Three-dimensional analysis of soft and hard tissue changes after simultaneous 2-Jaw surgery in Class III patients: 1-year follow-up

Abstract

Introduction: This study investigated the correlation between the threedimensional changes in facial soft tissues, including the midfacial parasagittal area and maxillamandible complex, after Le Fort I osteotomy with maxillary posterior impaction and bilateral intraoral vertical ramus osteotomy (B-IVRO), using cone-beam computed tomography (CBCT). Material and Methods: This retrospective study included 22 skeletal Class III patients who underwent orthognathic surgery. Threedimensional CBCT images taken before and 1year after surgery were superimposed based on the cranial base. Midfacial soft tissues, including those in the parasagittal area and midsagittal areas of the face, were evaluated using reconstructed CBCT images. The study variables were analyzed using paired t-tests and Pearson’s correlation coefficient, and the ratios between soft tissue and hard tissue movement were calculated. Results: After surgery, the paranasal area moved forward with a ratio of 0.5, according to vertical movement of B. The upper lip and M U1 showed correlation in the sagittal axis with a ratio of 0.8. The lower lip and M L1 were correlated in the sagittal and vertical axis in a ratio of 1.12 and 0.84, respectively. B′, Pog′, Me′ had a ratio of 0.81.1 with their paired hard tissue landmarks for all axes. Conclusion: Orthognathic surgery using Le Fort I maxillary posterior impaction with B-IVRO mandibular setback results in forward movement of midfacial soft tissues, even though forward movement of the maxilla is limited because vertical movement of the maxillamandible complex causes redundancy of soft tissue and facial muscle and pulling from the retaining ligaments. This midfacial soft tissue change with maxillary posterior impaction could be advantageous to patients who have paranasal depression and protrusion of the upper lip due to proclined upper incisors, which are prevalent among Asian Class III patients.