• The korean journal of orthodontics
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• v.38 no.1
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• pp.41-51
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• 2008

Objective: The aim of this study was to compare the initial lateral cephalometric characteristics in two groups of patients: those that had mandibular setback surgery only and those that had mandibular setback surgery with advancement genioplasty. Methods: The lateral cephalograms of thirty-one patients were studied. Twenty-one Class III patients (group A) had only madibular setback surgery Twelve Class III patients (group B) had mandibular setback surgery with advancement genioplasty. Results: Differences between two groups were found in N-Me, ANS-Me, Occlusal Plane angle, Palatal Plane to U1, Mandibular Plane to L1, Mandibular Plane to L6, SN to U1, Sn-Stms, and Pog' projection. Compared to group A, group B showed more linguoversion and extrusion of upper incisors, more extrusion of lower incisors and lower first molar, and more steepness of the occlusal plane. N-Me, ANS-Me, and Sn-Stms were also longer in group B. But Pog' projection was shorter than group A. Conclusion: We conclude that certain initial lateral cephalometric characteristics may help indicate the inclusion of advancement genioplasty when mandibular setback surgery is planned in skeletal Class III patients.

• The korean journal of orthodontics
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• v.39 no.1
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• pp.36-42
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• 2009

Objective: The purposes of this study were to provide an epidemiologic data base related to the orthodontic treatment need and to know the changing trends about treatment modality of private orthodontic clinics. Methods: Distribution, trends and orthodontic treatment plan of malocclusion patients were investigated in 1,620 consecutive patients who had been visited and examined in 4 private orthodontic clinics located in Seoul from 2003-2006. Results: Percentage of male and female patients was 26.9% and 73.1% respectively Age distribution had shown that percentage of the patients above 13 years was 78.9%, and above 19 years was 59.0%. Average age of whole patients was 20.5 years. With regard to Angle classification, each percentage of Class I, Class II division 1, Class II division 2 and Class III malocclusion was 38.9%, 34.8%, 2.3% and 24.0%. The percentage of extraction cases(00.9%) outnumbered nonextraction cases(39.1%) and 46% of extraction cases were upper and lower 1st premolar extraction cases. Patients who had chose treatment with fixed appliance and orthognathic surgery was 10.2%. Conclusions: Because the high percentage of adult, Class II malocclusion and orthognathic surgery cases in patients of private orthodontic clinics were shown in this study, orthodontic education program and national health policy in Korea need reformation.

• The korean journal of orthodontics
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• v.50 no.5
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• pp.324-335
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• 2020

Objective: To compare postoperative positional changes in the mandibular proximal segment between the conventional orthognathic surgery (CS) and the surgery-first approach (SF) using intraoral vertical ramus osteotomy (IVRO) in patients with Class III malocclusion. Methods: Thirty-eight patients with skeletal Class III malocclusion who underwent bimaxillary surgery were divided into two groups according to the use of preoperative orthodontic treatment: CS group (n = 18) and SF group (n = 20). Skeletal changes in both groups were measured using computed tomography before (T0), 2 days after (T1), and 1 year after (T2) the surgery. Three-dimensional (3D) angular changes in the mandibular proximal segment, condylar position, and maxillomandibular landmarks were assessed. Results: The mean amounts of mandibular setback and maxillary posterior impaction were similar in both groups. At T2, the posterior portion of the mandible moved upward in both groups. In the SF group, the anterior portion of the mandible moved upward by a mean distance of 0.9 ± 1.0 mm, which was statistically significant (p < 0.001). There were significant between-group differences in occlusal changes (p < 0.001) as well as in overjet and overbite. However, there were no significant between-group differences in proximal segment variables. Conclusions: Despite postoperative occlusal changes, positional changes in the mandibular proximal segment and the position of the condyles were similar between CS and SF, which suggested that SF using IVRO achieved satisfactory postoperative stability. If active physiotherapy is conducted, the proximal segment can be adapted in the physiological position regardless of the occlusal changes.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.29 no.3
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• pp.191-194
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• 2003

