IgG antibody to P. gingivalis, P. intermedia, and F. nucleatum, P. gingivalis;PD assessments: CAL, BOP, probing depth;clinical RA assessment: DAS-28, radiological evaluation;laboratory variables: RF, anti-CCP2, hsCRP;HLA-DRB1 status by single-nucleotide polymorphisms. This evidence concerns the gene HLA-DRB1 and rheumatoid arthritis.