Mandibular condylar hyperplasia is a disorder of unknown etiology characterized by persistent or accelerated growth of the condyle when growth should be slowing or ended (typically late adolescence or early adulthood). Growth eventually stops without treatment.
(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 and is generally asymptomatic except for appearance. 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.
Diagnosis of Mandibular Condylar Hyperplasia
Imaging (panoramic radiographs, cone beam CT, or conventional CT) to identify condylar enlargement and mandibular changes
Sometimes single-photon emission computed tomography (SPECT) or SPECT-CT with technetium-99m-labeled diphosphonates to assess for active growth
The diagnosis begins with a physical examination, focusing on progressive facial asymmetry, malocclusion, and deviation of the chin or dental midline.
On imaging to assess morphology, radiographs of the temporomandibular joint may appear normal, or the condyle may be proportionally enlarged and the mandibular neck elongated. Cone beam CT is usually performed 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.
To determine whether the condylar growth is active, SPECT or SPECT-CT with technetium-99m-labeled diphosphonates may be performed (1). Alternatively, serial clinical and radiographic follow-up may be used to confirm ongoing condylar growth.
Diagnosis reference
1. Beltran J, Zaror C, Moya MP, et al. Diagnosis and Treatment in Unilateral Condylar Hyperplasia. J Clin Med. 2023;12(3):1017. Published 2023 Jan 28. doi:10.3390/jcm12031017
Treatment of Mandibular Condylar Hyperplasia
During active growth, usually condylectomy
After growth cessation, orthodontics followed by surgical mandibular repositioning
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 improved by reducing the inferior border of the mandible.
