This study synthesizes evidence on the impact of subgingival periodontal treatment combined with antibiotics on reducing systemic inflammation markers—C-reactive protein (CRP), interleukins, and tumor necrosis factor-alpha (TNF-α)—in patients with metabolic syndrome (MS) and periodontal disease (PD), compared to supragingival periodontal treatment with placebo. This evidence concerns the gene CRP and periodontal disorder.