The outcome of skeletofacial reconstruction with mandibular rotation for management of asymmetric skeletal class III deformity: A three-dimensional computer-assisted investigation

Ting-Yu Wu,Lun-Jou Lo,Hsiu-Hsia Lin,Cheng-Ting Ho,Rafael Denadai

doi:10.1038/s41598-019-49946-9

Ting-Yu Wu, Lun-Jou Lo + Show 3 more

Open Access

https://doi.org/10.1038/s41598-019-49946-9

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Abstract

The mandibular proximal ramus segments should be moved and rotated during orthognathic surgery-based skeletofacial reconstruction for the correction of challenging patients with facial asymmetry and malocclusion, but quantitative data regarding this rotation were not sufficient to date. This 3D computer-assisted study measured the proximal ramus segment rotation after 3D simulation-guided two-jaw surgery in patients with facial asymmetric deformity and class III malocclusion (n = 31). Using 3D mandible models and a reliable proximal ramus segment-related plane, angular changes in pitch, roll and yaw directions were measured before and one month after surgery. Significant rotational changes (p < 0.01) were observed in the left and right sides and overall proximal ramus segments after surgery, with absolute differences of 4.1 ± 3.0 (range −7.8 to 6.9), 2.8 ± 2.3 (−8.8 to 5.0), and 2.7 ± 2.4 (−6.6 to 9.9) degrees in pitch, roll, and yaw rotations, respectively. Numbness and mouth opening limiting occurred within the first 6 months after surgery but the patients had an unremarkable long-term postoperative course, with no revisionary surgery required. This study contributes to the multidisciplinary-related literature by revealing that proximal ramus segment rotation and rigid fixation with no postoperative intermaxillary immobilization was practicable in skeletofacial surgery for the successful treatment of asymmetric deformity and class III malocclusion.

Highlights

Skeletofacial surgery is an effective procedure for patients with challenging cases of facial asymmetry and malocclusion[1,2,3,4]
Using the bilateral sagittal split osteotomy (BSSO) technique, the proximal ramus segment should be rotated in the three potential directions to achieve a symmetric and balanced face, with center of rotation at the condyle
Others have reported the use of the intraoral vertical ramus osteotomy (IVRO) technique but requiring postoperative intermaxillary immobilization[14,15]

Summary

Introduction

Skeletofacial surgery is an effective procedure for patients with challenging cases of facial asymmetry and malocclusion[1,2,3,4]. The establishment of 3D technology-based quantitative data related to the rotation of the proximal ramus segment after surgery may provide helpful information for multidisciplinary teams (dentists, orthodontists, oral surgeons, maxillofacial surgeons, ear, nose and throat surgeons, head and neck surgeons, and plastic surgeons) in surgical planning and execution. The purpose of this 3D computer-assisted study is to measure the postoperative rotation of the proximal ramus segment in a sample of patients with facial deformity managed with two-jaw surgery, using the BSSO mandible setback technique with bicortical screws-based rigid fixation and no postoperative intermaxillary immobilization

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Results

Conclusion