New bacterial compositions in root-filled teeth with periradicular lesions.

The aim of this study was to isolate and detect microorganisms of root-filled teeth associated with periradicular lesions. Specimens were sampled from patients undergoing root canal retreatment. The bacteria were characterized by morphologic and biochemical analysis and by 16S rRNA gene sequencing. Microorganisms were detected in 10 of 18 teeth. The majority of positive samples revealed a mixed culture of 2-8 species. In 2 teeth Enterococcus faecalis was the only detected species. For the first time Vagococcus fluvialis was detected in root canals. Solobacterium moorei and Fusobacterium nucleatum were the most prevalent species. Presence of F. nucleatum was associated with the presence of S. moorei in 5 of 7 cases. In all teeth with Parvimonas micra and Dialister invisus, F. nucleatum and S. moorei were found. Moreover, members of additional different genera were detected delivering bacterial compositions that have been not described yet.