• The korean journal of orthodontics
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• v.29 no.4 s.75
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• pp.503-510
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• 1999

The purpose of this study is to investigate the negative effects of cervical pull headgear and to compare the differences between the two groups of growers-vertical grower and horizontal grower group-which are classified by the posterior-anterior facial height ratio. Initial and final lateral cephalograms were taken for 26 patients including 15 vertical growers and 11 horizontal growers ; also, 3 angular measurements and 4 linear measurements were evaluated. The following results were found. 1. The palatal plane was tipped anteroinferiorly in the vertical grower group. 2. The posterior facial height/anterior facial height ratio was increased in the horizontal grower group. 3. The Mandibular plane angle remained stable on both groups. 4. There was no significant difference between the two groups in the amount of maxillary molar extrusion.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.28 no.1
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• pp.24-30
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• 2002

The facial patterns were expressed by the interrelation of variable factors such as heredity, function and environment. Such variable factors have an effect on the growth and development of maxillofacial bones. The malocclusions with skeletal discrepancies are caused by abnormal forms, sizes and positions of cranial base, maxilla and mandible. For the proper diagnosis and treatment planning, the analysis of such structures is necessary. Lateral cephalograms of 54 adults with class III malocclusion patients (test group) and 61 adults with normal occlusion (control group) were analyzed. Anteroposterior relations and sizes of cranial base, maxilla, mandible were estimated to compare with those of normal ones. In test group, the anterior cranial base length was within normal range, but posterior cranial base, maxilla and mandibular body were longer than those in control group, significantly. Based on the cranial base, the location of maxilla in test group was normal, but the location of mandible was more anterior than that in control. Based on the maxilla, the location of mandible was more anterior in test group than that in control. Both mandibular body and ramus anteroposterior lengths in test group were larger than those in control. Both mandibular plane angle and upper gonial angle were within normal range, but lower gonial angle was significantly high in test group.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.40 no.4
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• pp.160-168
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• 2014

Objectives: The purpose of this study was to evaluate the condylar position in relation to the glenoid fossa before and after orthodontic-orthognathic surgical treatment and to investigate the relationship with skeletal relapse. Materials and Methods: Lateral cephalograms and temporomandibular joint tomograms from 19 patients with mandibular prognathism who received orthodontic-orthognathic surgery were included in this study. Samples were divided into two groups based on skeletal change during the retention period. The relapse group consisted of 7 patients (3 females and 4 males; mean age, 21.9 years) whose pogonion or menton displaced more than 1 mm during the retention period and the stable group consisted of 12 patients (5 females and 7 males; mean age, 21.7 years). Anterior joint space, posterior joint space, superior joint space, and anteroposterior index were measured on tomograms at pretreatment and posttreatment timepoints. Condyle position and frequency of the positional change were compared between both groups. Results: In the relapse group and stable group, 42.9% and 45.8% of the condyles, respectively, showed forward or backward displacement at posttreatment. However, the changes were small and the mean anterior, posterior, superior joint spaces and frequencies of the positional changes did not differ statistically between both groups. Conclusion: Our results suggest that small positional changes of the condyle, which may occur after orthodontic-orthognathic surgery treatment, may not be related to skeletal relapse after removal of the orthodontic appliances.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.28 no.1
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• pp.27-34
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• 2006

After orthognathic surgery in skeletal class III patients, the hyoid bone position and the upper airway dimension could be changed due to mandibular setback. There has been many studies about airway dimension of the patients with skeletal class II malocclusion or obstructive sleep apnea. but not with skeletal class III. The purpose of this study was to examine the change of position of the hyoid bone and the consequent change of airway space as the result of retrusion of mandible after orthognathic surgery in skeletal Cl III malocclusion patients. It is also to apply this results in predicting, diagnosing and treating the subsequent obstructive sleep apnea. Forty patients who were diagnosed as skeletal Cl III maloccusion, received orthoganthic surgery of both jaws including mandibular setback, and were followed up post-operatively for more than 6 months were selected. There were 10 male patients 30 female patients. The preoperative and postoperative lateral cephalograms were traced and the distances and angles were measured. The nasopharyngeal space increased postoperatively while the oropharyngeal space decreased. Except for the change of oroparyngeal space, the changes in male patients were greater than female patients. The hyoid bone moved in the posterior-inferior direction, and the change was greater in males than in females. If the postoperative mandibular setback is great, then a significant decrease of airway space and posterior and inferior movement of the hyoid bone were observed. This can result in symptoms related to obstructive sleep apnea. This result should be considered in the diagnosis and treatment planning of orthognathic surgery patients.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.22 no.2
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• pp.174-183
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• 2000

