Temporomandibular Disorders and Oral Features in Early Rheumatoid Arthritis Patients: An Observational Study

Aims: Temporomandibular disorders (TMD) represent a heterogeneous group of inflammatory or degenerative diseases of the stomatognatic system, with algic and/or dysfunctional clinical features involving temporomandibular joint (TMJ) and related masticatory muscles. Rheumatoid Arthritis (RA) is an autoimmune polyarthritis characterized by the chronic inflammation of synovial joints and oral implications such as hyposalivation, difficulty in swallowing and phoning, feeling of burning mouth, increased thirst, loss of taste or unpleasant taste and smell, dental sensitivity. The aim of this observational study was to investigate the prevalence of TMD symptoms and signs as well as oral implications in patients with Early Rheumatoid Arthritis (ERA), that is a RA diagnosed within 12 months, compared with a control group. Methods: The study group included 52 ERA patients (11 men, 41 women) diagnosed according to the 2010 ACR/EULAR Classification Criteria for Rheumatoid Arthritis. A randomly selected group of 52 patients not affected by this disease, matched by sex and age, served as the control group. The examination for TMD signs and symptoms was based on the standardized Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) by means of a questionnaire and through clinical examination. Results: Regarding the oral kinematics, the left lateral excursion of the mandible was restricted in statistically significant way in ERA patients (p=0.017). The endfeel values were significantly increased in ERA group (p=0.0017), thus showing the presence of a higher muscle contracture. On the other side, the study group complained less frequently (67.3%) of TDM symptoms (muscle pain on chewing, pain in the neck and shoulders muscles, difficulty in mouth opening, arthralgia of TMJ, tinnitus) than controls (90.4%) (χ(2)= 8.301 p=0.0039). The presence of TMJ noises was significantly lower in the study group (χ(2)= 3.869 p=0.0049), as well as presence of opening derangement (χ(2)= 14.014 p=0.0002). The salivary flow was significantly decreased in the study group respect to the control one (p<0.0001). Conclusions: The data collected show a weak TMJ kinematic impairment, a paucisymptomatic muscle contracture (positive endfeel) and a remarkable reduction of salivary flow in ERA patients. Myofacial pain (MP) evoked by palpation was more frequent and severe in the control group than in the study one, this result being highly significant.