The relationship between fibromyalgia and temporomandibular disorders: prevalence and symptom severity.

Objective: To determine the prevalence of muscular or myofascial temporomandibular disorders (TMD) in fibromyalgia (FM) and the prevalence of FM in TMD; and to determine which characteristics best distinguish the 2 disorders.

Methods: 39 consecutive patients with TMD seen in a TMD clinic and 60 patients with FM were examined according to Research Diagnostic Criteria (RDC) for TMD and the American College of Rheumatology 1990 Criteria for the Classification of Fibromyalgia. All patients completed the questionnaires of the RDC and a health status instrument that assessed pain, function, sleep disturbance, fatigue, and psychological status (CLINHAQ).

Results: A small proportion of patients with TMD (18.4%) also had FM, but most of those with FM (75.0%) satisfied criteria for muscular (myofascial) TMD. Patients with FM had lower pain thresholds and more severe manifestations of all disease measures (e.g., pain, fatigue, sleep, etc.) compared to those with TMD. As might be predicted, they also had more painful body regions. Patients with FM also differed significantly from those with TMD in self-reported work ability and health assessment. The features that best differentiate FM from TMD are functional disability, reports of work difficulty, and general dissatisfaction with health.

Conclusions: TMD is a local disorder and FM a generalized disorder, and there is less evidence of distress in those with TMD. TMD is a separate disorder from FM, but many patients with FM have TMD symptoms.