How do the microbial profiles of periodontitis and peri-implantitis compare?

Correct answer: B. They are broadly similar — both are dominated by gram-negative anaerobes

• A. ❌ Candida can be recovered from some peri-implant sites, but peri-implantitis is not a fungal disease.
• B. ✅ CORRECT — Peri-implantitis lesions harbor essentially the same gram-negative anaerobic flora as periodontitis (P. gingivalis, T. forsythia, T. denticola, F. nucleatum, P. intermedia), which is exactly why an existing periodontitis patient is at higher risk for peri-implantitis. Peri-implant lesions do tend to include more staphylococci and enteric species, but the core profile overlaps.
• C. ❌ Aerobic gram-positive cocci dominate health, not disease.
• D. ❌ Peri-implantitis is a plaque-associated inflammatory condition with progressive bone loss — it is not sterile.

Note: Clinical consequence: treat and stabilize periodontitis BEFORE placing implants, and keep periodontitis patients on a tighter maintenance interval.