• The korean journal of orthodontics
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• v.52 no.1
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• pp.66-74
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• 2022

Objective: To investigate demographic and skeletodental characteristics of one-jaw (1J-OGS) and two-jaw orthognathic surgery (2J-OGS) in patients with skeletal Class III malocclusion. Methods: 750 skeletal Class III patients who underwent OGS at 10 university hospitals in Korea between 2015 and 2019 were investigated; after dividing them into the 1J-OGS (n = 186) and 2J-OGS groups (n = 564), demographic and skeletodental characteristics were statistically analyzed. Results: 2J-OGS was more frequently performed than 1J-OGS (75.2 vs. 24.8%), despite regional differences (capital area vs. provinces, 86.6 vs. 30.7%, p < 0.001). Males outnumbered females, and their mean operation age was older in both groups. Regarding dental patterns, the most frequent maxillary arch length discrepancy (ALD) was crowding in the 1J-OGS group (52.7%, p < 0.001) and spacing in the 2J-OGS group (40.4%, p < 0.001). However, the distribution of skeletal pattern was not significantly different between the two groups (all p > 0.05). The most prevalent skeletal patterns in both groups were hyper-divergent pattern (50.0 and 54.4%, respectively) and left-side chin point deviation (both 49.5%). Maxillary spacing (odds ratio [OR], 3.645; p < 0.001) increased the probability of 2J-OGS, while maxillary crowding (OR, 0.672; p < 0.05) and normo-divergent pattern (OR, 0.615; p < 0.05) decreased the probability of 2J-OGS. Conclusions: In both groups, males outnumbered females, and their mean operation age was older. The most frequent ALD was crowding in the 1J-OGS group, and spacing in the 2J-OGS group, while skeletal characteristics were not significantly different between the two groups.

• Journal of the korean academy of Pediatric Dentistry
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• v.41 no.4
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• pp.298-305
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• 2014

The purpose of this study is to evaluate the effects of facemask therapy in patients with Class III malocclusion with two types of bonded expanders covering different numbers of anchored teeth and to compare the anchorage value of two types of bonded expander. Eighteen subjects with Class III malocclusion in early mixed dentition were included in this study, and subjects were divided into two groups based on the number of teeth covered by bonded expander: group 1 (splinting four teeth on each side, 9 subjects) and group 2 (splinting three teeth on each side, 9 subjects). Lateral cephalograms were obtained and assessed before (T1) and after (T2) the treatment. The facemask therapy showed skeletal effects including anterior movement of maxilla and backward rotation of mandible in both groups, with no significant differences between groups. Mesial movement of maxillary molars which indicates anchorage loss of the bonded expander was found in both groups, but significantly larger mesial movement was found in group 2 than in group 1. In conclusion, the value of anchorage was different according to the number of teeth covered by bonded expander as an intraoral anchorage of facemask, but there were no significant differences in skeletal effects.

• Journal of the korean academy of Pediatric Dentistry
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• v.26 no.3
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• pp.564-571
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• 1999

The importance of the hyoid bone lies in its unique anatomic relationships. It has no bony articulations but provides attachment for muscles, ligaments, and fascia of the pharynx, mandible, and cranium. Various studies have documented a variability of hyoid bone position in relation to changed mandibular position or head posture. The aim of this study is to investigate the hyoid bone position and inclination on cephalometric radiographs of three groups of patients exhibiting Class I, II, and III malocclusions. The conclusions obtained from this study can be summarized as follows ; 1. Class III malocclusion patients show a more anterior position of the hyoid bone and also less steep inclination of the hyoid bone. 2. The anteroposterior position of the hyoid bone relative to the cervical vertebra and mandible was very constant. 3. The hyoid bone represented the anterior bony boundary of the pharynx at a lower level than PNS.

