Failing to brush your teeth properly could potentially lead to fatal heart problems, as bacteria loitering in the mouth may cause life-threatening blood clots, which could trigger a rare condition called infective endocarditis, the Daily Mail reported. Once in the blood, the bacteria can prompt the blood to clot. Hidden inside the clots, the bacteria are shielded from the immune system and antibiotics. A 2010 study found poor oral hygiene is linked to an increased risk of other conditions such as heart attacks or strokes.