In summary, current evidence demonstrated that MMP-9-753 C/Tpolymorphism reduced the risk of periodontitis, MMP-3-1171 5A/6A and MMP-8-799 C/Tpolymorphisms increased the risk of periodontitis, and MMP-2-753 C/T was not associated with risk of periodontitis. The gene discussed is MMP2; the disease is periodontitis.