Pain and radiographic changes of the arthritic temporomandibular joint : relation to cytokines in synovial fluid and plasma

Abstract

In patients with rheumatoid arthritis and other inflammatory joint diseases, radiographic changes of the TMJ are frequently observed. Common symptoms of TMJ involvement are pain at rest and on movement of the jaw. This thesis investigated the relationship between pain, radiographic changes and IL-1[beta] and TNF[alpha] levels in plasma and TMJ synovial fluid. The progression of radiographic changes was also investigated in a longitudinal study. A methodological study refined the use of vitamin B12 as an external marker to determine the concentration of TMJ synovial fluid in samples obtained by saline washing.

The subjects of the clinical investigation comprised patients with general arthritides and TMJ pain. TMJ examination included tenderness to palpation and measurement of the pressure pain threshold by an algometer. Pain associated with jaw movements was recorded. Venous blood samples were collected and samples of synovial fluid were obtained using a saline washing technique, with vitamin B12 as an external marker. The cytokine levels in plasma and synovial fluid were analyzed by immunoassays. The subjects underwent tomographic examination of the TMJ; in 21 subjects this was repeated, at a mean interval of 33 months. The extension of erosions (ER), the overall grade of radiographic changes (GR) and progression of bone loss (PROG) were assessed and correlated with IL-1[beta] and CRP.

Pain and tenderness of the TMJ occured independently of ER or GR, with the exception of pain upon maximum voluntary mouth opening (MVM). In joints with pain on MVM or tenderness to posterior palpation, levels of synovial fluid TNF[alpha] were higher than in symptomless joints. Multiple painful jaw movements were associated with elevated plasma TNF[alpha] levels. In the crosssectional part of the study, ER was higher for joints with detectable levels of synovial fluid IL- 1 [beta] than for those without. Both ER and GR were greater in subjects with detectable levels of plasma IL-1[beta] than those without. In the longitudinal study, GR was higher at the second examination than at the first, whereas there was no significant difference between ER at the two examinations. Bone loss, assessed by PROG, progressed between the examinations. There was a positive correlation between the level of CRP and PROG.A positive correlation between plasma IL-1[beta] and PROG was also found for patients with a duration of TMJ disease of < 7 years, or a diagnosis of RA.

In the methodological part, the absorbance peak of the B12-solution with the greatest difference to the plasma peak was at 350 nm. The dilution factors calculated for the capillary tubes (3 [mu]L) and the standard cuvettes [(2.5 mL) had a linear correlation coefficient of r = 0.99. The addition of B12 as a marker did not interfere with the analysis of IL-1 [beta] and TNF[alpha].