This paper reviews the association between periodontitis and CVD. In addition, the potential mechanisms of any association between periodontitis and CVD as well as the effects of periodontal treatment on CVD are herein discussed. Among the studies carried out by this group and others on coronary artery diseases, peripheral arterial diseases, abdominal aortic aneurysm, and Buerger's disease, periodontopathic bacteria were frequently detected in the diseased blood vessels, thus suggesting an association between periodontitis and CVD. The potential mechanisms of the association between periodontitis and CVD are not fully elucidated. However, inflammation and some autoimmune mechanisms, including molecular mimicry between the periodontopathic bacteria and host molecules, are suggested. The effects of periodontal treatment on CVD might thus vary among the different treatment modalities, and full-mouth mechanical debridement might induce strong transient systemic inflammatory responses in comparison to the quadrant-wise mechanical debridement.