Approximately 75 percent of the adult population has some level of periodontal disease, according to the American Academy of Periodontology. Periodontal disease is a serious bacterial infection that destroys the bone and connective tissue that holds the teeth in place, and is the primary cause of rotting teeth. Although preliminary studies suggest a relationship between gum disease and other health problems, the National Institute of Dental and Craniofacial Research says further studies are required to confirm a causal relationship.

Oral bacteria is a serious risk factor for cardiovascular disease, says Robert J. Genco, oral biologist and chief researcher from the University at Buffalo School of Dental Medicine. In a review of 225 veteran outpatients, researchers found cardiovascular disease was more prevalent in patients with advanced periodontal disease than those with good oral health. In another study, the University at Buffalo School of Dental Medicine cites three specific types of bacteria commonly present in gum disease that were found to increase the risk of heart attack by 200 to 300 percent. In a consensus paper jointly prepared by cardiologists and periodontists, the authors call for a joint treatment protocol to treat and educate dental and heart patients about the correlation between the two diseases.

The body’s natural response to infection is inflammation, and the inflammatory response of periodontal disease increases the level of inflammation throughout the entire body, says the American Academy of Periodontology. People with chronic inflammatory diseases such as diabetes are susceptible to infections, which make them more vulnerable to the complications of their disease. Untreated gum disease can raise blood sugar levels in the diabetic and increase the likelihood of additional inflammatory response.

Rheumatoid arthritis is an autoimmune disease in which the body attacks healthy tissue and causes chronic inflammation of the joints. Because, in severe cases, RA can deform joints and limit manual dexterity, researchers presumed the high rate of periodontal disease in RA patients was related to limited dental hygiene. In a study that examined the oral health of 57 RA patients, researchers found the occurrence of periodontal disease was eight times greater in RA patients than in a healthy control group. Although oral hygiene is a factor, the study results point to a potential relationship between systemic inflammation and the occurrence of gum disease, according to Dr. Kenneth Kornman, editor of the "Journal of Periodontology," which published the study in June 2008.