Obesity may affect periodontal health by inducing gingival oxidative damage through increased production in circulating reactive oxygen species (ROS). Several studies have demonstrated that 8-OHdG in bodily fluids can act as a biomarker of oxidative DNA damage in periodontal diseases and for evaluating the effect of periodontal treatment. In the present study we hypothesized that high ROS levels in circulation may increase oxidative stress levels in the gingival crevicular fluid (GCF) and saliva in obese patients with periodontal disease, thus periodontal therapy could have positive effects on ROS levels.