Mandibular Condylar Resorption

Mandibular Condylar Underdevelopment- Resorption Conditions

Articular Disc Dislocation

The most common TMJ pathology associated with dentofacial deformity is an anterior and/or medially displaced articular disc. This condition can initiate a cascade of events leading to arthritis and TMJ related symptoms.  An MRI will show direction of disc displacement; progression of degeneration, mobility of joint components, etc. Simultaneous surgical treatment could include; reposition the TMJ disc into a normal anatomical, functional position and stabilize it using the Mitek anchor technique and required orthognathic surgical procedures to obtain optimal functional and esthetic outcomes. For disc stabilization, two 0-Ethibond sutures (Ethicon Inc., Somerville, NJ) are threaded through the Mitek anchor islet and the anchor is placed into the posterior head of the condyle lateral to the mid-sagittal plane and approximately 8 mm below the crown of the condyle. The sutures are used as artificial ligaments to secure and stabilize the disc to the condylar head. The indicated orthognathic surgery is then performed at the same operation to correct the associated dentofacial deformity, or it can be delayed and performed at a secondary surgical stage.

In our studies using the criteria of incisal opening greater than 35 mm, stable skeletal and occlusal relationships, and significant reduction in pain, the success rate was 91%.  The success rate was significantly better (95%) if the TMJ discs were surgically repositioned within the first 4 years of onset of the TMJ dysfunction without polyarthritic conditions.  After 4 years, the progression of irreversible TMJ degenerative changes may result in a lower success rate.  Significant degeneration of the TMJ may require total joint prostheses.

In patients with good facial balance, Class I occlusion, but with anteriorly displaced articular discs, repositioning the discs usually creates a malocclusion with end-on incisors relation and end-on Class III occlusion as well as posterior open bites. This occlusal change occurs because with displaced discs, the superior and posterior joint spaces decrease and the disc commonly thickens the longer it is displaced.  Therefore, when the disc is repositioned, the condyle is displaced downward and forward affecting the occlusal and skeletal relationship displacing the mandible toward an end-on Class III position.  For patients who originally had a Class I occlusion, mandibular ramus sagittal split osteotomies may be required at the same operation to maintain the original occlusion and create space between the condyles and fossas to accommodate the repositioned discs.