Morphological Profiling of Unilateral Condylar Hyperplasia: Implications for Surgical Decision-Making

Unilateral condylar hyperplasia (UCH) presents challenges with functional and esthetic concerns, including facial and chin asymmetry, prognathism, class III malocclusion, and temporomandibular joint symptoms. This study aims to precisely locate condylar and mandibular asymmetry in patients with UCH, aiding targeted surgical correction and addressing persistent skeletal changes.

This retrospective study analyzed data from patients with UCH and controls, utilizing high-quality cone beam computed tomography scans with 1 mm or fewer slices. Morphometric points were placed using Planmeca software, measuring linear distances on both affected and unaffected sides.

In a cohort of 40 patients (29 UCH, 11 controls), significant differences in condylar head and neck lengths were observed between the affected and unaffected sides in patients with UCH ( P = 0.0019). However, ramus length showed no significant variation ( P = 0.65). When comparing differences in condylar head and neck length between controls and patients with UCH, a substantial contrast was evident ( P = 1.98e-07), while ramus length differences were not significant ( P = 1.00). The median condylar head and neck lengths were 20.3 mm for controls, 19.78 mm for the unaffected side in patients with UCH, and 23.48 mm for the affected side.

Facial asymmetry in UCH primarily results from differences in condylar head and neck length, not ramus length. This emphasizes the importance of high condylectomy in addition to bilateral sagittal split osteotomy to achieve improved symmetry and reduced temporomandibular joint dysfunction. Understanding these regional skeletal changes is critical for effective UCH treatment.