Evaluation of Condylar Resorption Before and After Orthognathic Surgery

Malpositioned condyles during osteotomy can cause remodeling of the condyles, but can also initiate condylar resorption (CR). The radiological signs of CR are similar to juvenile osteoarthritis and osteoarthrosis. In the 1980s, conventional transcranial and infracranial radiographs were used to evaluate the position of the condyle in the fossa. An orthopantomogram can be used to describe the contour or morphology of the condyles, but it is not applicable for measurements. Magnetic resonance imaging is useful in evaluation of the disks, condyles, and synovia. Both conventional multislice computed tomography and cone-beam computed tomography (CBCT) can provide an excellent visualization of the condyles in 3 planes. With CBCT, condylar position and condylar changes can be assessed as a color-coded map, or as mesh transparencies, which provide higher accuracy. The pretreatment assessment of past or potential temporomandibular joint (TMJ) issues consists of a detailed history of previous TMJ symptoms, as well as a clinical and radiological examination. An orthopantomogram is helpful to make a risk profile based on the contour of a condyle and the stage of osteoarthritic degeneration. After orthognathic surgery, the surgeon must be aware of TMJ dysfunction symptoms, occlusal relapse, reduction of form and volume of the condyle, and loss of mandibular ramus height. In patients with a high risk for CR or when a suspicion of CR occurs, a CBCT is indicated. The incorporation of an automated postscan image enhancement protocol and subsequent 3-dimensional rendering of condyles into the 3-dimensional virtual head model of patients will provide a powerful tool for analysis of CR. (Semin Orthod 2013;19: 106-115.) (C) 2013 Elsevier Inc. All rights reserved.