Periodontal disease is a disease of the gum tissue and underlying bone. Unlike gingivitis, periodontitis is associated with irreversible loss of the underlying bone that holds the teeth in. Gum pockets usually open up between the tooth and gum and act as reservoirs for bacteria unless treated. The rate of bone loss varies very much from individual to individual, but if untreated may well lead to tooth loss. Up to 80% of the population will probably get some periodontal disease, and 15-20% of people will lose a significant number of teeth if they do not receive treatment. Like gingivitis, periodontitis is usually painless, and by the time people become aware of problems, usually teeth becoming loose or drifting out of alignment, serious damage has been done. If caught early enough, most periodontal disease can be treated.