Pressure Pain Thresholds in the Craniofacial Region of Female Patients with Rheumatoid Arthritis

Aims: To determine the temporomandibular joint (TMJ) pressure pain threshold (PPT) in female patients with rheumatoid arthritis (RA) and TMJ involvement in comparison with healthy females, in order to determine its clinical usefulness for local pain assessment. Methods: Forty-two female patients with the diagnosis of RA, 17 of them positive and 25 negative for rheumatoid factor were investigated, as well as 17 healthy females. A pressure algometer was used to assess the PPT over the TMJ and (as a reference) the center of the glabella. The mean of the second and third TMJ PPT was used in the analysis, and the ratio between the TMJ PPT and the PPT of the reference site (PPT ratio) was calculated. Temporomandibular joint resting pain and pain upon maximum voluntary mouth opening was assessed by a visual analog scale on each side. Results: The TMJ PPT (median/10th to 90th percentile) and PPT ratio were significantly lower in the RA patients (148/64 to 220 and 0.63/0.40 to 1.01, respectively) than in the healthy individuals (217/111 to 352 and 0.85/0.51 to 1.25), but the overlap was considerable. Conclusion: This study shows that the PPT of the TMJ in RA patients is lower than in healthy individuals and that it can be used for pain assessment. However, the clinical use of the TMJ PPT and PPT ratio measurements alone is limited from a diagnostic point of view. Keywords: pain, pain threshold, pressure, rheumatoid arthritis, temporomandibular joint