Rheumatoid Arthritis and Temporomandibular Pain

Individuals with seronegative early rheumatoid arthritis (RA) and those at risk for RA are significantly more likely to experience pain associated with temporomandibular disorders (TMDs), including temporomandibular joint disorder (TMJ), compared to healthy controls, based on new data from 150 adults.

Further, people with systemic diseases such as RA may develop pain and disorders in the temporomandibular joint, wrote Johanna M. Kroese, DDS, of the Academic Centre for Dentistry Amsterdam, The Netherlands, and colleagues. However, studies of TMD in people with early RA and those identified as at risk for RA, are limited, and tend not to use standardized diagnostic criteria for TMD, the researchers noted. For instance, palpation is often used in diagnosis.

To dig into this topic, Dr. Kroese’s team recruited 150 individuals in three groups:¹

• 50 patients with early rheumatoid arthritis based on the current EULAR criteria

• 50 individuals at risk for rheumatoid arthritis

• 50 healthy controls

The early RA and at-risk individuals were identified through Reade, a rheumatology clinic in Amsterdam. TMD diagnosis was based on the standardized diagnostic criteria (DC/TMD), which included five categories attributable to TMD:

• myalgia

• arthralgia

• articular disk displacement

• degenerative joint disease

• headache

Rheumatoid Arthritis and TMD Pain: New Links Found

Overall, the prevalence of TMD was not significantly different among the three groups, diagnosed in 20, 19, and 14 individuals in the early RA, at-risk, and control groups, respectively.

However, individuals in the at-risk group were more likely than healthy controls to have a TMD pain-related diagnosis (16% vs. 4%). The difference between the early RA group and controls was not significant. However, TMD pain was reported more frequently in the subgroup of individuals with early RA who were seronegative compared to those who were seropositive (33% vs. 8%).¹

Bruxism in Rheumatoid Arthritis

The team also explored the potential impact of bruxism, which was assessed based on self-reports and clinical features. A total of 34 participants were diagnosed with probable sleep bruxism, including 9 individuals with early RA, 14 at-risk RA individuals, and 11 controls. The researchers found no difference in probable sleep bruxism diagnosis between participants with and without TMD diagnosis (28% vs. 20%). “However, participants with a TMD-pain diagnosis had a probable sleep bruxism diagnosis more often than participants without a TMD-pain diagnosis,” of 47% vs. 20%, they reported.

Jaw Pain in Rheumatoid Arthritis

In looking at pain and non-painful symptoms in study participants without an official TMD diagnosis, they identified 5 early RA patients (4 of whom were seropositive), 2 at-risk individuals, and one control who reported pain influenced by jaw function.

The results suggest a high prevalence of TMD pain in seronegative early rheumatoid arthritis and in at-risk rheumatoid arthritis, and clinicians are encouraged to be alert to the potential of TMD pain in these populations.

“Individuals who might benefit from further TMD examination and management can then be identified and referred to a suitable dental healthcare provider, preferably with a specialization in orofacial pain and dysfunction,” emphasized Dr. Kroese’s team in their paper.¹

Study Limitations

The findings were limited by several factors, including the small subgroup numbers used for comparison, and the lack of specific information on the nature of the TMD pain. Another limitation was the reliance on self-reports for bruxism diagnosis. However, Dr. Kroese’s team wrote that their results were strengthened by the extensive TMD examination, inclusion of bruxism as a possible pain factor, and use of a control group.

Assessing for TMD Pain in Rheumatoid Arthritis: Practical Takeaways

The study is important at this time “because the available literature did not provide sufficient information on temporomandibular joint involvement in early rheumatoid arthritis (RA) patients and individuals at risk of RA,” Dr. Kroese told PPM. “To consider all disorders of the masticatory system, we used the internationally composed and validated diagnostic criteria for temporomandibular disorders.”

Dr. Kroese added that she was surprised by some of the study findings. “We did find a significantly higher prevalence of TMD pain in the individuals at risk of RA compared to the control group, while we did not find this difference for the early RA group,” she noted. “In this latter group, systemic RA medication seemed to have had a positive effect on TMD pain soon after the start of the treatment. Interestingly, this particularly seemed to be true for seropositive RA patients; within the early RA group, we found a significantly higher prevalence of TMD pain in seronegative patients compared to seropositive patients,” Dr. Kroese explained.

“The results of our study suggest that health professionals, medical doctors and dentists alike, should be alert to the possibility of TMD pain in individuals at risk of RA and in seronegative early RA patients, and thus suggests a direction for offering customized care,” added Dr. Kroese.

“Since TMD pain concerns the complex jaw function system and requires specialized care, we recommend referring patients to a suitable dental healthcare provider, preferably with a specialization in orofacial pain and dysfunction,” she emphasized. “As suggested in our article, the DC/TMD symptom questionnaire could be a useful tool for health professionals to screen for possible TMD pain, in order to identify individuals that might benefit from referral.”

“Future research should focus on screening larger groups of patients, to be able to better distinguish between types of TMD, and to further explore the difference between seropositive and seronegative RA patients,” said Dr. Kroese. “Given the number of participants in our study, we combined the prevalence of TMD pain originating from the muscles and the joints when analyzing the results,” she said.

Rheumatoid Arthritis and Characterization Challenges

“This is an ambitious study designed to evaluate the characteristics of TMJ in early onset RA and in subjects at risk for RA,” said Don L. Goldenberg, MD, emeritus professor of medicine, Tufts University School of Medicine, and a member of the PPM Editorial Board.

However, Dr. Goldenberg does not feel that the study provides enough insight to prompt clinicians to be alert for specific issues. He noted that a TMJ diagnosis is subject to various interpretations, and, in this study, the number of subjects and, therefore – the statistical differences – were too small to use as a foundation for making conclusions.

“The vast majority of individuals with TMJ do not have jaw joint pathology and this includes subjects with RA,” Dr. Goldenberg said. “One of the reasons that the estimates of TMJ in RA are so varied is because some studies focus on those RA patients with jaw pathology, whereas other look at patients with clinical TMJ,” he explained. “In RA early onset or at-risk subjects, the majority of subjects who complain of TMJ symptoms will not have any jaw pathology, but the TMJ symptoms reflect increased generalized pain, including the 20% to 30% of subjects who would meet criteria for fibromyalgia,” he noted.

“People at risk for RA represent a poorly-characterized group,” added Dr. Goldenberg. “Further research on this topic would benefit from a much larger study with three better-defined groups, such as established RA, early onset RA, and normal controls,” he suggested. Other useful areas for research include efforts to distinguish subjects with jaw joint pathology, Dr. Goldenberg added.