Total and Specific Bacterial Levels in the Apical Root Canal System of Teeth with Post-treatment Apical Periodontitis

By Antunes HS, Rôças IN, Alves FR, Siqueira JF Jr

Date: 04/2015
Journal: JOE


•Purpose: To evaluate the total bacterial counts and the presence, levels, and relative abundance of candidate endodontic pathogens exclusively in the apical root canal system associated with post-treatment apical periodontitis.


•Apical root specimens obtained during periradicular surgery of 27 adequately treated teeth with persistent apical periodontitis were cryogenically ground.

•DNA was extracted from the powder, and real-time polymerase chain reaction was used to quantify the total bacteria and 7 bacterial taxa.

•Most highlighted Results:

•Samples from 21 teeth were positive for bacteria.

•Streptococcus species were the most prevalent (76%) followed by members of the Actinobacteria phylum (52%) and Pseudoramibacter alactolyticus (19%).

•The mean total bacterial load in the apical root segments was 5.7  104 cell equivalents per root apex.

•Streptococci comprised from 0.02%–99.9% of the total bacterial counts, Actinobacteria from 0.02%–84.7%, and P. alactolyticus from 67.9%–99%.

•Although Enterococcus faecalis was found in only 3 (14%) cases, it was dominant in 2.

Clinical significance:

Streptococcus species, members of the Actinobacteria phylum, and P. alactolyticus were the most prevalent taxa in the apical canal system and dominated the bacterial populations in many cases of post-treatment apical periodontitis.