Abstract
Apical periodontitis is an inflammatory disease of microbial etiology. It has been suggested that endodontic bacterial DNA might translocate to distant organs via blood vessels, but no studies have been conducted. We aimed first to explore overall extraradicular infection, as well as specifically by Porphyromonas spp; and their potential to translocate from infected root canals to blood through peripheral blood mononuclear cells. In this cross-sectional study, healthy individuals with and without a diagnosis of apical periodontitis with an associated apical lesion of endodontic origin (both, symptomatic and asymptomatic) were included. Apical lesions (N=64) were collected from volunteers with an indication of tooth extraction. Intracanal samples (N=39) and respective peripheral blood mononuclear cells from apical periodontitis (n=14) individuals with an indication of endodontic treatment, as well as from healthy individuals (n=14) were collected. The detection frequencies and loads (DNA copies/mg or DNA copies/μL) of total bacteria, Porphyromonas endodontalis and Porphyromonas gingivalis were measured by qPCR. In apical lesions, the detection frequencies (%) and median bacterial loads (DNA copies/mg) respectively were 70.8% and 4521.6 for total bacteria; 21.5% and 1789.7 for Porphyromonas endodontalis; and 18.4% and 1493.9 for Porphyromonas gingivalis. In intracanal exudates, the detection frequencies and median bacterial loads respectively were 100% and 21089.2 (DNA copies/μL) for total bacteria, 41% and 8263.9 for Porphyromonas endodontalis; and 20.5%, median 12538.9 for Porphyromonas gingivalis. Finally, bacteria were detected in all samples of peripheral blood mononuclear cells including apical periodontitis and healthy groups, though total bacterial loads (median DNA copies/μL) were significantly higher in apical periodontitis (953.6) compared to controls (300.7), p<0.05. Porphyromonas endodontalis was equally detected in both groups (50%), but its bacterial load tended to be higher in apical periodontitis (262.3) than controls (158.8), p>0.05; Porphyromonas gingivalis was not detected. Bacteria and specifically Porphyromonas spp. were frequently detected in endodontic canals and apical lesions. Also, total bacteria and Porphyromonas endodontalis DNA were detected in peripheral blood mononuclear cells, supporting their plausible role in bacterial systemic translocation.
Highlights
Apical periodontitis (AP) is the inflammatory destruction of the apical periodontium as the result of endodontic infection
A higher frequency of detection was identified for P. endodontalis in symptomatic apical lesion of endodontic origin (ALEO) compared to asymptomatic ALEOs (p = 0.003), while no significant differences were found in the detection frequencies of total bacteria and P. gingivalis or bacterial loads (p > 0.05)
Endodontic bacteria were detected in circulating mononuclear cells, whereas total bacterial loads were higher in peripheral blood mononuclear cells (PBMCs) from AP compared to healthy individuals
Summary
Apical periodontitis (AP) is the inflammatory destruction of the apical periodontium as the result of endodontic infection. AP can vary over time between two clinical entities, symptomatic and asymptomatic apical periodontitis (SAP and AAP, respectively), depending on the dynamic balance between bacterial consortia and the host’s response (Hsiao et al, 2012). Among them, the former is considered an immunologically exacerbated stage (Veloso et al, 2020). The endodontic pathogens organize in multispecies biofilm communities within the root canal, favoring the selection of Gram-negative anaerobic bacteria (Sakko et al, 2016). Though a substantial heterogeneity can be found among geographically diverse populations the blackpigmented anaerobes, Porphyromonas endodontalis and Porphyromonas gingivalis, are key pathogens in light of their high prevalence within the root canals, prominent virulence factors and/or significance in the bacterial community’s stability and virulence (Rôças and Siqueira, 2018)
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