• The korean journal of orthodontics
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• v.37 no.1 s.120
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• pp.44-55
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• 2007

Objective: Previous studies have reported that morphological features of the first cervical vertebra (atlas) have been associated with mandibular growth direction. The purpose of this study was to show the possible positional and morphological changes of the Atlas from activator treatment in Class II malocclusion patients. Methods: Lateral cephalometric radiograph tracings were made at initial, middle and final stages of treatment. Angular and linear measurements of skeletal and morphological features were measured on the anatomical landmarks and reference planes. Results: The skeletal effects of activator treatment on Class II malocclusion patients were evident on ramal height, body length, effective body length, ANB, and overjet. Clockwise rotation of the long axis of the Atlas was found in Group 1, but there was no inclination change of the Atlas in groups 2 and 3. There was no significant correlation between anterior and posterior positions of the atlas or morphological change in all groups. - except for posterior movements of the Atlas found in group 1. Conclusion: Clockwise rotation of the atlas axis resulted from activator treatment in Cl II malocclusion patients. Change in atlas axis can be thought of as an indicator for success of activator treatment.

• The korean journal of orthodontics
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• v.27 no.1
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• pp.45-54
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• 1997

The purpose of this study was to evaluate the indications of bionator in Class II division 1 malocclusion, The 48 subjects were classified into good result group(group1) and poor result group(group2) in reference to posttreatment molar relation, posttreatment overbite and overjet, posttreatment profile, and relapse. Pretreatment lateral cephalograms were calculated and evaluated by t-test stepwise discriminant analysis. The results were as follows ; 1. In jaw bone relationship, ANB, facial convexity angle, AB to facial plane angle were significantly different between two treatment groups. In denture pattern, L1 to facial plane, L1 to A-Pog, FMIA, and U1 to facial plane were significantly different and m soft tissue profile, protuberance of lower lip and upper lip were significantly different between tw o treatment groups. 2. The results in according to discriminant analysis stated that L1 to facial plane, ANB, FMIA and protuberance of lower lip help prediction of treatment result of bionator. 3. 3 major influential variables were obtained by stepwise discriminant analysis - L1 to facial plane, articular angle and ANB difference. And Fisher discriminant function was made by these three major variables.

• The korean journal of orthodontics
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• v.27 no.1
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• pp.21-33
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• 1997

The purpose of this study was to investigate the factors affecting the postsurgical mandibular stability for both one- and two jaw surgery. 18 for one-jaw surgerys and 24 for two-jaw surgerys among skeletal class III malocclusion patients who experienced orthodontic treatment and orthognathic surgery at Pusan National University Hospital were selected. Lateral cephalograms taken at the first visit, after presurgical orthodontic treatment, immediately after surgery and follow-up over 6 months, were traced. Based ANOVA, multiple linear regression analysis was completed for one-jaw surgery with postsurgical stability as the criterion and the magnitude of mandibular setback, the change of mandibular incisor height during surgery, the changes of mandibular plane angle and mandibular incisor angle during presurgical orthodontic treatment as affecting factors. Same analysis was completed for two-jaw surgery with postsurgical stability as the criterion and the magnitude of mandibular setback as affecting factor. The results were as follows : 1. In the one-jaw surgery cases, the magnitude of mandibular setback, the change of mandibular incisor height during surgery, the changes of mandibular plane angle and mandibular incisor angle during presurgical orthodontic treatment explained the variability in postsurgical stability with a significant $R^2$ value of 0.84. 2. In the two-jaw surgery cases, the magnitude of mandibular setback explained the variability in postsurgical stability with a significant $R^2$ value of 0,28.

• The Journal of the Korean dental association
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• v.39 no.10 s.389
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• pp.854-865
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• 2001

• The korean journal of orthodontics
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• v.34 no.6 s.107
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• pp.497-505
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• 2004

The purpose of this study was to evaluate the post-retention stability of the lower incisor axis in Class II division 2 malocclusions. The dental casts and lateral cephalograms from before (T1) and after (T2) orthodontic treatment and long-term post-retention (T3) in 62 Class II division 2 malocclusion cases were included in this study. After several linear and angular measurements at each time were taken, the significance in the amount of change of the lower incisor axis for each gender and extraction versus non-extraction was evaluated. The results showed that the lower incisors that inclined labially during treatment were unstable and relapsed to the original lingual position in Class II division 2 malocclusions (p<0.001). There was no significant difference between extraction and non-extraction groups for the amount of lingual relapse of the lower incisors (p>0.05). There was no significant difference between male and female groups for the axial change of the lower incisors (p>0.05). As a result of multiple regression analysis, the cephalometric measurement best predicting the lower incisor position to the A-Pog line post-retention was pre-treatment L1-Apog(mm) and pre-treatment SNGoMe$(^{\circ})$. Because of the instability of labially inclined lower incisors after orthodontic treatment, the treatment goal should be the pre-treatment incisor axial position.

