Comprehensive three-dimensional morphological changes in perioral soft tissue following bimaxillary orthognathic surgery in patients with skeletal Class III malocclusion.

This study aimed to comprehensively evaluate the three-dimensional morphological changes in perioral soft tissue in patients with skeletal Class III malocclusion after combined orthognathic-orthodontic treatment. In total, 68 eligible patients with skeletal Class III malocclusion who underwent bimaxillary surgery and orthodontics between January 2019 and January 2023 were included. Cone-beam computed tomography data were collected for each patient at three stages: pre-treatment (T0), 1 week before surgery (T1), and on completion of treatment (T2). Perioral soft-tissue changes, including upper/lower lip vermilion thickness, alar width, and nasolabial and mentolabial angles, were measured via image reconstruction and 3D measurements using Dolphin Software. Upper/lower lip thickness increased after preoperative orthodontics (T0-T1), while decreased upper lip thickness and increased lower lip thickness were observed after orthognathic surgery (T1-T2) and the whole treatment (T0-T2). Increased alar width and nasolabial angle, along with decreased mentolabial angle, were observed after orthognathic surgery. Lip thickness significantly correlated with incisor inclination in both jaws. Alar width, alar base width, and nasolabial angle positively correlated with maxillary anteroposterior or vertical movement. Collectively, our results comprehensively delineate perioral soft-tissue changes in patients with skeletal Class III malocclusion following combined orthodontic-orthognathic surgery, and underscore the necessity of incorporating perioral soft-tissue changes into treatment planning.