The aim of this investigation was to examine the presence of 8 bacterial anaerobic species in endodontic samples from patients with primary and secondary infection. The association of clinical signs and symptoms with constituent species were also evaluated. Microbial samples were obtained from 72 teeth with primary endodontic infection and 35 teeth with secondary endodontic infection. DNA was extracted from samples and analyzed with a polymerase chain reaction (PCR)-based identification assay.

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... edical and dental histories were obtained from each patient. The prevalence of the targeted bacterial species was recorded for each case and descriptive statistical analyses were performed using the Pearson Chi-squared test. Nucleid acid amplification method (NAAM) analysis showed that all specimens were positive at least for 1 or more samples in primary and secondary infection teeth. The most frequently detected bacteria in all speciemens were Porphyromonas gingivalis, followed by Porphyromonas micros, Porphyromonas endodontalis, Fusobacterium nucleatum, Porphyromonas intermedia and Tannerella forsythia, respectively. The percentages of all selected bacteria found in primary infection group were higher than secondary infection group except for Porphyromonas intermedia. However, statistically significant difference was found only for T. forsythia and F. nucleatum which were higher percentage in primary infection than in secondary infection group. There was a significant association between tenderness to percussion and P. gingivalis (p < 0.05), pain with Porphyromonas melaninogenica (p < 0.05) and swelling with both P. gingivalis (p < 0.05) and P. melaninogenica (p < 0.05). Findings indicated that the prevalence of some species found in the primary infection group were higher than in the secondary infection group. In this study there was a significant association between tenderness to percussion and P. gingivalis, pain with P. melaninogenica and swelling with both P. gingivalis and P. melaninogenica.