Several models of interaction have been proposed for the relationship between RA and periodontitis. Briefly: 1) Infection with periodontal pathogens, particularly Porphrymonas gingivalis (P.g.), initiates the alterations of host proteins through citrullination, which leads to the formation of autoantibodies and cross-reactivity causing autoimmunity and RA; 2) A common inflammatory burden activates both osteoclast function and vascular damage causing a predisposition to both RA and periodontitis; 3) periodontal disease and RA, when they exist together, can cause a cyclical exacerbation of systemic inflammation and a worsening of both diseases (“two hit model”)50 (Figure 2).
Figure 2. Concept of how periodontitis and rheumatoid arthritis might interact.50
A. Periodontitis Precedes Rheumatoid Arthritis.
B. Common Inflammatory Pathways: Osteoclast Activation and Vascular Damage.
C. Two Hit Model of Mutual Exacerbation.