Severe periodontitis has been associated with increased systemic inflammation. In a three-arm preliminary randomized trial, we investigated the impact of standard (SPT) and intensive periodontal therapy (IPT) on serum inflammatory markers and cholesterol levels. Medical and periodontal parameters, C-reactive protein (CRP), interleukin-6 (IL-6), total cholesterol, and LDL cholesterol were evaluated in 65 systemically healthy subjects suffering from severe generalized periodontitis. Two months after treatment, both SPT and IPT resulted in significant reductions in serum CRP compared with the untreated control (0.5 +/- 0.2 mg/L for SPT, P = 0.030 and 0.8 +/- 0.2 mg/L for IPT, P = 0.001). Similar results were observed for IL-6. Changes in inflammation were independent of age, gender, body mass index, and ethnicity, but a significant interaction between cigarette smoking and treatment regimen was found. The IPT group also showed a decrease in total and LDL cholesterol after 2 months. Analysis of these data indicates that periodontitis causes moderate systemic inflammation in systemically healthy subjects.