More Studies Link Rheumatoid Arthritis, Periodontal Disease

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The association between periodontal disease, RA is a chicken-or-egg question.

The association between periodontal disease and rheumatoid arthritis (RA) has raised a chicken-or-egg question about any causal relationship between the two conditions.

Last year, US investigators published study suggesting that periodontal infections with the Aggregatibacter antinomycetemcomitans (Aa), a bacteria, could play a role in the pathogenesis of RA and the search for treatment. But as a JAMA commentator recently noted, these findings need to be replicated by different researchers and in different cohorts before gum disease can be identified as an instigator of RA.

Now, a recent study by Finnish researchers suggests a different oral bacteria, P. gingivalis may be involved. “The presence of P. gingivalis in patients with ERA [early rheumatoid arthritis], as observed in our study among the patients with PD 4 mm or more [periodontal probing depth] may be a combining link between periodontal disease and RA.”

The Finns noted that P. gingivalis has been discussed in others’ earlier studies on periodontal disease and RA. Although they did not cite the recent Johns Hopkins School of Medicine work, the Finnish team wrote that their results also agreed with earlier studies published elsewhere concerning associations between periodontitis and RA.

However, this was an ancillary finding for the Finnish team, whose objective was to investigate the role of anti-rheumatic drugs on periodontal health. “The main result of our study was that periodontal health indeed was poorer in patients with RA in general compared with population controls. Nearly 80 percent of patients with ERA and 85% of patients with CRA [chronic rheumatoid arthritis] suffered from periodontitis vs 40% of controls….” the researchers wrote. “The poorer periodontal health could be the result of a weakened immune defense in the host due to RA and future, increased systemic inflammation may initiate or enhance the severity of periodontitis…” wrote Leena Ayravainen, DDS (pictured), and her co-authors from the University of Helsinki.

In the Finnish cohort, previously untreated ERA patients received non-biologic medications and CRA patients, because of a previous insufficient response to synthetic anti-rheumatic drugs, received biologics or a combination of biologic and non-biologics. These drugs neither improved or worsened the gum disease in the 83 patients who participated in the study between September 2005 and May 2014, the study found. The study included 43 controls.

At follow-up, “no improvement could be observed in periodontal status among the patients with RA.” The study also said that its reults "show that biological DMARDs [disease modifying anti-rheumatic drugs] can be used in patients with chronic active RA as they do not worsen periodontitis in these patients.” In the previously untreated early RA patients, “conventional anti-rheumatic treatment did not enhance the inflammation or oral pathogenic microbes.”

These findings appear to contradict earlier results, the Finnish researchers noted. Others have reported in three out of four studies, that the TNT-a (a biologic) suppressed periodontal inflammation in RA patients and three more studies reported non-biologics had a suppressive effect on periodontitis, they wrote.

The Finnish findings also stressed the importance of oral hygiene. “Impaired oral health habits rather than weakened immune defense could partly explain the differences in plaque accumulation and gingival inflammation in patients with RA,” the Finns wrote. “…However, the weakened manual dexterity may have a role in oral hygiene habits and thus these patients need special attention in controlling oral hygiene with suitable individual dental hygiene equipment combined with proper periodontal treatment.”

The earlier work from Johns Hopkins was covered by MD Magazine in December. “Periodontitis in early and chronic rheumatoid arthritis: a prospective follow-up study in Finnish population”, was published online on Jan. 31 in BMJ Open and the JAMA commentary, “To Prevent Rheumatoid Arthritis, Look Past the Joints to the Gums”, was published online ahead of print on March 8th.

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