Determinants of Orofacial Pain and Temporomandibular Disorders in People With Rheumatoid Arthritis

Rheumatoid arthritis (RA) is chronic inflammatory autoimmune disease characterized by symmetrical peripheral polyarthritis with consequent joint destruction. Predominantly affecting wrist and foot joints, RA can also affect temporomandibular joint (TMJ) causing temporomandibular disorders (TMDs). 4-80% of RA patients suffer from TMDs.

It remains unclear why some RA patients do not have TMDs and don't suffer from orofacial pain, depression and somatization. The present study was therefore designed to explore the level of cytokines and biochemical parameters from saliva and serum in RA patients and control participants to examine their correlation with TMDs. Study results could provide valuable insights for the understanding of the orofacial pain and depression onset in RA patients Participants would be examined by a non-blinded examiner with knowledge to which group the patient was in. After intraoral examination Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) will be used as an international diagnostic protocol for TMDs. Assessment included clinical examination of TMJs and masticatory muscles with measurement of mandibular dynamics. The participants will be requested to spit 2 mL of unstimulated saliva into a sterile tube with their head slightly bended forward. Saliva samples were stored at -20℃ until analysis. Blood samples will be collected in Vacutaners. Serum calcium (Ca), magnesium (Mg), phosphate (P), uric acid, alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) and gamma-glutamyltransferase (GGT) were measured up to 6 hours after collection. Serum aliquots were stored at -20℃ until cytokine analysis. An Invitrogen assays were used to analyze salivary and serum concentration of IL-4,IL-18 and IFN-γ.