• Maxillofacial Plastic and Reconstructive Surgery
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• 제34권3호
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• pp.180-185
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• 2012

Purpose: An accurate preoperative analysis of the patient is essential in orthognathic surgery in order to acquire superior results. In profile, the location of the chin's position may change according to the neck's inclination. This may ultimately affect the amount of surgical movement. During acquisition of cephalometric radiographs, or in supine position, there is a discrepancy in the neck's inclination. This means that there are also various discrepancies between the actual profile and the various preoperative profile images. In the clinical situation, the decision in performing genioplasty usually lies in the analysis of the patient's profile on the operating table at the final stages of orthognathic surgery. This study aims to analyze the different preoperative profile images and to compare their discrepancies. Methods: Fifty eight patients undergoing orthognathic surgery were chosen. These patients were divided into three groups according to angle's classification of malocclusion, as class I, II or III. The right profile of these patients in centric occlusion was taken in natural head position (NHP). This was set as the 'actual profile image.' Another right profile image was taken on the operating table after insertion of the nasotracheal intubation and with muscle relaxants in effect. This was also taken in centric occlusion. The angle (denoted 'A') between the soft tissue glabella-pognion and the true vertical plane was found in the above-mentioned profile images and in the cephalometric radiographs. The differences of these values were analyzed. Results: There were differences in Angle 'A' in all of the preoperative images. These values were however, not statistically significant. Conclusion: In order to gain an esthetic profile during orthognathic surgery, the NHP is shown to be the most reliable position. Images reproducing such head positions should be used in the treatment planning process.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제33권3호
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• pp.218-224
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• 2011

Purpose: The purpose of this study is to evaluate the post-operative skeletal stability after surgical correction of patients with mandibular prognathism by bilateral sagittal split ramus osteotomy (BSSRO) and to evaluate the horizontal relapse tendency after the surgery. Methods: Twenty-six patients with Class III dental and skeletal malocclusion were selected for this retrospective study. Fifteen of them underwent BSSRO for mandibular setback and eleven of them underwent two-jaw surgery (Lefort I and BSSRO). In each patient, lateral cephalometric radiographs were taken pre-operatively, post-operatively within 1 week, and post-operatively after eight months. After tracing of the cephalometric radiographs, various parameters were measured. The analyses were done by linear measurement to evaluate the change in position of hard tissue B point, pogonion and mandibular plan angle by examination on lateral cephalograms. Results: The horizontal relapse rate was 27.1% at B point and 31.6% at pogonion in patients who underwent BSSRO. The horizontal relapse rate of the group where the amount of correction exceeded 10 mm was 25.69% at B point. Conclusion: There were no statistical differences on the magnitude of setback and direction of rotation of the mandible in mandibular stability. There were also no statistical differences between single mandibular surgery and two-jaw surgery for mandibular stability.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제35권5호
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• pp.329-334
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• 2009

Objective: To evaluate the ratio between bone-contact length and inter-segmental length of the rigid fixation screw used in bilateral sagittal split ramus osteotomy (BSSRO) for mandibular setback. Material and Methods: Records of 40 patients with Class III malocclusion were selected. 20 of them had BSSRO, while the other 20 had BSSRO with maxillary LeFort I osteotomy. All of the patients had three noncompressive bicortical screws inserted at the gonial angle through transcutaneous approach. Two screws were inserted antero-posteriorly above inferior alveolar nerve and one screw was inserted below. The lengths of bone-contact and that of inter-segmental part were measured using cone-beam computed tomography. Ratio between these two measured lengths was calculated. Results: Both bone-contact and inter-segmental lengths were longer in BSSRO group than in BSSRO with maxillary LeFort I osteotomy group. Ratio of bone-contact to inter-segmental length was lower in BSSRO group than in BSSRO with Lefort I group. Both bone-contact and inter-segmental lengths were longer at the antero-superior position than at the inferior position. However, their ratio showed little difference. Conclusion: This study suggest that stability of screws in BSSRO group was greater than in BSSRO with Lefort I group. Stability of screws at the antero-superior position was greater than at the inferior position. Ratio of bone-contact to inter-segmental lengths was 0.2 in average.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제39권4호
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• pp.168-174
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• 2013

