• The korean journal of orthodontics
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• v.34 no.2 s.103
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• pp.109-119
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• 2004

This study aimed at investigating the skeletal, dentoalveolar, and soft tissue changes of Class III malocclusion cases treated by second molar extraction. The lateral cephalograms of 15 subjects with moderate Class III malocclusion by average ANB $-1.4^{\circ}\;and\;IMPA\;85^{\circ}$ were traced and the computerized superimposition of average craniofacial change was made. The data was gathered and statistically analyzed. The results were as follows: 1 Lower anterior facial height/anterior facial height increased by 0.6%(P<0.01), mandibular plane increased by $1.5^{\circ}$(P<0.05). 2. There was a slightly downward & backward rotation of the mandible. 3. Lower first molar tipped distally by 4.nm(P<0.001), lower anterior teeth lingually tipped by $3.2^{\circ}$(P<0.05). 4. Retracted lower lip improved facial profile. This study may suggest that second molar extraction could be effective for a moderate Class III malocclusion to make distalization of the lower first molar easier and avoid severe lingual tipping of the lower incisor, if the lower third molar has a normal shape, good direction of eruption and adequate time for lower second molar extraction

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.1
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• pp.108-113
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• 2004

This study was to evaluate and compare differences of the cervical vertebral skeletal maturity of normal occlusion and skeletal Class III malocclusion. Normal occlusion (172 girls) and skeletal Class III malocclusion(191 girls) were classified according to diagnosis stone model and lateral cephalogram of Korean girls aging from 8 to 12 years. The concavity of inferior border, vertico-horizontal ratio of cervical vertebrae were observed and measured according to age. Differences of the cervical vertebral skeletal maturity were evaluated. The results were as follows : 1. The concavity of inferior border of the 2nd to 6th vertebrae of normal occlusion and skeletal Class III had uniformly increased with age. 2. The vertico-horizontal ratio of the 3rd to 6th vertebrae of girls with normal occlusion and skeletal Class III had uniformly increased with age. 3. There was no significant difference in cervical vertebral skeletal maturity between normal occlusion and skeletal Class III malocclusion in the concavity of inferior border of the 2nd to 6th vertebrae and in the vertico-horizontal ratio of the 3rd to 6th vertebrae. The results in the study indicate that there is no significant difference of cervical vertebral skeletal maturity between girls with normal occlusion and skeletal Class III malocclusion.

• The korean journal of orthodontics
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• v.29 no.3 s.74
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• pp.327-337
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• 1999

Patients with skeletal class III can be succesfully treated by either orthognathic surgery or orthodontic treatment owing to unavoidable circumstances. Systers were treated , elder syster by orthognathic surgery and younger one by compromised treatment. For the ideal treatment goal, orthognathic surgery will be inevitable in skeletal problem case, but by the patient's private situations orthodontist cannot help doing compromised treatment. It could be another option if correct biomechanical approach is used.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.2
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• pp.235-242
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• 2008

The purpose of this study was to investigate the relationship of the skeletal maturity of hand-wrist and the development of mandibular third molar in subjects with class I and class III malocclusion. The subjects used in this study were 304 children(149 boys, 155 girls) with class I malocclusions and 308 children( 153 boys, 155 girls) with class III malocclusions, ranged from 8 to 15 years of age. Hand-wrist radiographs and panoramic radiographs were used to evaluate the stage of skeletal maturity and teeth development. Fishman's method for the skeletal maturity stages of the hand-wrist and new six-developmental-stage method for the calcification stages of mandibular third molars were analyzed. The results were as follows : 1. In subjects with class I and class III malocclusion, skeletal maturity of the hand-wrist occured earlier in females than in males(p<0.05), while the calcification stages of mandibular third molars were no significant gender differences. 2. There were no significant differences between the groups, when comparing the skeletal maturity stages of the hand-wrist and the calcification stages of mandibular third molars between subjects with the class I and the class III malocclusion. 3. The correlation coefficients between the calcification stages of mandibular third molars and the skeletal maturity stages of the hand-wrist in subjects with class I and class III malocclusion showed a high interrelationship(p<0.01). 4. The correlation coefficients between the calcification stages of mandibular third molars and chronological age in subjects with class I and class III malocclusion showed a high interrelationship (p<0.01). As a result, there were no significant differences between class I and class III malocclusion group for skeletal maturity of the hand-wrist and third molar development.

