Periodontitis (pyorrhea) is a severe form of gingivitis in which the swelling of the gums extends to the supporting structures of the tooth.
Periodontitis is one of the main causes of tooth loss in adults and is the main cause in older people. Infection erodes the bone that holds the teeth in place. The erosion weakens the attachments and loosens the teeth. An affected tooth may eventually fall out or need to be pulled
Most periodontitis results from a long-term accumulation of plaque and tartar on the teeth and the gums. If the disease continues, eventually so much bone is lost that the tooth may become painfully loose.
The rate at which periodontitis develops differs considerably, even among people with similar amounts of tartar.
The early symptoms of periodontitis are bleeding, red gums, and bad breath. Dentists measure the depth of the pockets in the gums with a thin probe, and x-rays show how much bone has been lost. As more and more bone is lost, the teeth loosen and shift position. Frequently, the front teeth tilt outward. Periodontitis usually does not cause pain until the teeth loosen enough to move while chewing or until a collection of pus forms.
Source: Merck- Home Health Handbook