If gingivitis is not treated, it will often advance to periodontitis. Periodontitis is a severe stage of gum disease where the gums pull away from the teeth and form gaps (often called ‘pockets’) that become infected. Your immune system will then attempt to fight the bacteria and plaque in these pocket as it spreads and grows below the gum line. The body’s natural response to infection is to break down bacterial toxins, which consequently starts to break down the bone and connective tissue of the gums that hold the teeth in place. If periodontitis is not treated, the bones, gums and tissue that are infected and support the teeth, are destroyed. The teeth may eventually loosen and may have to be removed, or may fall out naturally.