Periodontics · single question

The MAIN bacteria found in a healthy gingival sulcus are:

Aerobic, non-motile, gram-negative bacilli
Aerobic, non-motile, gram-positive cocci and bacilli (Streptococcus, Actinomyces)
Anaerobic, motile, gram-positive streptococci
Anaerobic, motile, gram-negative rods (these predominate in disease)

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Correct answer: B. Aerobic, non-motile, gram-positive cocci and bacilli (Streptococcus, Actinomyces)

A. Aerobic gram-negative species increase in gingivitis but are not dominant in health.
B. Correct. In health, the gingival sulcus is dominated by AEROBIC, NON-MOTILE, GRAM-POSITIVE organisms — primarily Streptococcus species and Actinomyces. These early colonizers form a compatible, low-pathogenicity plaque community.
C. Anaerobic gram-positive streptococci (Streptococcus anginosus group) exist in small numbers in health — they are NOT the primary bacteria.
D. Anaerobic motile gram-negative rods (Porphyromonas gingivalis, Treponema, Bacteroides) PREDOMINATE IN PERIODONTITIS — NOT in health.

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