What is the most common bacterial flora found in root canal infections of necrotic teeth?

Root canal infections of necrotic teeth are predominantly polymicrobial, with gram-negative obligate anaerobes constituting the majority of the bacteria. The most commonly isolated species include Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum, and Treponema denticola. These organisms thrive in the anaerobic environment of the necrotic pulp space. The proportion of obligate anaerobes increases as the infection becomes more established. In contrast, early pulpitis may involve facultative anaerobes. Understanding the microbial profile guides antibiotic selection; amoxicillin and metronidazole combinations effectively target both facultative and obligate anaerobes.