Hemimandibular hyperplasia: a rare case of vertical facial asymmetry. A case report.

Background: Hemimandibular hyperplasia (HH), also known as hemimandibular hypertrophy, is characterised by excessive unilateral three-dimensional growth of the mandible after birth. Vertical elongation of the mandible on one side becomes clinically evident as a rare form of vertical facial asymmetry. Aberrant growth of the facial skeleton affects the developing dentition and dental compensation is usually unable to maintain optimal occlusal relationships. The resulting malocclusion is best managed surgically to address the various facial, skeletal and dental problems that confront clinicians.
Aim: To present a case of hemimandibular hyperplasia treated using a combined surgical-orthodontic approach.
Methods: Combined surgical-orthodontic treatment was accomplished in four phases: 1) presurgical orthodontic, 2) surgical, 3) post-surgical orthodontic and 4) orthodontic retention. Comprehensive records (including photographs, study models and radiographs) were taken at the pre-treatment, pre-surgery and debanding stages of treatment.
Results: A significant improvement in facial symmetry and a positive occlusal outcome were achieved. A more balanced gingival display has improved the patient's smile aesthetics.
Conclusion: Hemimandibular hyperplasia is a rare condition causing vertical facial asymmetry and a resulting malocclusion. A combined surgical-orthodontic approach is able to accomplish sound facial, skeletal and dental treatment outcomes.