# Temporomandibularibular Disorders and Serological Tests in Patients with Rheumatoid Arthritis
## 1 Introduction
Early diagnosis and treatment are associated with better outcomes in terms of survival, which is mainly dependent on the early suppression of disease activity and prevention of functional impairment. Therefore, the model of care, including early diagnosis, is consistently regarded as a standard of care according to current international RA guidelines. Some recent research showed that quality of care in the population is suboptimal, even in efficient healthcare systems, due to delays in referral and diagnosis [20]. It has been recognized that early therapeutic intervention improves clinical outcomes and reduces the increase in joint damage and disability. Certainly, treating patients at a stage at which the evolution of joint destruction can still be prevented would be ideal [1]. The joints are primarily involved but there are other extra-articular manifestations, such as rheumatoid nodules, pulmonary involvement or vasculitis, and systemic comorbidities [8; 9; 10; 11]. Specifically, RA may severely affect the normal functions of temporomandibular joints (TMJs) in a wide range of the population, reported to be from 4.7% to 88% of adults [6]. The involvement of the TMJ follows the same destructive path occurring in other joints, directly correlated with the severity and duration of the RA. In the initial phase, there may be synovial hyperemia, lymphocyte infiltration, fibrinoid degeneration, and granulation tissue until joint degeneration. From that point on, there may be the formation of scarring and fibrous adhesion [21]. The disease may lead to severe TMJ disabilities including arthral gia, limited mandibular movements with related functions, difficulty in eating, morning stiffness during mouth opening upon waking, weakness of the masticatory muscles with decreased bite force, and joint noises [21]. TMJ radiographic records may only show abnormalities in the integrity of the bone cortex, bone erosions, asymmetry and flattening of the condyles, and joint space narrowing. Moreover, these TMJ signs and symptoms are often underestimated or, worse, ignored, so the diagnosis of TMJ involvement comes too late to prevent permanent damage. The monitoring of this joint should be considered to prevent irreversible issues [22; 23]. As abovementioned, RF and ACPA are common, reliable, and regularly used methods of RA assessment [6; 14; 15; 16; 17; 18]. If these indices correlate with temporomandibular disorders (TMDs) [24; 25; 26; 27] in RA patients, then they can be used as potential predictors of TMJ affection in RA patients. In the literature, only two clinical trials evaluated the TMD prevalence and the serological tests in RA patients [6; 28]. The ACPA showed a significant correlation with the development of clinical TMDs. There is still no evidence of the presence of a direct association between serological tests and TMDs. The primary objectives of this study were to evaluate, in patients diagnosed with RA, the possible correlation between serological variables and the main TMD signs and symptoms evaluated through the diagnostic criteria for temporomandibular disorders (DC/TMD). The secondary objective was to check the possible influence of any comorbidities with the different TMD signs and symptoms, or any serological variables.