Comparison of masticatory dysfunction in temporomandibular disorders and fibromyalgia

Many theories have been proposed as to the relationship between fibromyalgia (FM) and temporomandibular disorders (TMD). The aim of this study was to investigate the clinical features of the involvement of the stomatognathic system in patients with fibromyalgia, and to compare signs and symptoms of masticatory dysfunction between TMD and FM patients.

The study sample consisted of 30 subjects with fibromyalgia recruited at the Rheumatology Disease Department, University of Pisa, Italy, and of 30 with temporomandibular disorders at the Section of Prosthetic Dentistry, Department of Neurosciences, University of Pisa, Italy. Masticatory dysfunction has been compared between the 2 groups by means of a clinical assessment conducted according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). Patients of the TMD group underwent a rheumatologic examination to investigate for the presence of previously undiagnosed fibromyalgia.

As regards specific clinical variables and RDC/TMD diagnoses, differences between the 2 groups appear to be not relevant, with the exception of the values of mouth opening, both voluntary and passive, and the presence of trigger points. FM patients showed a decrease in both maximum voluntary and passive mouth opening which was about 2 mm worse than that recorded in TMD patients. FM patients also showed a significantly higher number of trigger points, even though muscle palpation evoked tenderness in the same number of sites in the 2 groups.

This study showed that most patients with fibromyalgia (86.7%) report signs and symptoms localized at the stomatognathic system; by contrast, only a minority of patients with temporomandibular disorders (10%) are actually affected by fibromyalgia.