Three-Dimensional Facial Soft Tissue Changes After Orthognathic Surgery in Cleft Patients Using Artificial Intelligence-Assisted Landmark Autodigitization

The purpose of this study was to investigate three-dimensional facial soft tissue changes after bimaxillary orthognathic surgery (BOGS) in patients with cleft lip and palate. The samples consisted of 34 Korean young adult patients with skeletal class III malocclusion who underwent BOGS for maxillary advancement/posterior impaction and mandibular setback. They were divided into cleft-class III (C-CIII) group (n = 18) and noncleft-class III (NC-CIII) group (n = 16). Three-dimensional computed tomography images were taken 1 month before (T1) and 3 months after (T2) surgery. After 34 hard/soft tissue landmarks were automatically identified using software, the amount and direction of change in landmarks and the amount of change in 16 soft tissue variables during T1-T2 were calculated. Then, statistical analysis was performed. Compared to NC-CIII group, C-CIII group showed more posteriorly-positioned hard/soft tissue landmarks, larger alar width, alar base width and philtrum width, and more obtuse nasal tip angle at both T1 and T2 stages. C-CIII group exhibited higher soft-to-hard tissue movement ratios at the bottom of the nose (ΔSn/ΔANS, 1.08 versus 0.81) and the upper part of the upper lip (ΔPoint A'/ΔPoint A, 1.08 versus 0.91), but a lower ratio at the lower part of the upper lip (ΔLs'/ΔIs, 0.72 versus 1.01) than NC-CIII group. The number of hard-soft tissue landmarks with high correlation (>0.90) was smaller in C-CIII group than in NC-CIII group (2 versus 6). Scar tissues and abnormal muscles in the nose and upper lip might elicit different responses in the nasolabial soft tissues to BOGS between C-CIII and NC-CIII patients.