This form of gum disease does not include any loss of bone and tissue that hold teeth in place. Periodontitis. When gingivitis is not treated, it can advance to periodontitis (which means inflammation around the tooth.) In periodontitis, gums pull away from the teeth and form pockets that are infected.The body's immune system fights the bacteria as the plaque spreads and grows below the gum line.his form of gum disease does not include any loss of bone and tissue that hold teeth in place. Periodontitis. When gingivitis is not treated, it can advance to periodontitis (which means inflammation around the tooth.) In periodontitis, gums pull away from the teeth and form pockets that are infected.