Gum disease or more accurately periodontitis is actually a class of diseases affecting the supporting structures of the teeth. The word periodontitis can be best understood when broken down into its parts. “Perio-” means around, and “dont” refers to the teeth, and “-itis” means inflammation.
There are many types of periodontitis including a few rare ones, but for this discussion I will describe the typical path and onset of the disease. It is worth mentioning here that periodontitis affects much more than your teeth. There are strong links between periodontitis and cardiac problems and also between expectant mothers with periodontitis and low birth rate of the newborn.
The first stage is called "gingivitis" and is characterized by gum tissue that is red, puffy, and bleeds easily when touched with a toothbrush, floss or dental instrument. These are inflamed gingiva or gums. This inflammation is caused by a buildup of a soft, sticky layer of bacteria called plaque. It is constantly forming on the teeth. Usually it is invisible to the naked eye, but when a person is not brushing adequately, it can build up to where it appears to be a thick whitish coating on the teeth usually at the gum line. Treatment of gingivitis is usually very simple. Remove the plaque with a dental office cleaning, keep the teeth clean and it is completely reversible.
The second, third, and fourth stages are initial, moderate, and advanced "periodontal disease", respectively. These stages are different from gingivitis because the infection has destroyed the bone supporting the teeth, causing irreversible damage and possible tooth loss. The treatment is more involved at these stages, usually consisting of a special cleaning with anesthesia and sometimes surgery.
Periodontitis is, in most cases, a completely preventable disease. It is one of the things that we always check for at routine visits and why dentists recommend preventative cleanings every six months.