Periodontal treatment resulted in decreased serum CRP and IL-6 at 24-week follow-up Periodontal treatment resulted in reduced acetylcholine-stimulated vasodilation Delivery of a nitric oxide synthase inhibitor before and after PD treatment resulted in similar acetylcholine-stimulated vasodilation, suggesting role of nitric oxide bioavailability in mechanism of endothelial dysfunction in patients with PD. Here, CRP is linked to endothelial dysfunction.