Original article
Facial soft-tissue changes in skeletal Class III orthognathic surgery patients analyzed with 3-dimensional laser scanning

https://doi.org/10.1016/j.ajodo.2010.02.022Get rights and content

Introduction

Patients undergoing orthognathic surgery show considerable changes in both hard and soft tissues. The purpose of this study was to use a 3-dimensional (3D) laser scanner to evaluate the soft-tissue changes after the correction of skeletal Class III malocclusions with orthognathic surgery.

Methods

The subjects consisted of 20 Korean patients with skeletal Class III malocclusion who underwent LeFort I osteotomy with maxillary advancement and posterior nasal spine impaction, along with bilateral intraoral vertical ramus osteotomy for mandibular setback. Ten patients (group 1) had 2-jaw surgery with genioplasty, and the other 10 (group 2) had 2-jaw surgery without genioplasty. Three-dimensional images of the patients were acquired with a 3D laser scanner. The ratios of soft-tissue changes to hard-tissue movements were analyzed and compared between the 2 groups. In addition, the changes in the soft-tissue landmarks in the 3D coordinates and the 3D linear, angular, and proportional changes were measured preoperatively and postoperatively, and compared.

Results

There was no significant difference between the groups in the horizontal ratios of the soft-tissue to hard-tissue changes. In both groups, the ratios of the horizontal changes in the paranasal area were higher than in the subnasale area. There were more changes in the subalar area than in the supracommissural area, and more changes in the chin and labiomental areas than in the subcommissural area. Ala moved anterolaterally, and cheilion moved posteroinferiorly. The distance between upper-lip point and cheilion increased significantly (P <0.05). In the 3D angles, transverse nasal prominence and transverse upper lip prominence increased significantly (P <0.05).

Conclusions

The 3D analysis in this study can be used to estimate the soft-tissue changes in Class III patients who undergo orthognathic surgery.

Section snippets

Material and methods

Twenty skeletal Class III patients who underwent LeFort I osteotomy with maxillary advancement, posterior nasal spine impaction, and bilateral intraoral vertical ramus osteotomy with mandibular set back were enrolled in this study. Ten patients (group 1) underwent 2-jaw surgery with genioplasty, and the other 10 (group 2) had 2-jaw surgery without genioplasty. The amount of maxillary advancement and impaction was limited to 1.0 to 3.0 mm in each patient. No patient had severe facial asymmetry,

Results

Table I shows the hard-tissue and soft-tissue changes in the horizontal plane in groups 1 and 2. The amounts of Pog and Me movement in group 1 were relatively smaller than those in group 2 because of the genioplasty advancement. In the vertical changes, Ls and Li moved downward, even though almost all soft-tissue and hard-tissue landmarks moved upward (Table II). There were more changes in the subalar area than in the supracommissural area, and more changes in the chin and labiomental areas

Discussion

Among the many 3D capturing instruments currently used in the orthodontic studies, we used the 3D laser scanner Vivid 900, which has been reported to have a range of clinical error of 0.5 to 1.0 mm and a permissible accuracy for clinical use.14, 16, 17 The soft-tissue landmarks in this study proved to be reproducible and easy to designate by Baik et al,14 and have been used for facial soft-tissue analysis of Korean adults with normal occlusion.15 Unlike the hard tissues, the facial soft tissues

Conclusions

The movements of soft tissues in the various areas of the face showed no significant differences in the horizontal ratios between the 2 groups. There were more soft-tissue changes in the central parts of the face than in the lateral parts. The distance between ULP and Ch increased, with the soft tissue stretching after maxillary advancement and mandibular setback.

Overall, the quantitative analysis in this study can be used to estimate soft-tissue changes in Class III patients who undergo

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    The authors report no commercial, proprietary, or financial interest in the products or companies described in this article.

    Supported by the College of Dentistry (2005) and the Institute of Craniofacial Deformity of Yonsei University, Seoul, Korea.

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    Copyright © 2010 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.