Macroglossia can cause dentomusculoskeletal deformities, instability of orthodontic and orthognathic surgical treatment, and create masticatory, speech and airway management problems. To determine whether a reduction glossectomy is necessary, it will important to identify the signs and symptoms of macroglossia. Development of dentoskeletal changes directly related with tongue size, such as an anterior open bite or a Angle Class III malocclusion tendency, would indicate that reduction glossectomy may be beneficial. For reduction glossectomy, several techniques have been reported. However, in most techniques the tip of tongue is removed. So its excision causes the loss of most mobile and sensitive portion of the tongue, and creates ankylosed, globular tongue. To avoid such problems, central tongue reduction technique have been proposed. This article will introduce central tongue reduction for anterior openbite case associated with macroglossia.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.40
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• pp.13.1-13.8
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• 2018

Background: We evaluated change in the mandibular condyle after orthognathic surgery using cone-beam computed tomography (CBCT) in patients with facial asymmetry. Methods: Thirty patients with skeletal class III malocclusion and mandibular prognathism or facial asymmetry were classified into two groups according to the amount of menton deviation (MD) from the facial midline on anteroposterior (AP) cephalogram: group A (asymmetry, MD ≥ 4 mm; n = 15) and group B (symmetry, MD < 4 mm; n = 15). Position and angle of condylar heads on the axial, sagittal, and coronal views were measured within 1 month preoperatively (T0) and postoperatively (T1) and 6 months (T2) postoperatively. Results: On axial view, both groups showed inward rotation of condylar heads at T1, but at T2, the change was gradually removed and the condylar head returned to its original position. At T1, both groups showed no AP condylar head changes on sagittal view, although downward movement of the condylar heads occurred. Then, at T2, the condylar heads tended to return to their original position. The change in distance between the two condylar heads showed that they had moved outward in both groups, causing an increase in the width between the two heads postoperatively. Analysis of all three-dimensional changes of the condylar head positions demonstrated statistically significant changes in the three different CBCT views in group B and no statistically significant changes in group A. Conclusions: There was no significant difference between the two groups in condylar head position. Because sagittal split ramus osteotomy can be performed without significant change in symmetrical and asymmetrical cases, it can be regarded as an effective method to stabilize the condylar head position in patients with skeletal class III malocclusion and mandibular prognathism or facial asymmetry.

• Imaging Science in Dentistry
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• v.50 no.2
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• pp.105-115
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• 2020

Purpose: This study investigated the position of the hyoid bone and its relationship with airway dimensions in different skeletal malocclusion classes using cone-beam computed tomography (CBCT). Materials and Methods: CBCT scans of 180 participants were categorized based on the A point-nasion-B point angle into class I, class II, and class III malocclusions. Eight linear and 2 angular hyoid parameters(H-C3, H-EB, H-PNS, H-Me, H-X, H-Y, H-[C3-Me], C3-Me, H-S-Ba, and H-N-S) were measured. A 3-dimensional airway model was designed to measure the minimum cross-sectional area, volume, and total and upper airway length. The mean crosssectional area, morphology, and location of the airway were also evaluated. Data were analyzed using analysis of variance and the Pearson correlation test, with P values <0.05 indicating statistical significance. Results: The mean airway volume differed significantly among the malocclusion classes(P<0.05). The smallest and largest volumes were noted in class II (2107.8±844.7 ㎣) and class III (2826.6±2505.3 ㎣), respectively. The means of most hyoid parameters (C3-Me, C3-H, H-Eb, H-Me, H-S-Ba, H-N-S, and H-PNS) differed significantly among the malocclusion classes. In all classes, H-Eb was correlated with the minimum cross-sectional area and airway morphology, and H-PNS was correlated with total airway length. A significant correlation was also noted between H-Y and total airway length in class II and III malocclusions and between H-Y and upper airway length in class I malocclusions. Conclusion: The position of the hyoid bone was associated with airway dimensions and should be considered during orthognathic surgery due to the risk of airway obstruction.

• The korean journal of orthodontics
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• v.45 no.1
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• pp.3-12
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• 2015

Objective: We compared the skeletal and dental changes that resulted from the use of two methods of intermaxillary fixation (IMF)-miniscrews and surgical archwire-in 74 adult patients who had Class III malocclusion and were treated with the same orthognathic surgical procedure at a hospital in Korea. Methods: All the patients underwent Le Fort I osteotomy and bilateral sagittal split ramus osteotomy with rigid fixation. They were divided into two groups according to the type of IMF used-group 1 underwent surgical archwire fixation and group 2 underwent orthodontic miniscrew fixation. In a series of cephalograms for each patient, we compared vertical and horizontal tooth-position measurements: (a) immediately after surgery ($T_0$), (b) 3 months after surgery ($T_1$), and (c) 6 months after surgery ($T_2$). Cephalometric changes within each group were examined using one-way analysis of variance (ANOVA) while the independent samples t -test procedure was used to compare the two groups. Results: After surgery, the maxillary incisors tended to be proclined in both groups although there were no significant differences. Incisor overbite increased significantly in both groups from $T_0$ to $T_1$, and the miniscrew group (group 2) showed slightly greater overbite than the archwire group (group 1). Conclusions: This study suggest that the use of orthodontic miniscrews and orthodontic surgical archwire for IMF in adult patients results in similar skeletal and dental changes.

