Thus, our finding illuminates the current study, which seeks to assess the accuracy of salivary HLA-DR4, MMP-8, ACPA, andP. gingivalis levels in differentiating patients with PD with and without RA from clinically healthy individuals and to correlate these biomarkers with the periodontal parameters for better understanding the immune response and inflammation mechanisms involved in the development and progression of both diseases. Here, MMP8 is linked to rheumatoid arthritis.