The apical root canal system of teeth with posttreatment apical periodontitis: correlating microbiologic, tomographic and histopathologic findings

2020 
Introduction This study evaluated the microbiological conditions of the apical root canal system of teeth with posttreatment apical periodontitis and correlated them with observations from cone-beam computed tomography (CBCT), micro-computed tomography (micro-CT) and histopathology. Methods Root apices were obtained from 36 root canal-treated teeth subjected to perirradicular surgery. CBCT exam was available before surgery. The apical root specimens were scanned in a micro-CT device and then cryopulverized. The powder was subjected to DNA extraction for real-time polymerase chain reaction quantification of total bacteria, Streptococcus species, members of the phylum Actinobacteria, and Enterococcus faecalis. Microbiological findings were evaluated for associations with CBCT, micro-CT and histopathologic data. An association between lesion size and the proportion of unfilled apical canal system volume was also assessed. Results All cryopulverized specimens were positive for total bacteria. Actinobacteria and streptococci occurred in 35 and 33 specimens, respectively, and were usually dominant in the community. Actinobacteria counts were 2.23 times higher in granulomas than in cysts. Streptococcus were significantly more present in small lesion cases. E. faecalis was detected in only 7 samples, always as a dominant community member. Association of total bacteria, streptococci and Actinobacteria counts with the unfilled canal volume was significant in the univariate analyses, but not confirmed in the adjusted analyses. Large lesions were significantly associated with a higher volume of unfilled apical canal. Conclusions Bacterial infection occurred in all root apices, with high prevalence and dominance of Actinobacteria and streptococci. The volume of unfilled apical canal system was significantly associated with the lesion size and possibly with bacterial counts. Findings illustrate the need to thoroughly disinfect and fill the apical root canal of infected teeth during endodontic therapy.
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