Objectives: The aim of this study is to investigate the correlation between 2-dimensional (2D) cephalometric measurement and 3-dimensional (3D) cone beam computed tomography (CBCT) measurement, and to evaluate the availability of 3D analysis for asymmetry patients. Materials and Methods: A total of Twenty-seven patients were evaluated for facial asymmetry by photograph and cephalometric radiograph, and CBCT. The 14 measurements values were evaluated and those for 2D and 3D were compared. The patients were classified into two groups. Patients in group 1 were evaluated for symmetry in the middle 1/3 of the face and asymmetry in the lower 1/3 of the face, and those in group 2 for asymmetry of both the middle and lower 1/3 of the face. Results: In group 1, significant differences were observed in nine values out of 14 values. Values included three from anteroposterior cephalometric radiograph measurement values (cant and both body height) and six from lateral cephalometric radiographs (both ramus length, both lateral ramal inclination, and both gonial angles). In group 2, comparison between 2D and 3D showed significant difference in 10 factors. Values included four from anteroposterior cephalometric radiograph measurement values (both maxillary height, both body height) and six from lateral cephalometric radiographs (both ramus length, both lateral ramal inclination, and both gonial angles). Conclusion: Information from 2D analysis was inaccurate in several measurements. Therefore, in asymmetry patients, 3D analysis is useful in diagnosis of asymmetry.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제34권4호
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• pp.252-259
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• 2012

Purpose: This study evaluated the postoperative stability of counter clockwise rotation of the mandibular plane in anterior openbite patients, who have had one jaw surgery performed. Methods: This study includes patients with skeletal class III malocclusion accompanied by anterior openbite among the patients who have had BSSRO performed, resulting in counter clockwise rotation of the mandibule. We excluded the patients with genioplasty and segmental surgery, and included 23 patients who underwent BSSRO. Results: We found no statistical significance between the amount of counter clockwise rotation in the mandible in the Pearson correlation test. Also, there was no significant difference between Group 1 (< $3^{\circ}$) and Group 2 (> $3^{\circ}$). Conclusion: This study evaluated the amount of horizontal relapse, and the degree of relapse. Stable results were obtained. Although there was no statistical significance between the degree of openbite and the amount of horizontal relapse, the group with a greater amount of openbite had a greater amount of relapse.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제41권5호
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• pp.224-231
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• 2015

Objectives: The purpose of this study was to evaluate changes in the pharyngeal airway space and hyoid bone position after mandibular setback surgery with bilateral sagittal split ramus osteotomy (BSSRO) and to analyze the correlation between the amount of mandibular setback and the amount of change in pharyngeal airway space or hyoid bone position. Materials and Methods: From January 2010 to February 2013, a total of 30 patients who were diagnosed with skeletal class III malocclusion and underwent the same surgery (BSSRO) and fixation method in the Division of Oral and Maxillofacial Surgery, Department of Dentistry at the Ajou University School of Medicine (Suwon, Korea) were included in this study. Lateral cephalograms of the 30 patients were assessed preoperatively (T1), immediately postoperatively (T2), and 6 months postoperatively (T3) to investigate the significance of changes by time and the correlation between the amount of mandibular setback and the amount of change in the airway space and hyoid bone position. Results: Three regions of the nasopharynx, oropharynx, and hypopharynx were measured and only the oropharynx showed a statistically significant decrease (P<0.01). A significant posterior and inferior displacement of the hyoid bone was found 6 months after surgery (P<0.01). Analysis of the correlation between the amount of mandibular setback and the amount of final change in the airway space and hyoid bone position with Pearson's correlation showed no significant correlation. Conclusion: In this study, the oropharynx significantly decreased after mandibular setback surgery, and changes in the surrounding structures were identified through posteroinferior movement of the hyoid bone during long-term follow-up. Therefore, postoperative obstructive sleep apnea should be considered in patients who plan to undergo mandibular setback surgery, and necessary modifications to the treatment plan should also be considered.

