Identification of oral spirochetes at the species-level and their association with other bacteria in endodontic infections.

OBJECTIVES: Recent molecular approaches have revealed that fastidious organisms such as Bacteroides forsythus and oral treponemes were frequently found in root canals with apical periodontitis. The purpose of this study was to identify the isolates of oral spirochetes at the species level in endodontic infections and to determine their association with B forsythus and Porphyromonas gingivalis. STUDY DESIGN: Seventy-nine teeth with apical periodontitis were selected for this study. After sampling from the root canals aseptically, polymerase chain reaction amplification for the 16S rRNA gene was performed with eubacterial universal primers. Subsequently, dot-blot hybridization was performed with 8 species-specific oligonucleotide probes. The microbial associations were analyzed by using the odds ratio. RESULTS: The most frequently found species was P gingivalis (27.4%), followed by Treponema maltophilum (26%), B forsythus (16.4%), and Treponema socranskii (2.7%). Other treponemes, including Treponema denticola, were not detected in our samples. Significant microbial associations were identified between T maltophilum, B forsythus, and P gingivalis by performing analysis with the odds ratio. CONCLUSION: Our results indicate that T maltophilum should be included in etiologic studies of endodontic diseases.ope