Inflammation and bony changes at the temporomandibular joint

Cytokines help mediate the acute and chronic inflammation and associated de struction of connective tissue in arthritic temporomandibular joints (TMJ). The proinflammatory cytokines TNF alpha, IL-1 beta, IL-6, IL-8, and IFN-ga mma are associated with inflammation in synovial joints and connective tiss ue destruction. Therefore, the increased levels of these cytokines in the s ynovial fluid of temporomandibular disorder (TMD) patients would be expecte d. Conversely, IL-1ra and IL-10 acts as inhibitors to these proinflammatory cytokines. Thus, in TMD patients, low levels of IL-1ra and IL-10 might be expected. A review of studies from multiple investigators confirms that pro inflammatory cytokine levels increase in TMD patients, IL-1ra levels are al so increased, and IL-10 levels remain unchanged. Because IL-10 can inhibit TNF alpha, IL-1, IL-6, and IL-8, the lack of IL-10 in the TMJ in the face o f the other studies showing increases in TNF alpha, IL-1 beta, IL-6, and IL -8 could partially explain the exacerbation of the associated osteoarthriti s. In addition, although IL-1ra levels are elevated in most of the TMD pati ents, the increases do not appear to be sufficient to inhibit the inflammat ion and connective tissue degradation associated with IL-1 beta. Thus, it a ppears that treatment of TMD requires a delicate balance between proinflamm atory cytokines and cytokine inhibitors such as IL-1ra and IL-10. Copyright (C) 2001 S. Karger AG, Basel.