• The korean journal of orthodontics
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• v.33 no.1 s.96
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• pp.41-49
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• 2003

This study examined the relations between degree of posterior dental compensation and skeletal discrepancy in Class III malocclusion. The pretreatment lateral cephalogras and dental casts of 87 skeletal Class III adults were selected to provide a random sampling of skeletal Class III malocclusion. Skeletal discrepancy was described with ANB angle, Wits appraisal, SN-Mn plane angle, FMA and ratios of basal arch width. Degree of posterior dental compensation was described with maxillary intermolar angle, mandibular interolar angle and sum of intermoloar angle. The relationships between skeletal discrepancy and degree of posterior dental compensation were analyzed with simple correlation analysis, stepwise multiple regression analysis. The results were as follows 1. A strong association was found between the variation in the anteroposterior measure, ANB angle and the variation of posterior dental compensation measures, sum of intermolar angle and mandibular intermolar angle in skeletal Class III malocclusion. 2. There was no statistically significant relationship between the variation in the vertical measures and the variation of posterior dental compensation measures in skeletal Class III malocclusion. 3. There was no statistically significant relationship between the variation in the anteroposterior and vortical measures and degree of basal arch width discrepancy.

• The korean journal of orthodontics
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• v.25 no.4
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• pp.453-463
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• 1995

Most commonly used axis for central incisors in lateral cephalometric radiographs is the line connecting root apex and incisor edge. However, crown axis and root axis do not always coincide in cases of malocclusion patients. The angle created by these axis are called the collum angle, which should be considered in orthodontic diagnosis and treatment. In this study, 31 Class I malocclusion, 30 Class II division 1 malocclusion, 31 Class II division 2 malocclusion, and 31 Class m malocclusion patients were selected and their collum angles were measured. Correlation between these angles and malocclusions was investigated, and the correlation analysis with other parameters in cephalometrics was done. The results were as follows ; 1. The mean collum angles according to the types of malocclusions are ; $3.11^{\circ}{\pm}3.54^{\circ}$ for Class I, $1.23^{\circ}{\pm}2.41^{\circ}$ for Class II division 1, $3.77^{\circ}{\pm}4.39^{\circ}$ for Class II division 2, and $3.90^{\circ}{\pm}4.08^{\circ}$ for Class III malocclusion. 2. Statistically significant differences in collum angles were noted between Class II division 1 group and Class II division 2 and Class III group. 3. Significant correlations were found between collum angles and other parameters used in cephalometrics, namely IMPA for Class I, Wits for Class II division 1, Overbite for Class II division 2 and for ClassIII.

• The korean journal of orthodontics
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• v.32 no.2 s.91
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• pp.117-127
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• 2002

The purpose of this study was to compare the arch width of the hyperdivergent group with that of the neutral group in Class III malocclusion based on the vertical patterns and to compare the arch width of Class III neutral group With that of normal occlusion group based on sagittal patterns. The subjects consisted of 118 pairs of studty casts, divided into three groups , 37 Class III hyperdivergent group(18 males and 19 females, SN-Mn plane angle>39.5$^{\circ}$), 40 Class III neutral group(20 males and 20 females, SN-Mn plane angle : 32 ${\pm}$ 2.5$^{\circ}$) and 41 Class I normal occlusion group(20 males and 21 females). The intercanine, interpremolar, and intermolar width of the maxillary and mandibular study casts were measured, then the ratios of dental width to basal width and mandibular width to maxillary width were obtained. Basal arch width and dental arch width were measured to obtain the pure basal arch relation in transverse plane as ruled out the transverse dental compensation. The results were as follows 1. There were no significant differences in any ratios between Class III hyperdivergent group and Class III neutral group as different vertical pattern. 2. As the ratios of dental arch width to basal arch width between normal occlusion group and Class III neutral group were compared, the maxillary teeth flared buccally to the basal bone, and the mandibular teeth tilted lingually to the basal bone in Class III neutral group. 3. The ratios of mandibular arch width to maxillary arch width in basal arch level were significantly different in all regions. Maxillary basal arch width of Class III neutral group was narrower than that of normal occlusion group. 4. The ratios of mandibular arch width to maxillary arch width in teeth level were not significantly different between normal occlusion group and Class III neutral group. In spite of discrepancies of maxillary and mandibular basal arch width, the dental arch width of Class III malocclusion group compensated very well. At the presurgical orthodontic treatment in clinic, it would not be desirable to decompensate for compensated dental arch width too much, for obtaining an appropriate arch compatibility and good results for orthognathic surgery.

