The plotted ROC curves showed a good predictor value of the MMP-9/TIMP-1 ratio, (MMP-8 + MMP-9)/TIMP-1 ratio, and HGF (as top three), followed by the MMP-9, MMP-2, MMP-8 + MMP-9 sum and the MMP-8/TIMP-1 ratio, for differentiation of periodontitis versus health conditions (AUC ≥ 0.95). The gene discussed is HGF; the disease is periodontitis.