Facial asymmetry in Unilateral Condylar Hyperplasia: comparing treatment for active versus burnt out disease.

BACKGROUND Facial asymmetry due to unilateral condylar hyperplasia (UCH) requires treatment to address facial and occlusal imbalances. There is no definitive evidence to suggest that a single intervention strategy (during either active condylar overgrowth or the burnt-out phase) results in better / more symmetric correction. This study sought to quantify pre- and post-operative facial asymmetry in UCH patients comparing treatment for active versus burnt out disease. METHODS Pre- and post-operative three-dimensional (3D) photographs were obtained. Images were compared to unaffected controls as a standard for normal facial symmetry. Facial asymmetry was assessed using root mean squared deviation (RMSD). Paired student's t-tests were performed to compare the RMSDs of pre- and post-operative images between the UCH groups and against controls. RESULTS Forty patients were included (11 active, 9 burnt-out, and 20 controls) and 60 3D images were evaluated. Pre-operatively, patients in the burnt-out group had worse asymmetry than those with active UCH (p = 0.011). Both groups demonstrated significantly improved symmetry post-operatively (active; p = 0.0069 and burnt out; p = 1.74E-4). However, burnt out patients remained with some residual asymmetry (p = 4.75E-4), while their active counterparts showed no significant difference compared to unaffected controls (p = 0.089). CONCLUSION Patients with end-stage UCH have more severe facial asymmetry that is more difficult to normalize, compared to earlier intervention during active UCH. These findings suggest that, if possible, corrective intervention is preferable during active UCH.