Unlike dental plaque that we try to brush away, cholesterol, fat, calcium, and other substances in the blood combine and form this type of plaque. Over time, this plaque can build-up on the inner walls of blood vessels causing them to narrow. This is called atherosclerosis. Plaque may also lead to blood clot formation, heart attacks and stroke. The risk of these problems can be reduced by maintaining normal blood cholesterol which sometimes requires medications.