Studies demonstrated that periodontitis is associated with increased systemic levels of cytokines, such as interleukin-1α (12), interleukin-1β (12–14), interleukin-6 (IL-6) (12, 15, 16), C-reactive protein (CRP) (16, 17), interferon-γ and tumor necrosis factor-α (12, 13) in serum or plasma. This evidence concerns the gene CRP and periodontitis.