LAUSR

Despite a trend of decreased annual death rates from coronary artery disease (CAD) in Europe, the prevalence of cardiovascular disease, and especially CAD, is still high in western, but also in developing countries. Risk factors have been well defined including genetic predisposition, hyperlipidaemia, hypertension, diabetes mellitus, physical inactivity and smoking. Furthermore, poor oral health and especially periodontal disease have been repeatedly associated with CAD in observational studies; however, a causal involvement of periodontal disease for the development and progression of atherosclerosis has not yet been unequivocally proved. All association analyses are confounded by the fact that several CAD risk factors also contribute to the risk of periodontal disease, especially cigarette smoking and diabetes mellitus. Thus the controversy is ongoing as to what extent pushing oral hygiene and treatment for periodontal disease is able to prevent cardiovascular events. An important link between poor oral health and atherosclerosis may be vascular inflammation, either as a direct effect of oral pathogens in the vascular wall or by stimulating more globally an inflammatory environment. In fact, experimental gingivitis has induced systemic inflammatory markers in young healthy individuals. In the response to pathogens and/or inflammation, the endothelium is considered to be the prime target. Endothelial dysfunction and subsequent thrombotic events leading especially to obstruction of the small vasa vasorum may translate into functional impairment and structural damage in the vessel walls of larger arteries. Although oral pathogens have also been demonstrated in specimens of atherosclerotic plaques, the detection of viable microorganisms has been difficult (for review see Lockhart et al.). In addition, trials of long-term antibiotic treatments in CAD patients, for example, in the WIZARD study, did not show a reduction in clinical events. However, the CANTOS trial demonstrating a significant reduction of major cardiovascular events in patients after myocardial infarction by targeting inflammation using an interleukin antibody renewed the interest in anti-inflammatory strategies to prevent the development and progression of CAD. To shed more light on the still unanswered question of a potentially causal connection between CAD and oral health, the report by Batty and colleagues in this issue of the European Journal of Preventive Cardiology is an important step forward. These investigators analysed the association between poor oral health and subsequent CAD morbidity and mortality in almost one million people included in the large Korean Cancer Prevention study, as a part of which all participants had an oral examination with a count of lost teeth at baseline. Follow-up was 20 years, with CAD diagnosed using national mortality and hospitalisation registers, and led to the analysis of an impressive number of more than 60,000 events. The main finding of the study was a moderate but highly significant association of tooth loss (seven or more teeth) with CAD events that was similar in men and women, thus supporting previous smaller analyses. The distribution of several established risk factors of CAD varied according to tooth loss, that is, some factors were more frequent in patients without tooth loss (physical inactivity, family history of cardiovascular disease), whereas others were less frequent in this group (smoking, hypertension, elevated cholesterol, diabetes). Next, the authors analysed the effect of the most important confounding factor, that is, smoking. Interestingly, when restricting their analysis to never-smokers, the association persisted in women, but was no longer apparent in the male population. Although this gender difference appears to be clear at first glance, the lack of confounding effects of smoking in women has to be interpreted with caution as only a very small minority of Korean women are smokers. What to conclude from this analysis? First, several limitations of the study have to be noted: the main