Challenges in unilateral condylar hyperplasia

Research output: PhD ThesisPhD-Thesis - Research and graduation internal


Unilateral condylar hyperplasia (UCH) is a progressive asymmetric disorder of the mandible due to condylar hyperactivity. It can be detected by SPECT(-CT) on top of clinical and radiological findings. The etiology is unknown. Different phenotypes are possible, and a classification is difficult. There is no evidence regarding etiology, classification and optimal treatment of UCH. In this thesis a critical evaluation of various classifications is presented, and a growth model is postulated in which a different vector of hyperactivity leads to a spectre of phenotypical deformities.
Quantitative analysis in UCH is useful for diagnosing, evaluating and treating the deformity. Quantification also facilitates decision making and timing of surgery. With 3D virtual soft tissue reconstruction, significant difference is identified in asymmetry between UCH patients and controls. Skeletal 3D- instead of 2D- quantification of the (3D) condition has proven to be useful and accurate. The most used classification in hemimandibular elongation (HE) and hemimandibular hyperplasia (HH) however does not fit these 3D findings. In this thesis, a method was introduced and validated for quantifying mandibular asymmetry, which can be used as an important tool for comparison among individuals and groups.
A partial condylectomy for active UCH patients is recommended as first treatment, and postoperative remodelling is observed in a period of 6 months. Second stage orthognathic surgery may be indicated in due time, but not for all UCH patients. A standardized assessment and a treatment algorithm is proposed.
Molecular studies demonstrate a mosaic variant in PIK3CA, highly suggestive to be causative for the overgrowth in a hemifacial hyperplasia (HFH) patient with concomitant signs of UCH. However, no causative variants could be detected in a series of solitary UCH patients, and the etiology remains unknown.
Future perspectives include the development of a dynamic growth model, developing an integrated ‘skeletal and soft tissue 3D quantitative tool’ that could be used for intra and inter population evaluation and more detailed (epigenetic) studies regarding etiology of UCH.
Original languageEnglish
Awarding Institution
  • University of Amsterdam
  • Becking, AG, Supervisor
  • Maal, T.J.J., Co-supervisor
Award date6 Nov 2019
Print ISBNs9789463325417
Publication statusPublished - 2019


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