• 대한구순구개열학회지
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• 제12권2호
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• pp.85-94
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• 2009

Cleft lip and palate patients show midface hypoplasia, maxillary hypoplasia due to scar of previous surgery, and manifest as a class III malocclusion, retruded midface and shallow palate. These deformities have been treated with traditional orthognathic surgery. Although conventional Le Fort I osteotomy was performed on most cleft patinets with midface hypoplasia, it showed limited amount of maxillary advancement and high relapse tendency. Recently, when great amount of advancement are required in severe maxillary hypoplasia, distraction osteogenesis using RED system is widely used. But, several months of consolidation period is needed after distraction osteogenesis, occlusal relationship is not stable until mandibular setback surgery has done in mandibular hyperplasia cases and during these period, patients may feel discomfort. We present clinical cases of immediate rigid internal fixation after completion of maxillary distraction using RED system and simultaneous mandibular setback procedure in adult cleft and lip patients who show both maxillary hypoplasia and mandibular prognathism.

• Journal of Korean Dental Science
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• 제10권1호
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• pp.35-44
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• 2017

In case of loss of many teeth due to dental caries or periodontal disease, improvement of masticatory function and aesthetics can be obtained through implant treatment. However, if the patient does not have a normal intercondylar relationship, it is difficult to achieve an ideal occlusal relationship with only prosthetic treatment. In particular, oral reconstruction with orthodontic treatment or orthognathic surgery is necessary for patients with mandibular prognathism. However, if the posterior occlusion collapses due to severe caries or periodontal disease, orthognathic surgery may be difficult. The occlusal vertical stop is very important for the stability of the mandibular position during occlusal reconstruction through orthognathic surgery. The patient in this case had posterior occlusion collapsed due to the caries of a large number of posterior teeth, and showed mandibular prognathism and long face. We planned a full arch restoration with orthognathic surgery and extracted the hopeless teeth. To secure the vertical stop required for orthognathic surgery, the implant was placed before surgery. After the orthognathic surgery and the final prosthesis application, the results were satisfactory for the improvement of the aesthetics and the restoration of the masticatory function.

• 대한치과교정학회지
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• 제45권1호
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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.

• 대한치과교정학회지
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• 제50권2호
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• pp.129-135
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• 2020

Objective: This study aimed to evaluate the immediate effects of mandibular posterior displacement on the pharyngeal airway space (PAS) by using cephalometric evaluations and to investigate how the surrounding structures are schematically involved. Methods: In this retrospective study, 38 subjects with functional Class III malocclusion and two lateral cephalograms were selected. The first lateral cephalogram was taken with the mandible in the habitual occlusal position, and the second in anterior edge-to-edge bite. Paired t-test was used to analyze changes in the PAS, hyoid bone, tongue, and soft palate, followed by mandibular posterior displacement. Pearson's correlation analysis was used to determine the relationship between the amount of mandibular posterior displacement and other variables. Results: A statistically significant decrease was observed in the PAS following mandibular posterior displacement. Along with mandibular posterior displacement, the tongue decreased in length (p < 0.001) and increased in height (p < 0.05), while the soft palate increased in length, decreased in thickness, and was posteriorly displaced (p < 0.001). The hyoid bone was also posteriorly displaced (p < 0.05). There was no correlation between the amount of mandibular posterior displacement and the measured variables. Conclusions: The PAS showed a statistically significant decrease following mandibular posterior displacement, which was a consequence of retraction of the surrounding structures. However, there were individual variances between the amount of mandibular posterior displacement and the measured variables.