Purposes-The aim of this study was to investigate the relation between plasma level of glutamate and extent of radiographic bone erosion of the TMJ in patients with early RA in relation to inflammatory disease activity as well as estradiol and testosterone.Patients and Methods-47 patients (29 women and 18 men) of whom 24 were seropositive were included shortly after being diagnosed with RA. Radiographic signs of bone tissue resorption (erosions) in the TMJ was recorded by cone-beam CT images and an erosion score (0 -24) was calculated for each patient. Venous blood was analyzed for rheumatoid factor, C-reactive protein, erythrocyte sedimentation rate, leukocyte particle count, glutamate, estradiol and testosterone. Nonparametric and parametric statistical methods were used in the analysis when applicable.Results-Resorptive changes of the TMJ were found in a major part of the patients. There was a significant positive correlation between plasma level of glutamate and extension of radiographic erosions that was strongest in the patients with low levels of C-reactive protein, estradiol or testosterone. On the other hand erosions were correlated with C-reactive protein in patients with high levels of estradiol. The highest levels of glutamate were found in patients with low levels of C-reactive protein and estradiol.Conclusion-This study shows that a majority of patients with early RA presents radiographic signs of bone tissue resorption of the TMJ and that circulating glutamate is associated with the extent of these changes. The relationship between glutamate and bone resorption seems to be influenced by systemic inflammatory activity as well as estradiol and testosterone levels.

The aim was to investigate whether bone tissue resorption in early RA is related to crepitus of the temporomandibular joint (TMJ) and systemic levels of inflammatory mediators and markers and sex steroid hormones. Twentynine women and 18 men with recently diagnosed RA were examined for TMJ bone erosions with computerized tomography and TMJ crepitus was assessed. Blood samples were analyzed for glutamate, 5-HT, TNF, IL-1β, IL-6, VEGF, inflammatory markers, and estradiol, progesterone and testosterone. The TMJ erosion score was positively correlated to glutamate, and TMJ crepitus where crepitus, glutamate and ESR explained 40% of the variation in the bone erosion score. In the patients without crepitus, bone erosion score was positively correlated to glutamate, which was not the case in the patients with crepitus. In conclusion, the results of this study show that TMJ bone tissue resorption can be predicted by TMJ crepitus and glutamate in early RA.