The components of the human body are closely interdependent; as a result, disease conditions in some organs or components can influence the development of disease in other body locations. The effect of oral health upon health in general has been investigated for decades by many epidemiological studies. In this context, there appears to be a clear relationship between deficient oral hygiene and different systemic disorders such as cardiovascular disease and metabolic syndrome. The precise relationship between them is the subject of ongoing research, and a variety of theories have been proposed, though most of them postulate the mediation of an inflammatory response. This association between the oral cavity and disease in general requires further study, and health professionals should be made aware of the importance of adopting measures destined to promote correct oral health. The present study conducts a Medline search with the purpose of offering an update on the relationship between oral diseases and cardiovascular diseases, together with an evaluation of the bidirectional relationship between metabolic syndrome and periodontal disease. Most authors effectively describe a moderate association between the oral cavity and cardiovascular diseases, though they also report a lack of scientific evidence that oral alterations constitute an independent cause of cardio - vascular diseases, or that their adequate treatment can contribute to prevent such diseases. In the case of metabolic syndrome, obesity and particularly diabetes mellitus may be associated to an increased susceptibility to periodontitis. However, it is not clear whether periodontal treatment is able to improve the sys - temic conditions of these patients.