Risks The study will require drawing blood from your arm. Veins and arteries vary in size from one person to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others. Other risks associated with having blood drawn are slight but may include bleeding, fainting or feeling light-headed, hematoma (blood accumulating under the skin), and infection (a slight risk any time the skin is broken). In rare instances, it may cause severe pain of infection. Depending upon the complications, your dentist may decide to remove the PRP completely out of the root canal and the use other procedures to treat your tooth. Should root canal failure occur, further dental treatment will be rendered at no charge to you.