Mandibular Condylar Hyperplasia
(See also Overview of Temporomandibular Disorders.)
Slowly progressive unilateral enlargement of the head and neck of the condyle causes crossbite malocclusion, facial asymmetry, and shifting of the midpoint of the chin toward the unaffected side. The patient may appear prognathic. The lower border of the mandible is often convex on the affected side. Chondroma and osteochondroma may cause similar symptoms and signs, but they grow more rapidly and may cause even greater asymmetric condylar enlargement.
On plain x-rays, the temporomandibular joint may appear normal, or the condyle may be proportionally enlarged and the mandibular neck elongated. Cone beam CT is usually done to determine whether bone growth is generalized, which confirms the diagnosis, or localized to a particular part of the condyle. If growth is localized, a biopsy may be necessary to distinguish between tumor and hyperplasia.
Treatment usually includes condylectomy during the period of active growth. If growth has stopped, orthodontics and surgical mandibular repositioning are indicated. If the height of the mandibular body is greatly increased, facial symmetry can be further improved by reducing the inferior border of the mandible.