All gum disease is caused by Plaque. Longstanding gingivitis can turn into periodontal disease.
There are a number of different periodontal diseases and they all affect the tissues that support the teeth. When the disease progresses and is longstanding, the bone fixing the teeth to the jaw is lost and this makes the teeth loose. If left untreated, the teeth may eventually fall out.
The problem with gum disease is that it is not easily detected, as it is painless. However should you have red, swollen and bleeding gums, you need to see your dentist as soon as possible. This may also be the cause of bad breath known as halitosis.