I've spoken to a cardiologist about the teeth brushing thing and he said there actually is a correlation between poor dental hygiene and heart disease. With regards to teeth brushing, the issue there linking to heart health is mainly said to be plaque. I can't remember exactly what he said, but I wouldn't go as far as to say that not brushing your teeth causes heart attacks. I think his message was more along the lines of how brushing is one more thing you can do to avoid further accumulation of plaque in your arteries. If a patient has blocked arteries, they're often advised to make lifestyle changes such as diet and exercise, but nowadays I'm hearing doctors promoting good dental hygiene as well. I think dental hygiene is good regardless, so it's just one more reason to take care of your teeth.
You don't need a 100% blocked artery to have a heart attack. I've met people with less than 60% blocked arteries that had recurring heart attacks in less than a decade and others with 99%-100% blockages that had a one time episode of myocardial infarction with resulting after-effects. Some people have plaque buildup due to diet and lifestyle, and for some, hereditary factors are a stronger influence, so again, I wouldn't say that teeth brushing alone will totally prevent a heart attack. Anyone with even one partially blocked artery should look into treating that though.
