How concerned should I be if I experience bleeding after brushing or flossing my teeth? If you are experiencing bleeding of the gums it is important not to ignore it, as it might be a sign of underlying bacterial problems. If left untreated it can have devastating effects on the health of your teeth. Gingival bleeding generally has two main causes – trauma from brushing or flossing too hard, and gingivitis. Gingivitis is distinct from localised trauma as the gums will appear