• The korean journal of orthodontics
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• v.43 no.6
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• pp.263-270
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• 2013

Objective: To evaluate condylar head remodeling after mandibular set-back sagittal split ramus osteotomy (SSRO) with rigid fixation in skeletal class III deformities. The correlation between condylar head remodeling and condylar axis changes was determined using cone-beam computed tomography (CBCT) superimposition. Methods: The CBCT data of 22 subjects (9 men and 13 women) who had undergone mandibular set-back SSRO with rigid fixation were analyzed. Changes in the condylar head measurements and the distribution of the signs of condylar head remodeling were evaluated by CBCT superimposition. Results: The subjects showed inward rotation of the axial condylar angle; reduced condylar heights on the sagittal and coronal planes; and resorptive remodeling in the anterior and superior areas on the sagittal plane, superior and lateral areas on the coronal plane, and anterior-middle and anterior-lateral areas on the axial plane (p < 0.05). Conclusions: The CBCT superimposition method showed condylar head remodeling after mandibular set-back SSRO with rigid fixation. In skeletal class III patients, SSRO with rigid fixation resulted in rotation, diminution, and remodeling of the condylar head. However, these changes did not produce clinical signs or symptoms of temporomandibular disorders.

• Imaging Science in Dentistry
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• v.40 no.2
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• pp.75-81
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• 2010

Purpose : This study is aimed to evaluate the position of mandibular foramen of mandibula prognathism patients using 3-dimensional CT images in order to reduce the chance of an anesthetic failure of the mandibular nerve and to prevent the damage to the inferior alveolar nerve during the orthognathic surgery. Materials and Methods : The control group consist of 30 patients with class I occlusion. The experimental group consist of 44 patients with class III malocclusion. Three-dimensional computed tomography was used to evaluate the position of the mandibular foramina. Results : The distance between mandibular plane and mandibular foramen, class I was 25.385 mm, class III was 23.628 mm. About the distance between occlusal plane and mandibular foramen, class I was 1.478 mm, class III was 5.144 mm. The distance between posterior border plan of mandibular ramus and mandibular foramen had not statistically significant. About the distance between sagittal plane of mandible and mandibular foramen did not also showed statistically significant. Conclusion : The result of this study could help the clinicians to apprehend more accurate anatomical locations of the foramina on the mandible with various facial skeletal types. thereby to perform more accurate block anesthesia of the mandibular nerve and osteotomy with minimal nerve damage. In addition, this study could provide fundamental data for any related researches about the location of the mandibular foramina for other purposes.

• The korean journal of orthodontics
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• v.40 no.3
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• pp.145-155
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• 2010

Objective: Lateral cephalometric radiographs have been the main form of resource for assessing two dimensional anteroposterior airway changes. The purpose of this study was to evaluate the three dimensional volumetric change in the upper airway space in Class III malocclusion patients who underwent mandibular setback surgery. Methods: Three dimensional cone-beam computed tomographs (CBCT) and their three dimensional reconstruction images were analyzed. The samples consisted of 20 adult patients (12 males and 8 females) who were diagnosed as skeletal Class III and underwent mandibular setback surgery. CBCTs were taken at 3 stages - Baseline (1.8 weeks before surgery), T1 (2.3 months after surgery), and T2 (1 year after surgery). Pharyngeal airway was separated according to the reference planes and reconstructed into the nasopharynx, the oropharynx and the hypopharynx. Measurements at Baseline, T1, and T2 were compared between groups. Results: The result showed the volume of the pharyngeal airway decreased significantly 2.3 months after surgery (p < 0.001) and the diminished airway did not recover after 1 year post-surgery. The oropharynx was the most decreased area. Conclusions: These findings suggest that mandibular setback surgery causes both short-term and long-term decrease in the upper airway space.