Expression of Interleukin-1 and Temporomandibular Disorder: Contemporary Review of Literature

Objectives: Temporomandibular disorders (TMD) are a group of conditions affecting the temporomandibular joint (TMJ), leading to jaw dysfunction, joint and muscle pain, and a decrease in quality of life. Forces during function impose constant stress on the TMJ, leading to dynamic remodeling and repair of the joint’s components. A communication network of pro- and anti-inflammatory mediators called cytokines maintains the homeostasis of the TMJ. This review will focus on the interleukin (IL) family of cytokines, which have been quantified in TMJ synovial fluids in a variety of studies. IL-1a and IL-1b have pro-inflammatory effects, while the endogenous receptor antagonist (IL-1RA) inhibits the pro-inflammatory effects of IL-1. Conclusions have been made suggesting that elevated levels of the IL-1 family contribute to the initiation and progression of TMD.

Methods: A systematic literature search (2006-2016) to identify eligible studies was completed using the PubMed database. Studies identified used saline irrigation to quantify cytokine profiles in synovial fluid of healthy and/or dysfunctional joints.

Results: The initial search yielded 111 articles, 5 of which met the inclusion criteria after inter-reviewer discussion. Two studies compared cytokine profiles for healthy and dysfunctional joints. One study compared cytokine profiles in groups based on TMD treatment success. The remaining two studies looked solely at healthy joints or diseased joints.
Conclusions: Articles that compared IL-1 concentrations in TMD vs. control groups found significant differences. In general, IL-1 levels in dysfunctional TMJs showed more abundant expression than in healthy joints. Because studies identified only examined synovial fluid and varied on methods, a more complete marker profile is needed in order to gain a better understanding of the pathology of TMD.