Further logistic regression analysis suggested that high levels of IL-6, IL-1β, IL-8, BGP, and MMP-8 in GCF were associated with drug treatment failure in patients with severe periodontitis, suggesting that high levels of IL-6, IL-1β, IL-8, BGP, and MMP-8 would lead to increased risk of treatment failure in patients with severe periodontitis. This evidence concerns the gene IL6 and periodontitis.