Functional and morphometric outcome of adaptable slicing condylectomy in transverse condylar hyperplasia: A deep learning-enhanced 3D study.

BACKGROUND: Unilateral condylar hyperplasia (UCH) with transverse mandibular deviation is a frequent cause of facial asymmetry and skeletal Class III malocclusion. Adaptive slice condylectomy (ASC) has been proposed as a focused alternative to bimaxillary orthognathic surgery (OS), aiming to recenter the dental midline without bilateral skeletal osteotomies. We evaluated morphological and functional outcomes after SC using AI-assisted 3D analysis. MATERIALS AND METHODS: This retrospective cohort comprised 55 patients with transverse UCH treated between 2011 and 2024 at a single maxillofacial unit: 36 underwent unilateral ASC and 19 received bimaxillary OS. Cone-beam CT (CBCT) scans at baseline (T0) and 12 months (T1) were processed in 3D Slicer using a pretrained MONAI 3D U-Net for segmentation. Rigid cranial-base registration aligned T1 to T0. Metrics included condylar head volume, mean bone density, center displacement (ΔX/ΔY/ΔZ; |Δ|), and orientation change (axis-axis angle and yaw/pitch/roll). Postoperatively, the operated condyle was compared with the mirrored contralateral healthy side. RESULTS: ASC produced a predominantly lateral-superior repositioning of the treated condyle with midline correction. The contralateral condyle showed small adaptive shifts with overall morphologic stability. Mean postoperative asymmetry versus the mirrored side was 0.35 mm; the healthy side varied minimally (mean -0.32 mm), with deviations >1.5 mm confined to posteromedial sectors. No TMJ dysfunction occurred after ASC. Relative to OS, ASC was associated with shorter operative time (-80 min), reduced length of stay (-0.5 days), and fewer complications. CONCLUSION: Adaptive slice condylectomy is a safe and effective unilateral option for transverse UCH with III class, achieving functional correction and symmetry targets without routine bimaxillary osteotomies. The results are so good that we applied this procedure instead of bilateral sagittal split osteotomy (BSSO) in all patients with classes III and asymmetry adding, if necessary, Le Fort I surgery (advancement, canting correction, surgically assisted rapid palatal expansion-SARPE).