On the perception of the preferred jaw position in patients with symptoms of temporomandibular disorders.

AbstractThis paper considers the hypothesis that, in patients with temporomandibular disorders of myogeneous origin, oral muscle hyperactivity originates in deviant motor programs for oral behavior, based on erroneous proprioceptive information. Patients with various forms of TM dysfunction participated in the study; we measured each patient's ability to match jaw separations by referring to a self-generated internal standard, or preferred jaw position (PJP). The PJP establishment and its precision were considered an expression of a patient's propriocepsis. We measured PJP before, during, and after splint therapy in three groups of TMJ patients (a myogeneous, an arthogeneous, and a psychogeneous group) and looked at how values of PJP changed with therapy.This longitudinal study shows that patients with TMJ disorders behave similarly to symptom-free dentate subjects when matching PJP. More than 80% of our patients are unstable in their jaw position preference, but the precision of determinating is constant...