Periodontal (gum) disease is an
infection of the teeth, gums, and the bone that surround the teeth.
This infection, combined with your body's reaction to it, is what causes
bone loss.
Shown in the 1st illustration, the
teeth roots extend into the bone of the jaw. This
represents a healthy mouth, since the bone comes up high around the necks
of the teeth.
The 2nd illustration shows advanced
periodontal disease.
The bone level is much lower and uneven, as compared to the healthy mouth
in the 1st illustration.
Once bone has been lost,
it is gone forever. When too much bone is lost, little support is
provided for the teeth, resulting in their getting becomng loose and
having to be removed.