal incision to avoid contamination of the surgical area.

Fig. 2

Phylogenetic tree of bacterial phylotypes detected in persistent periapical lesions. The marker bar represents a 5% difference in nucleotide sequences.