Bacterial Viability in Persistent Apical Periodontitis: A Systematic Review.

Introduction: Apical inflammatory lesions are a response to microbial infections. However, their persistence despite adequate clinical and radiographic conditions remains incompletely understood. This systematic review aimed to analyze the evidence regarding the presence of viable microorganisms in cases of persistent apical periodontitis.

Methods: A search was conducted in MEDLINE/PubMed, EMBASE, Scopus, Web of Science, The Cochrane Library, the CAPES Bank of Theses and Dissertations, and gray Literature. Restrictive inclusion criteria were applied, limiting the selection to studies in which periapical tissue samples were obtained during apical surgery. The quality of the included studies was assessed using a Joanna Briggs Institute Checklist.

Results: The search yielded 522 studies, and 4 were selected for full analysis. The main finding of this review indicated the presence of viable microorganisms in persistent apical periodontitis. One study demonstrated bacterial viability through cell culture, while 3 others used RNA-based methods. The studies employing RNA analysis showed methodological heterogeneity. It was also noted that infections associated with persistent apical periodontitis are characterized by a diversity of microorganisms.

Conclusions: The evidence presented in this review suggests the presence of viable bacteria in persistent apical periodontitis. However, it remains unclear whether the persistence of the lesion is due to viable bacteria within the lesion itself, microorganisms located intra- and extraradicular surfaces, or a combination of both.