Microbiota in the apical root canal system of tooth with apical periodontitis

摘要

Background: Apical periodontitis (AP) is essentially an inflammatory disease of microbial etiology primarily caused by infection ofthe pulp and root canal system. Variation ofthe bacterial communities caused by AP, as well as their changes respondingto dental therapy, are of utmost importance to understand the pathogensis ofthe apical periodontitis and establishing effective antimicrobial therapeutic strategies. This study aims to uncover the composition and diversity of microbiota associated to theroot apex to identify the relevant bacteria highly involved in AP, with the consideration of root apex samples from the infected teeth (with/without root canal treatment), healthy teeth as well as the healthy oral. Methods: Four groups of specimens areconsidered, the apical part of root from diseased teeth with and without root canal treatment, and wisdom teeth extracted to avoid being impacted (tooth healthy control), as well as an additional healthy oral control from biofilm of the buccal mucosa. DNA was extracted from these specimens and the microbiome was examined through focusing on the V3-V4 hypervariable region ofthe 16S rRNA gene using sequencing on lllumina MiSeq platform. Composition and diversity ofthe bacterial community were tested for individual samples, and between-group comparisons were done through differential analysis to identify the significant changes.Results: We observed reduced community richness gnd diversity in microbiota samples from diseased teeth compared to healthy controls: Through differential analysis between AP teeth and healthy teeth, we identified 49 OTUs significantly down-regulated aswell as 40 up-regulated OTUs for AP.Conclusion: This study provides a global view ofthe microbial community ofthe AP associated cohorts, and revealed that AP involved not only bacteria accumulated with a high abundance, but also those significantly reduced ones due to microbial infection.