Three-dimensional volumetric analysis of mandibular condyle changes in active growing condylar hyperplasia

Condylar hyperplasia is characterized by excessive mandibular condylar growth, causing progressive facial asymmetry and occlusal discrepancies. This study investigates the transition from active to inactive growth stages, a critical determinant for optimizing surgical timing and selecting appropriate intervals for corrective orthognathic surgery. A retrospective study was conducted involving 30 patients with unilateral condylar hyperplasia (mean age 21.90 ± 4.16 years) at a university hospital. Assessment of condylar hyperplasia involved measuring metabolic activity through bone scintigraphy, in conjunction with three-dimensional volumetric and height evaluations via computed tomography (CT). This approach enabled a comparative analysis between the affected and unaffected condylar sides during the growth phase transition. Results showed a median duration of 27.75 months (interquartile range 18.87 months) for this transition. Metabolic activity, as recorded by bone scintigraphy, declined from a mean tracer uptake difference of 14.02 ± 4.17% in the active stage to 4.42 ± 2.65% in the inactive stage. Additionally, the mean condylar volume significantly increased from 2230 ± 630 mm³ in the active stage to 2390 ± 650 mm in the inactive stage, reflecting a mean increase of 156 mm³ (P < 0.001). In contrast, changes in mean condylar height were not statistically significant (24.05 ± 3.74 mm to 24.51 ± 3.67 mm, P = 0.21). In conclusion, volumetric changes are significant during the transition to inactivity, while height changes are not. This study emphasizes the importance of volumetric assessments in guiding surgical timing and intervention strategies for condylar hyperplasia management.