Induced condylar growth in a patient with hemifacial microsomia.

Hemifacial microsomia is a congenital abnormality which results in progressive, three-dimensional facial asymmetry in the growing child. Functional appliance therapy was instituted in an 11 year, 7 month old boy with hemifacial microsomia in order to determine if symmetry could be re-established by promoting masticatory muscle function on the affected side, thereby stimulating bone growth in the affected condyle over and above what would occur without any treatment intervention. Removable functional appliance therapy, and later, unilateral Herbst appliance therapy, produced a dramatic change in the condylar growth on the affected side. Herbst therapy has the advantage over a removable functional appliance in that patient acceptance is much greater. Lack of patient compliance may be the primary cause of the variable results obtained with functional appliances in hemifacial microsomia cases as reported in the literature.