Analysis of temporomandibular joint function after orthognathic surgery using condylar path tracings

Condylar path tracings provide quantitative and qualitative data regarding the functional status of the temporomandibular joint. This study was designed to identify the functional status of the TMJ by means of condylar path tracings before treatment and to monitor the response of the TMJ to orthognathic surgery. Baseline data for condylar tracings using a sagittal recording device were established in relation to normal limits for opening, protrusive, and medial excursions of the mandible. In 54 patients 108 joints were studied before and up to 1 year after orthognathic surgery. Internal derangements were identified with condylar tracings before treatment in 72% of all joints studied. Also, condylar tracings identified internal derangements that were not found on clinical examination in 11 of 39 patients. Functional adaptation of the TMJ was found to be more favorable for mandibular reduction and maxillary impaction than for mandibular advancement or combined upper and lower jaw procedures. Condylar path tracings were shown to represent a noninvasive technique to identify and monitor the functional status of the TMJ in response to surgical orthodontics.