Thereby an increase of pro-inflammatory cytokines such as interleukin (IL)-1β, -2, -6, -8, tumour-necrosis-factor (TNF), and interferon-gamma (IFN-γ) was seen in periodontitis, while a decrease of inflammation was detected after periodontal treatment [19,20,21,22,23,24]. This evidence concerns the gene IFNG and periodontitis.