RA afflicts 0.5‒1% of the population worldwide.1,2 These two chronic inflammatory diseases have some similarities in their clinical and pathological features.1,3-5 Similar immunological response, active tissue destruction, cellular infiltrations and inflammatory mediators (PGE-2, TNF-∝ and IL-1) exist in both diseases.6,7 Antibodies against a variety of periopathogens were found in the serum and synovial fluids from patient with RA.8-10 Rheumatoid factor (RF) has been detected in the gingival tissue, subgingval plaque, saliva and serum of patients with periodontal diseases. This evidence concerns the gene TNF and rheumatoid arthritis.