Periodontal disease is the medical term for gum disease. It can be used to refer to the wide range of gum disease, including gingivitis, which is a mild form of the condition, but is more often used to refer to the second and more serious stage of gum disease, periodontitis. Periodontal disease is among the ten most common diseases that affect humans and is the main cause of tooth loss in adults, so it is important to be aware of the condition and how it can develop. 

If you don't stop the first stage of periodontal disease, gingivitis, it can progress to periodontitis, a chronic inflammatory disease that affects the periodontium - the name given to the tissues, ligaments and bones that surround and support your teeth. If left untreated, periodontitis can severely damage these structures, eventually leading to tooth loss.