Internal derangement of the TMJ: changes associated with mandibular repositioning and orthodontic therapy

Because of its apparent success in relieving symptoms, especially pain, anterior mandibular repositioning therapy is a popular mode of nonsurgical treatment for patients with painful, clicking internal derangement of the temporomandibular joint. Posterior open bites are a frequent consequence of such therapy and may necessitate either continued appliance wear or closure by equilibration, prosthetics, or orthodontics. The anatomic and functional changes that occur subsequent to mandibular repositioning during orthodontic closure of the posterior open bite are not well understood. A case of a patient with a Class II, deep bite malocclusion and painful internal derangement of the TMJ is presented. Transcranial and cephalometric radiographs, arthrograms, and mandibular movement recordings were obtained before treatment and after both repositioning therapy and orthodontic treatment. Regarding occlusal improvement and pain relief, the treatment was successful. However, not all of the changes that occurred during repositioning therapy were maintained after orthodontic treatment. The strategy used in this case (mandibular repositioning/orthodontic finishing) was evaluated by an examination of these anatomic and functional changes with a discussion centered on the possible mechanisms involved.