This study was performed to investigate the characteristics of soft tissue profile of the class III malocclusion and to test the yardstick far differential diagnosis between surgical and orthodontic patients. Initial lateral cephalograms of orthodontic group(30 patients) that have acceptable occlusion and profile by orthodontic treatment alone and surgical group(30 patients) that have favorable occlusion and profile by combined surgical-orthodontic treatment were selected in Ajou university hospital. Powell and Burstone II analysis were made on the tracing. Descriptive, comparative, factor, cluster, and discriminant analysis were carried out with computer program. The results were as followings : 1. Patients who received surgery had a more concave profile and a longer lower facial height than patients who received orthodontic treatment alone. 2. Nasolabial angle, ratio of vertical height, and mentolabial sulcus were significantly different at the 5% level. And facial protuberance, upper lip protuberance, mentocervical angle, nasofrontal angle, nasomental angle, mandibular vertical height, angle between cervix and lower face, ratio of mandibular vertical height divided by cervical depth, ratio of vertical height between upper and lower lip, and maxillary protuberance were significantly different at the 1% level. 3. 8 factors were extracted and factor 2, 3, and 8 showed significant differences by factor analysis. 4. Orthodontic group (25) and surgical group (35) were classified by cluster analysis. 5. Discriminant function was D = 0.079Nasomental angle + 0.081Sn-Gn + 3.343Sn-Gn/C-Gn + 1.734Sn-St/St-Me' -26.460, and cutting score was 0, so we can discriminate that orthodontic group has the score above 0, and surgery group below 0. And 91.7% of original grouped cases were correctly classified.

• The korean journal of orthodontics
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• v.14 no.1
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• pp.15-24
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• 1984

The purpose of this study was to evaluate the effect of O.M.A on Angle's class III malocclusion. The author analysed the data obtained from pre- and post-treatment lateral cephalograms. The results obtained were as follows : 1. Forward growth of maxillary complex was accomplished. 2. The mandible showed few morphological changes in the presence of downward and backward swing. 3. It was assumed that the hooks attached to the intraoral appliance should be placed as far frontally as possibie. 4. Relations of the upper and lower jaws were improved resulting in better facial profiles.

• The korean journal of orthodontics
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• v.24 no.4 s.47
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• pp.787-798
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• 1994

The purpose of this study was three-fold: i) to investigate the degree of asymmetry in Angle's Class III malocclusion patients and normal adults; ii) to determine the nature of difference existed between two groups; and iii) to investigate the correlationship between the degree of asymmetry and ANB and overbite in Angle's Class III malocclusion patients. The subjects consisted of 25 Angle's Class III malocclusion patients and 25 normal adults and the mean ages were 22.0 and 24.5 years, respectively. Their posteroanterior and lateral cephalograms were traced and analysed with three-dimensional approach. The results were as follows: 1. Asymmetry of Angle's Class III malocclusion group was significant in all regions except cranial base. Their horizontal asymmetry was seen in mandibular angle, maxillary and mandibular 1st molar, mandibular midline and menton. Vertical asymmetry was observed in maxillary 1st molar and mandibular shape and anteroposterior asymmetry in mandibular angle. 2. Nine variables indicating asymmetry were selected and each variable had similar discriminant score. 3. There was a little correlationship between An and asymmetric variable(MSR-B6) and its correlation coefficients was 0.3564. 4. There was no significant correlationship between overbite and asymmetric variables.

