ALAN G. GLAROS
Temporomandibular disorders (TMDs) are important disorders for dentistry, medicine, and psychology. TMDs are a heterogeneous collection of disorders involving the muscles of mastication and the hard and soft tissues of the temporomandibular joint (TMJ), and are sometimes called TMJ disorders. Dental professionals and other health care professionals recognize psychological and emotional factors as playing key roles in the etiology, maintenance, and treatment of TMDs (Dworkin & LeResche, 1992). This biopsychosocial approach (Greene & Laskin, 2000) creates an increasing role for clinicians using biofeedback in the treatment team for TMDs.
Many fine, comprehensive reviews of TMDs are available (Fricton & Dubner, 1995; Glaros & Glass, 1993; Sessle, Bryant, & Dionne, 1995), and excellent patient education is available from the National Institute of Dental and Craniofacial Research (http://www.nidcr.nih.gov/news/ pubs/tmd/menu.htm). This chapter presents data on TMDs that can help practitioners using biofeedback understand the relationship between psychological, behavioral, or emotional factors and TMD symptoms. This understanding should then serve as a basis for treatment appropriate to the underlying pathogenesis. (Throughout the chapter, italics on first use of a term in text indicate that the term is included in the glossary at the chapter's end.)
The TMJ is a dynamic complex that includes the mandibular condyle, the articular disc, the articular fossa of the temporal bone, and the associated membranes, fluids, and ligaments (Figure 15.1). The condyles arise as vertical projections of the U-shaped mandible, and they articulate with the cranium in the concave mandibular fossae of the temporal bones. The disc consists of dense fibrous connective tissue; it lacks nerves and blood supply. These structures and the associated nerves and vasculature provide for normal functions of the teeth and jaw. Normal function of the TMJ is complex, involving two separate components to its movement. Upon initial opening, the joint works on a ball-and-socket or hinge principle in which the condyle rotates within the fossa. The disc remains in the fossa between the condyle and the temporal bone. As the jaw continues to open, the condyle translates ("dislocates") over a bony, articular eminence in the upper jaw. The articular disc slides between the eminence