Gum disease is caused by a sticky film of bacteria called plaque. Plaque is always forming on your teeth, but if they aren’t cleaned well, the bacteria in plaque can cause your gums to become inflamed. When this happens, your gums will pull away from your teeth and form spaces called pockets. Plaque then gets trapped in these pockets and cannot be removed with regular brushing. If untreated, gum disease could lead to bone and tooth loss.