Bacteria most commonly found in periodontal pockets are:

Correct answer: D. Gram-negative anaerobes

• A. Gram-positive facultative anaerobes are early colonizers in plaque formation, not the primary pathogens in established periodontitis.
• B. Gram-positive aerobes (e.g., Streptococcus) dominate supragingival plaque and healthy gingival sulci, not diseased pockets.
• C. Gram-negative aerobes are not the primary inhabitants of anaerobic periodontal pockets.
• D. Correct. The subgingival microbiome of periodontal pockets is dominated by gram-negative anaerobic bacteria (e.g., Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola — the 'red complex'). The anaerobic environment of deep pockets favors these organisms.