Think flossing and brushing is helping to fight off heart disease and stroke? Think again.

An expert panel of dentists and cardiologists, writing in the American Heart Association journal Circulation, says there is no evidence that treating or preventing gum disease has any direct effect on heart health.

That's a big turnaround. For the past decade, the medical establishment has been telling people that cardiovascular disease can be caused by poor oral hygiene. Why the change?