Objectives: To determine the percentage of persistant apical lesions positive for bacterial nucleic acids, to detect microorganisms difficult to cultivate in persistant apical lesions by PCR and relate them to endodontic failure, clinical symptoms and diabetes mellitus.
Materials and methods: The samples of persistent apical lesions were collected during apicoectomy. Bacterial ubiquitous primer 16S rRNA was used to detect 16S ribosomal RNA in 36 samples. A species-specific PCR was performed with primers targeted to the bacterial 16S rRNA genes of Prevotella Nigrescens, Pseudoramibacter alactolyticus, and Propionobacterium propionicum.
Results: Six samples (16.67%) were positive for bacterial ribosomal RNA. Pseudoramibacter alactolyticus was detected in three samples. Propionibacterium propionicum and Prevotella nigrescens were detected in one sample each. The prevalence of infection of such lesions with P. intermedia, P. propionicum and P. alactolyticus is low.
Conslusion: The study we conducted gave insufficient data about extraradicular infection and its connection with diabetes mellitus and clinical symptoms.
Conclusions: Apical lesions persisting after endodontic treatment could harbor microorganisms other than Actinomyces and Propionicum species.
Keywords: 16S Ribosomal RNA; Bacterial RNA; Polymerase Chain Reaction; Root Canal Preparation; Treatment Failure; periapical abscess.