Heart and stroke researchers have found that people with periodontal disease are almost twice as likely to suffer from coronary artery disease as those without periodontal disease. Furthermore, the risk of stroke is 2½ times as high in people with periodontal infections. Several theories exist to explain the link between periodontal disease and heart disease. One theory is that oral bacteria enter the bloodstream through swollen gum tissues and attach to fatty plaques in the coronary arteries (heart blood vessels), contributing to clot formation and thickening of the walls of the blood vessels. Over time this build up can obstruct normal blood flow and restrict the amount of nutrients and oxygen required for the heart to function properly, resulting in a heart attack. Another possibility is that the inflammation caused by periodontal disease increases plaque build up, which contributes to hardening of the arteries.