Periodontitis RA Link — SCE Rheumatology MCQ
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Correct answer: D — Porphyromonas gingivalis expresses PPAD, providing a plausible citrullination mechanism; periodontitis is associated with rheumatoid arthritis activity, and treatment may yield short-term improvement, although certainty is low.
Explanation lettering: C = shown as B · D = shown as C · B = shown as D
B is correct. Porphyromonas gingivalis expresses peptidylarginine deiminase (PPAD), which can citrullinate bacterial and host proteins and therefore provides a biologically plausible route to RA-relevant loss of tolerance. Epidemiological studies support an association between periodontitis and RA, including greater RA disease activity, but do not prove that periodontitis causes RA. Periodontal treatment may produce modest short-term improvements in DAS28, although certainty is limited by small studies, heterogeneity and risk of bias. RA does not simply cause all periodontal disease (A), and smoking is an important confounder rather than a complete explanation (C). P. gingivalis does possess a citrullinating enzyme (D). Periodontal care is appropriate for periodontal health and may be a useful adjunct, but it is not an established DMARD and must not replace evidence-based RA treatment escalation (E).
Reference: Periodontitis and Rheumatoid Arthritis: Shared Pathophysiology, Bidirectional Association, and Therapeutic Implications—A Narrative Review, 2026. https://pubmed.ncbi.nlm.nih.gov/42194502/