Periodontal disease, or gum disease, is a severe infection of the gums. It starts out as plaque that forms calculus or tartar around the teeth and bacteria gets trapped around the gum line. Symptoms in the early stages include bad breath, swollen gums and bleeding gums. If the condition progresses to periodontitis or advanced periodontitis, the bacteria destroys the gum tissue and supporting bone structure. If this continues, you will lose your teeth.