There’s no evidence of causality yet, so what?

Sept. 1, 2012
Oral-systemic associations are here to stay despite what the American Heart Association says. The lack of demonstrated causality at this time does not mean that associations do not exist.

By Richard H. Nagelberg, DDS

Oral-systemic associations are here to stay despite what the American Heart Association says. The lack of demonstrated causality at this time does not mean that associations do not exist. The oral cavity does not exist in a disconnected state from the rest of the body. Just because something is not proven at this point does not disprove it either. Lack of evidence of direct causality is not a sound rationale for inaction. There are links that are universally accepted by the medical and dental professions, with the same degree of certainty as the AHA’s accurate statement that causality is not proven.

Among these accepted facts are the following. Periodontal disease has infectious and inflammatory components. These infectious and inflammatory events increase insulin resistance, just as any infection or inflammation does, anywhere in the body. This is a fact.

Atherosclerosis is a chronic inflammatory response of the arterial walls, not a lipid-driven disease as we thought for generations. The root cause of cardiovascular events, including heart attacks and strokes, is atherosclerosis. The process that initiates the buildup of a fatty plaque in an arterial wall is inflammation-driven damage to the inner wall of the artery, the endothelium. Until that happens, all the cholesterol, triglycerides, and other fats in the bloodstream are flowing through in an unrestricted fashion, like water through a garden hose. These are facts.

How does insulin resistance cause atherosclerosis? When insulin is prevented from attaching to the receptor on the cell membrane, the glucose in the bloodstream cannot get into the cells, so it piles up in the bloodstream and leads to high blood sugar levels or hyperglycemia. The pancreas reacts to the elevated blood sugar levels by pumping out more insulin, further elevating insulin levels in the bloodstream. Elevated insulin levels damage arteries in several ways. It worsens dyslipidemia, meaning that it elevates LDL levels (the bad cholesterol) and reduces HDL levels (the good cholesterol). High insulin levels increase blood pressure, promote inflammation, and cause endothelial dysfunction, all resulting in damage to the endothelium. Note that elevated blood sugar levels do not cause these events, but rather, high insulin levels do. It is high levels of insulin that drive arterial disease — not high blood sugar levels, which cause their own constellation of problems. The damaged endothelium then allows LDL cholesterol to migrate from the artery lumen into the wall, where a series of events culminates in the development of an atherosclerotic plaque. These are facts.

The connection to the oral cavity is the fact that periodontal disease increases insulin resistance, which means that periodontal disease is involved at the outset of atherogenesis, when all of this is just beginning. Periodontal disease is not the only thing that increases insulin resistance, but eliminating as many sources of insulin resistance as possible is critical to reducing the risk of cardiovascular disease, especially since periodontal disease is preventable and treatable.

There are other factual pathways as well, including the effect of periodontal disease on Plac-2 levels. Plac-2 is an enzyme. Plac-2 elevation significantly increases cardiovascular disease risk. In fact, a blood test for Plac-2 levels (PLAC Test) is the only FDA-cleared blood test to aid in assessing the risk for both coronary heart disease and ischemic stroke associated with atherosclerosis. A study published in the American Journal of Cardiology in 2006 stated that periodontal disease is associated with elevated Plac-2 levels.

Other associations deal with the effect of periodontal pathogens, independent of periodontal disease. Various studies have shown evidence of a direct relationship between periodontal pathogens and hypertension, a major risk factor for cardiovascular disease. Still others have shown the effect of the periodontal pathogen Pg on heart attack risk.

As dental professionals we have an enormous responsibility to our patients. This includes keeping up with research and deciding how we will incorporate the information into our protocols for addressing disease. The care we provide for our patients may be limited to interventions only in the mouth. The effects, however, are felt throughout the entire body.

RICHARD NAGELBERG, DDS, has practiced general dentistry in suburban Philadelphia for more than 30 years. He is a speaker, advisory board member, consultant, key opinion leader for several dental companies and organizations, and lecturer on a variety of topics centered on understanding the impact dental professionals have beyond the oral cavity. Contact him at [email protected].

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