• The korean journal of orthodontics
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• v.23 no.4 s.43
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• pp.693-705
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• 1993

The purpose of this study was to investigate the functional adaptation of the tongue, the hyoid bone, the digastric muscle and the upper airway and the variables predicting postoperative stability following orthognathic surgery in patients with mandibular prognathism. 18 patients were selected(8 men and 10 women) for this study, who had received orthognathic surgery. Their lateral cephalograms, those were taken preoperatively, immediate postoperatively and over 6 months follow-up, were traced and analysed. The results were as follows : 1. The downward displacement of the hyoid bone and extended head posture were recognized, right after operation. Statistically significant correlations were found between the changes of the mandibular position and the digastric muscle and the change of head posture during operation. 2. The tongue was displaced downward following the hyoid displacement postoperatively. Statistically significant correlations were found between the change of the mandibular position and the change of the distance of the tongue and hard palate, and between the change of head posture and the changes of the upper airway sizes, the digastric muscle and the hyoid position during over 6 month's follow-up. 3. The change of the distance of the tongue and hard palate was the most significant factor for prognosis during over 6 month's follow-up. 4. There were no variables before operation to predict the postoperative stability and the constriction of the upper airway.

• The korean journal of orthodontics
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• v.23 no.4 s.43
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• pp.707-724
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• 1993

The purpose of the study is to estimate hard and soft tissue changes after orthognathic surgery for the correction of the mandibular prognathism and to describe interrelationship and ratios of soft and hard tissue changes. The presurgical and postsurgical lateral cephalograms of 31 treated patients(17 males and 14 females) was used ; these patients had received combined orthodontic-surgical treatment by means of a bilateral sagittal split ramus osteotomy. Their ages ranged from 16 to 31 years and mean age was 21.4 years. A computerized cephalometric appraisal was developed and used to analyse linear and angular changes of skeletal and soft tissue profile. The statistical elaboration of the data was made by means of $SPSS/PC^+$. The results of the study were as follows : 1. The correlations of soft and hard tissue horizontal changes were significantly high and the ratios were $97\%$ at LI, $107\%$ at ILS, and $93\%$ at Pog'. 2. The correlations of vertical changes at Stm, LI and horizontal changes at Pog were high$(26\%)$ and at the other areas were not statistically high. 3. The correlations of soft ad hard tissue vertical changes were not significantly high in all areas except Gn' $(30\%)$ and Me' $(56\%)$. 4. The soft tissue thickness was significantly decreased in upper lip and increased in lower lip, and the amount of changes after surgery was reversely correlated with initial thickness. 5. The facial convexity was increased and relative protrusion of upper lip was increased and that of lower lip was decreased. 6. The upper to lower facial height(Gl-Sn/Sn-Me') was increased and upper to lower jaw height(Sn-Stms/Stmi-Me') was increased.

• The korean journal of orthodontics
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• v.45 no.4
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• pp.171-179
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• 2015

Objective: To compare dentoalveolar and skeletal changes produced by the pendulum appliance (PA) and the distal screw appliance (DS) in Class II patients. Methods: Forty-three patients (19 men, 24 women) with Class II malocclusion were retrospectively selected for the study. Twenty-four patients (mean age, $12.2{\pm}1.5years$) were treated with the PA, and 19 patients (mean age, $11.3{\pm}1.9years$) were treated with the DS. The mean distalization time was 7 months for the PA group and 9 months for the DS group. Lateral cephalograms were obtained at T1, before treatment, and at T2, the end of distalization. A Mann-Whitney U test was used for statistical comparisons of the two groups between T1 and T2. Results: PA and DS were equally effective in distalizing maxillary molars (4.7 mm and 4.2 mm, respectively) between T1 and T2; however, the maxillary first molars showed less distal tipping in the DS group than in the PA group ($3.2^{\circ}$ vs. $9.0^{\circ}$, respectively). Moreover, significant premolar anchorage loss (2.7 mm) and incisor proclination ($5.0^{\circ}$) were noted in the PA group, whereas premolar distal movement (1.9 mm) and no significant changes at the incisor ($0.1^{\circ}$) were observed in the DS group. No significant sagittal or vertical skeletal changes were detected between the two groups during the distalization phase. Conclusions: PA and DS seem to be equally effective in distalizing maxillary molars; however, greater distal molar tipping and premolar anchorage loss can be expected using PA.