• Journal of Korean Dental Science
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• v.7 no.1
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• pp.6-15
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• 2014

Purpose: The purpose of this retrospective study is to investigate the degree of coincidence between the peer assessment rating (PAR) index and American Board of Orthodontics objective grading system (ABO-OGS) in the assessment of orthodontic treatment outcomes of Class I malocclusion cases. Materials and Methods: The sample consisted of 26 Class I patients. The PAR index was used for evaluation of pre-(T0) and posttreatment (T1) casts, and the ABO-OGS for assessment of T1 casts. If there was a reduction in PAR scores from T0 to T1 of more than 30%, the label 'PAR+' was given to the case, and if not, it was labeled 'PAR-'. If the ABO-OGS was less than 27, the label 'OGS+' was given to the case and if not, it was labeled 'OGS-'. 'A PAR-only qualified group' (PAR+), 'ABO-OGS-only qualified group' (OGS+), 'both indices qualified group' (PAR+/OGS+), and 'both indices disqualified group' (PAR-/OGS-) were compared with a Wilcoxon rank-sum test, sensitivity/specifi city test and Spearman's correlation test. Result: PAR scores for T0, T1, and percentage reduction were 21.1, 6.4, and 65.9%, respectively, and 35.4 for ABOOGS. The distribution of the 'PAR+/OGS+', 'PAR+', and 'PAR-/OGS-' group was 19.3%, 76.9%, and 3.8%, respectively. The T0-PAR, T1-PAR and PAR point reductions for the 'PAR+' group were significantly higher than those of 'PAR+/OGS+' groups (23.1 vs. 15.6; 6.7 vs. 4.6; and 16.5 vs. 11.0; all P<0.05). However, the PAR-percentage reduction and treatment duration between the two groups were not statistically different (70.0% vs. 67.0%, P=0.4325; 24.1 months vs. 25.0 months, P=0.4057). The T1-ABO-OGS score for 'PAR+' group was significantly higher than that of the 'PAR+/OGS+' groups (38.2 vs. 24.0, P<0.001). Conclusion: Since the fraction of the 'PAR+/OGS+' group was less than 20% and there was no significant correlation between PAR-percentage reduction and T1-ABO-OGS, development of a new index system for the accurate evaluation of treatment outcome is needed.

• The korean journal of orthodontics
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• v.30 no.6 s.83
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• pp.687-698
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• 2000

The purpose of this study was to evaluate the changes of skeletodental patterns during Class II treatment and its retention period. Forty two patients of Class II malocclusion, which was treated with nonextraction or first premolar-extraction were selected and their lateral cephalograms were examined in this study. Various skeletodental changes in lateral cephalograms of pre-treatment, post-treatment and retention were measured by superimposition in reference to the cranial base for jaws, the palatal plane for maxillary teeth, and mandibular plane for mandibular teeth. The data were analyzed by paired t-test. In this study, occlusal plane showed the significant anterior downward steepening after active treatment, and remained during retention period. In the nonextraction group, maxillary incisors were retracted and extruded during treatment. Maxillary molars were extended, and mandibular molar were uprighted, with no mesial movement. In the extraction group, both maxillary and mandibular incisors were retracted and extruded. Maxillary molars were extruded and moved mesially, and mandibular molars were extruded and moved mesially with no mesial tilting. During retention period in both groups, there were tendencies of labial tipping of maxillary incisor, and mesial tipping of maxillary and mandibular molar. But the changes were not significant and most of teeth showed no change in vortical and horizontal direction.