• The korean journal of orthodontics
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• v.38 no.5
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• pp.358-370
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• 2008

Objective: The purpose of this study was to investigate the horizontal skeletal pattern and dental arch differences between Class III malocclusion patients and normal occlusion patients. Methods: Twenty skeletal Class III malocclusion patients and ten normal occlusion patients were selected and 3D facial CT were taken to analyze the horizontal skeletal differences between the two groups. Results: In the horizontal comparison of the maxilla, skeletal width and perimeter were significantly smaller in skeletal Class III patients on ANS and A point reference planes. The difference between maxillary width of ANS and A point reference planes showed that there was greater constriction of the first and second premolar in skeletal Class III patients. In the horizontal comparison of the mandible, the widths of the canine and premolar area were significantly larger in skeletal Class III patients on B point reference plane. The differences between width of the upper and lower jaws (comparison of A and B reference planes) were significantly large in the canine and premolar area. Conclusions: From this study, the characteristics of Class III malocclusion patients were shown through horizontal constriction of the maxilla. But to make clear further detailed characteristics of Class III malocclusion patients, additional studies are necessary.

• The korean journal of orthodontics
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• v.28 no.5 s.70
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• pp.751-761
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• 1998

The purpose of this study was to find the characteristics of lateral crphalogram of skeletal class III malocclusion patients to whom orthognathic surgery was essential. For this study 37 patients with skeletal class III and going to treat or be treated orthognathic surgery(age 7-17) were selected to experimental group and 56 people with normal occlusion (age 8-13) were selected to normal group and the two groups were evaluated and statistically analyzed and the results were as follows 1. In comparison of experimental group and normal group in prepubertal group, there were significant differences in ANS-U1/Me-L1, Mx. Length/Mn. Length, S-N/Go-Me, Wits, ANB, SN-Pog, IMPA, Facial Convexity, APDI (p<0.05) 2. In comparison of experimental group and normal group in pubertal group, there were significant differences in ANS-U1/Me-L1, S-Go/N-Me, Mx.Length/Mn.Length, S-N/Go-Me, Wits, Saddle Angle, SNB, ANB, SN-Pog, IMPA, Interincisal Angle, Facial Convexity, APDI (p<0.05) 3. Among items showing characteristics of skeletal class III malocclusion, there were no significant differences between prepubertal group and pubertal group in other items except Mx. Length/Mn. Length,APDI (p<0.05) 4. The significant correlationship was the highest between Saddle Angle and SNB, SN-Pog and SNB, ANB and Facial Convexity in experimental group

• The korean journal of orthodontics
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• v.34 no.5 s.106
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• pp.394-407
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• 2004

The Purpose of this study was to evaluate the effect of the lower third molar on treatment time and distal en masse movement of the lower dentition in Giass III malocclusions. Thirty subjects (9 males and 27 females) were selected, all of whom were diagnosed as Glass III malocclusion and treated by fixed appliances without premolar and/or molar extraction. They were divided into three groups Group 1 consisted of 12 subjects. whose lower third molars were not extracted during the whole orthodontic treatment. Group 2 consisted of 8 subjects. whose lower third molars were extracted after WEAW application and before removal of the orthodontic appliances. Group 3 consisted of 10 subjects whose lower third molars were extracted before MEAW application. For each subject. overall treatment time and duration of MEAW application were determined. In addition. pre-treatment and post-treatment lateral cephalometric radiographs were analyzed. All data were Processed statistically with ANOVA, and the conclusions were as follows: There was no significant difference among the groups in overall treatment time However, duration of MEAW application was longer in Group 2 than in Group 1 or Group 3. The overjet that was established after orthodontic treatment was largest in Group 3, in which the lower third molars were extracted befor MEAW application. After orthodontic treatment, IMPA decreased in Group 3. but increased in Group 1 and Group 2. There was no significant difference among the three groups in the translation of lower second molars However the tipping movement of lower second molars was significantly different, highest in Group 2 and lowest in Group 1 Therefore. it is thought to be better for the orthodontic treatment of Class III malocclusions to extract the lower third molars before MEAW application. In Group 2, the mandibular plane angle was decreased as a result of forward rotation of the mandible This skeletal change was thought to bring about the difficulty of treatment.