SOD1 and periodontitis: Before treatment: Control group, SOD (129.93 ± 3.98 U/0.5 mL), thiol (36.99 ± 2.14 μmol/L) Gingivitis group, SOD (88.28 ± 2.56 U/0.5 mL), thiol (30.15 ± 3.13 μmol/L) Periodontitis group, SOD (39.99 ± 3.52 U/0.5 mL), thiol (15.09 ± 2.26 μmol/L) After treatment: Control group, SOD (158.69 ± 3.61 U/0.5 mL), thiol (53.96 ± 1.72 μmol/L) Gingivitis group, SOD (133.56 ± 2.16 U/0.5 mL), thiol (45.83 ± 2.09 μmol/L) Periodontitis group, SOD (61.44 ± 2.67 U/0.5 mL), thiol (27.41 ± 1.88 μmol/L)