IADR Abstract Archives
Gram-Negative Bacteria of Clinical Relevance in Endodontic Failure
Objectives: One of the causes of endodontic treatment failure is the secondary/persistent infection, being Fusobacterium nucleatum one of the most of the Gram-negative strict anaerobic bacteria found in these cases. F. nucleatum has been shown to promote the secretion of pro-inflammatory cytokines and metalloproteinases, cells closely associated with apical bone resorption, characteristic of post-treatment infection. The aim of this work was to study in cases of endodontic failure: a) the root canal microbiota constitution; b) the prevalence of F. nucleatum; c) the correlation of the microorganisms with the patients' signs and symptoms.
Methods: Microbial samples were collected from 15 teeth with post-treatment apical periodontitis and the need for endodontic retreatment. After the bacterial DNA extraction, Nested-PCR was carried out with species-specific primers for 13 species, including bacteria of difficult cultivation. Pearson's Chi-square test was used to test the null hypothesis that there is no association between bacterial species and clinical signs and symptoms (p <0.05).
Results: The results indicated a mixed microbiota with the presence of Gram-positives (51.7%) and Gram-negatives (48.3%), strict-(67.8%) and facultative- (32.2%) anaerobes, cocci (41.5%) and bacilli (58.5%) bacteria. The most prevalent species were Enterococcus faecalis (93.3%), Fusobacterium nucleatum (93.3%), Streptococcus sobrinus (86.6%) and Actinomyces israelii (80%). Only two correlations were found, both negatives, between pain and the number of facultative anaerobic bacteria; and between periapical radiolucency equal to or smaller than 2 mm and facultative anaerobic bacteria (p<0.05).
Conclusions: It was concluded that the microbiota of the secondary/persistent infection is heterogeneous and that Nested-PCR has proved to be efficient in the detection of bacteria, including those of difficult cultivation. Fusobacterium nucleatum was frequently detected in the root canals and might play an important role in the development of apical periodontitis.
Methods: Microbial samples were collected from 15 teeth with post-treatment apical periodontitis and the need for endodontic retreatment. After the bacterial DNA extraction, Nested-PCR was carried out with species-specific primers for 13 species, including bacteria of difficult cultivation. Pearson's Chi-square test was used to test the null hypothesis that there is no association between bacterial species and clinical signs and symptoms (p <0.05).
Results: The results indicated a mixed microbiota with the presence of Gram-positives (51.7%) and Gram-negatives (48.3%), strict-(67.8%) and facultative- (32.2%) anaerobes, cocci (41.5%) and bacilli (58.5%) bacteria. The most prevalent species were Enterococcus faecalis (93.3%), Fusobacterium nucleatum (93.3%), Streptococcus sobrinus (86.6%) and Actinomyces israelii (80%). Only two correlations were found, both negatives, between pain and the number of facultative anaerobic bacteria; and between periapical radiolucency equal to or smaller than 2 mm and facultative anaerobic bacteria (p<0.05).
Conclusions: It was concluded that the microbiota of the secondary/persistent infection is heterogeneous and that Nested-PCR has proved to be efficient in the detection of bacteria, including those of difficult cultivation. Fusobacterium nucleatum was frequently detected in the root canals and might play an important role in the development of apical periodontitis.