Homogeneity and Heterogeneity of Microbiota among Intraradicular and Extraradicular Sites in Terms of Bacterial Composition in Teeth with Post-treatment Apical Periodontitis

Introduction : Post-treatment apical periodontitis (PoAP) represents an inflammatory condition of the periradicular tissue because of intracanal (re) infection after orthograde root canal treatment, whereas little is known about the etiological role of microbiota in PoAP. The purpose of this study was to investigate the diversity of microbiota among multiple intraradicular and extraradicular sites of a tooth associated with a PoAP lesion and to find out whether and how the diversity is related to several clinical parameters.