Rheumatoid Arthritis and Gum Disease
Research suggests that taking care of your teeth may be a good way to take care of your joints.
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.
A separate study out of India, which was published this year in the Annals of the Rheumatic Diseases, found twice as many cases of periodontal disease in 91 patients with RA compared to 93 patients without RA. Because none of the people with arthritis had taken disease-modifying antirheumatic drugs (DMARDs), the drugs’ suppression of the immune system could not be blamed for the disparity.
While research hasn’t proven a cause and effect, increasingly it is showing that periodontal disease in people with RA doesn’t always come after RA – in some cases it precedes it, says Dr. Molitor.
A Common Pathway
Researchers studying the RA-periodontal disease connection have found likenesses in the joint and oral tissues, as well as in the inflammatory processes that affect them.
“If you look at the tissues of the mouth in periodontitis and the tissues of the joint in RA, there are a number of similarities – including the types of cells that are infiltrating tissues of the mouth in periodontitis and the tissue of the joint,” says Clifton O. Bingham III, MD, associate professor of medicine and director of the Johns Hopkins Arthritis Center at Johns Hopkins University in Baltimore. He also notes that the levels of proinflammatory proteins like tumor necrosis factor, interleukin-1 and interleukin-6 are also similar in RA and periodontitis.
Research has also shown a genetic link between the two. In a study published in Journal of Periodontology, scientists in Israel found HLA-DR4 – a genetic type that occurs with high frequency in people with rheumatoid arthritis – in 8 out of 10 patients with rapidly progressive periodontitis, compared to just a little over a third of a healthy control group.
Such findings led doctors to believe that there may in fact be a relationship between the two driven by an underlying disease process, says Dr. Bingham.
A potential advance in the understanding of that disease process came around a decade ago when scientists began to understand that one of the early markers of RA is the development of antibodies to citrullinated peptides.
Citrullination is when a protein undergoes a molecular change in structure, says Dr. Bingham. In RA, that change results in the immune system seeing the protein as a foreign body and mounting an attack against it by creating anti-cyclic cirtrullinated (anti-CCP) antibodies. (The presence of these antibodies is associated with more severe RA.) One of the oral bacteria involved in periodontitis has been found to induce citrullination.
Dr. Molitor’s study, which was presented at the 2009 scientific meeting of the American College of Rheumatology, found that people with periodontitis who tested positive for anti-CCP antibodies were more likely to have moderate to severe periodontitis and be a smoker, a risk factor for both RA and periodontal disease. These findings suggest that bacteria in the mouth could actually be a cause of RA or that existing periodontal disease could be triggering rheumatoid arthritis.
In people with a genetic susceptibility to RA, citrullination of particular proteins will cause an immune response against those proteins. “So everybody has citrullination,” says Dr. Bingham. “If you are unlucky enough to have citrullination occurring in the wrong place or against the wrong protein, your body will make an immune response against it and that can be one of the early markers events in the development of RA.”
If oral bacteria are involved in the development or progression of RA, or inflammation in the mouth somehow fuels inflammation in the joints, one might reason that clearing up the periodontal disease would also help prevent or treat RA.
At least one small study suggests that may be the case. In a study of 40 people with both RA and periodontal disease, researchers at Case Western University School of Dental Medicine and University found that those who received nonsurgical treatments for their gum disease reported significantly more improvement in their RA symptoms than those who received treatment for RA only.
Dr. Bingham says more research is needed to better determine whether treating periodontal disease improves or and if efforts to prevent periodontal disease might also help prevent RA. In the meantime, he says, there is reason for people with RA and their doctors to pay particular attention to oral health.
“My bottom line is that we find such a high prevalence of periodontal disease in patients with rheumatoid arthritis and given that there is this highly plausible biological connection between these two disease processes, we need to pay attention to the oral cavity in patients with RA and refer people for dental and periodontal evaluation and treatment,” says Dr. Bingham.
If you have RA, the message is to take care of your teeth. Schedule regular dental exams, eat healthfully, brush and floss and, if you have trouble taking care of your teeth due to stiff, painful hands or jaws, speak to your dentist or occupational therapist about ways to make dental care easier, including the use of special assistive devices.
It’s also important to work with your doctor to get your arthritis under control. Doing so could potentially save both your joints and your teeth.
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