Cardiovascular disease (CVD) is now considered to be a multi causal disease. Numerous studies have focused on major risk factors as hypertension, smoking, cholesterol, genes, biomarkers, sex, and family history. Yet they do not explain all CVD events and the associated patophysiology. Mounting evidence is being published on the association of oral infections, periodontal infections in particular, to the disease processes of the cardiovascular system leading to myocardial infarction, stroke, or other cardiovascular diseases. Different causal pathways are being explored. The question arises as to when we have sufficient evidence of causality to mark a factor amenable to prophylactic measures against cardiovascular disease. Causality is the term for studying the association between different factors and the development of a disease or health condition and the disease occurrence and its trends. Causal inference involves making conclusions from current knowledge. Which theoretical framework is available when studying disease and risk factors? Causality is discussed in the context of epidemiology, statistics, philosophy, and evidence based medicine.