CXCL8 and periodontitis: Prior study has detected the significantly increased levels of IL-6, IL-8 and TNF-α in the serum and gingival crevicular fluid of patients with periodontitis.17,18, 19 In our study, the levels of serum inflammatory factors IL-6 and TNF-α in the enrolled patients were improved after 12 months of treatment compared with those before treatment, with more significant decrease in the study group than those in the control group.