Losing teeth can do more than affect the ability to enjoy a fresh, crunchy apple or flash a healthy smile. New research suggests that tooth loss – a marker for periodontal (gum) disease – may predict rheumatoid arthritis and its severity.  The more teeth lost, the greater the risk of RA, one study found.

In the study of 636 patients with early arthritis, presented at the 2012 European Congress of Rheumatology in Berlin, 24.2 percent had 10 or fewer teeth, 16.1 percent had 11 to 20, 36.3 percent had 21 to 27 teeth, and 23.3 percent had 28 or more teeth. (A full set of adult teeth, including wisdom teeth, numbers 32.)

At six months’ follow-up, 52 percent had a good response to treatment, 32 percent had a moderate response and 16 had no response. The worst prognosis was for those with the fewest teeth. People with 10 or fewer teeth had more severe arthritis – evidenced by a significantly greater erythrocyte sedimentation rate, higher tender and swollen joint counts, and a higher Disease Activity Score – than those with more than 10 teeth. 

In a separate study presented at the same meeting, Italian researchers reported that tooth loss was associated with joint symptoms in a group of 366 first-degree relatives of people with RA, which put them at increased risk of RA themselves.

Participants with one or more swollen joints had an average of 26 teeth, compared with an average of 29 teeth for those with no swollen joints. The fewer the teeth participants had the greater their risk for joint inflammation, the researchers found. Patients with fewer than 20 teeth had eight times the risk of having at least one swollen joint compared to those with all 32 original teeth.

The Mouth-Joint Connection

The two studies are just the latest in a growing body of research linking periodontal disease and rheumatoid arthritis. In a study of 6,616 men and women who underwent four medical exams between 1987 and 1998 and an assessment for periodontal disease between 1996 and 1998, those who had moderate to severe periodontitis had more than twice the risk of RA compared to those with mild or no periodontitis, says study author Jerry A. Molitor, MD, PhD, associate professor in the rheumatic and autoimmune disease division of the department of medicine at the University of Minnesota, Minneapolis.

Such research grew from earlier observations that people with rheumatoid arthritis tended to have more periodontal disease and people with periodontal disease tended to have more rheumatoid arthritis.

Doctors assumed that periodontal disease was a result of RA itself (stiff, painful hands made oral hygiene difficult) or the medications to treat it (drugs that suppressed the immune system inhibited the body’s ability to fight harmful bacteria in the mouth), says Dr. Molitor. Furthermore, Sjögren’s syndrome with RA diminished production of the mouth’s protective saliva, leaving it vulnerable to disease. 

“There is clearly a relationship between periodontal disease and RA,” says  Dr. Molitor. Yet research in recent years suggests the connection is much more complicated than those earlier assumptions, he says. 

In a 2008 study examining the connection between RA and oral health, German researchers examined the oral hygiene status – by means of a comprehensive oral examination – in 57 patients with RA and 52 healthy controls. While the study found that patients with RA were nearly eight times as likely to have periodontal disease as the healthy controls, the researchers found that oral hygiene alone did not explain the increased risk.