Periodontal diseases are infections of the structures around the teeth. These include the gums, the cementum that covers the root, and bone. Although many people think it's normal if their gums bleed when they brush or floss, it's a bad sign. Swollen and bleeding gums are early signs that your gums are infected with bacteria. If nothing is done, the infection can spread. It can destroy the structures that support your teeth in your jawbone. Eventually, your teeth can become so loose that they have to be extracted.