片側性顔面短小症の未治療の成長期患者における下顎形態の評価：3Dコンピュータ断層撮影研究

Hemifacial Microsomia (HFM) is the second most common craniofacial malformation after clefts and it is characterized by mandibular hypoplasia and facial asymmetry. This retrospective study aimed to evaluate mandibular morphology in growing HFM patients using three-dimensional (3D) computed tomography (CBCT), focusing on volumetric asymmetries. A total of 26 patients aged 5-13 years with unilateral HFM were analyzed. They were stratified into two age groups (5-8 and 9-13 years) and classified according to Pruzansky-Kaban system in two severity categories (mild/severe deformity). CBCT data were processed to reconstruct 3D mandibular models, segmenting the condylar, coronoid and gonion regions. Volumetric differences between affected and unaffected sides were compared across age and severity subgroups. Results showed that all the three functional units were significantly smaller on the affected side, especially in severe HFM cases. However, no statistically significant differences were found between the two age groups, suggesting that mandibular asymmetry remains substantively unchanged over the two consecutive time points examined. Multivariable regression confirmed that HFM severity was strongly associated with condylar and gonial volume discrepancies. This study highlights the value of CBCT-based 3D reconstruction for precise assessment of mandibular morphology and supports its role in individualized diagnosis and treatment planning for HFM patients.