Bacterial flora of dental periradicular lesions analyzed by the 454-pyrosequencing technology.

Introduction: Symptomatic teeth with periradicular lesions of infectious origin remain a significant challenge in dentistry, and the reason for the acute perturbation is incompletely understood. The present study used pyrosequencing of bacterial 16S ribosomal RNA (rRNA) genes to characterize the microbiota of periradicular lesions.

Methods: Thirteen periradicular lesions from 11 symptomatic and 2 asymptomatic teeth were sampled during apical surgery. Samples were subjected to DNA extraction and 16S rRNA polymerase chain reaction (PCR) amplification. PCR amplicons were then sequenced by using the Roche 454 GS FLX platform. Data were analyzed with the Quantitative Insights into Microbial Ecology (QIIME) software package.

Results: Seven of the 13 periradicular lesions (53.8%) yielded PCR amplicons, which generated 35,731 high-quality DNA sequences belonging to 10 bacterial phyla and 73 bacterial genera. All 7 lesions were associated with symptoms. The phyla with most bacterial taxa were Proteobacteria (proportion of total bacterial taxa, 33.3%), Firmicutes (30.9%), Actinobacteria (12.2%), and Bacteroidetes (11.4%). The most abundant genera were Fusobacterium (average of total sequences, 21.0%), Streptococcus (8.0%), Prevotella (7.5%), Corynebacterium (7.2%), Porphyromonas (6.0%). and Actinomyces (5.8%).

Conclusions: This study demonstrated that the microbiota of symptomatic periapical lesions is predominated by anaerobic bacteria but also contains substantial levels of streptococci, actinomyces, and bacteria not previously identified in the oral cavity. The etiopathogenic role and therapeutic implication of periradicular bacteria need to be determined.