• The korean journal of orthodontics
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• v.20 no.2
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• pp.333-354
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• 1990

This study was designed to analyse vertical dysplasia such as open bite or deep bite in persons with skeletal Class III malocclusion. The subjects consisted of 60 control patients, 40 Class III open bite patients and 40 Class III deep bite patients. The mean age was 19.8 years in the control group, 17.8 years in the Class III open bite group and 16.5 years in the Class III deep bite group. The results were as follows: 1. In Class III malocclusion patients, the characteristics of the vertical dysplasia are under the palatal plane. 2. In Class III malocclusion patients, the items showing the characteristics of the vertical dysplasia are mandibular plane angle, lower gonial angle, lower facial height, dental height & inclination of the upper first molar, interincisal angle, maxillary & mandibular occlusal plane angle. 3. In Class III malocclusion patients, LPFH/LAFH ratio shows the highest significance among the facial height ratios. 4. In Class III malocclusion patients, open bite group has a upward cant of maxillary occlusal plane & downward cant of mandibular occlusal plane. And deep bite group has a downward cant of maxillary occlusal plane & upward cant of mandibular occlusal plane. 5. In Class III malocclusion patients, the molar teeth of the open bite group are measially inclined and those of the deep bite group are upright.

• The korean journal of orthodontics
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• v.24 no.4 s.47
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• pp.827-839
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• 1994

This study was conducted to assess the positional changes of hyoid bone following the use of activator in Angles class III malocclusion patients with functional factors. For this study, 40 Angle's class I patients and 40 Angle's class III patients, totally 80 subjects were used. They are all in Hellman's dental age IIIB-IIIC ranges. In lateral cephalogram to compare Angle's class I group and Angle's class III group, and the positional changes of the hyoid bone before and after the use of activator in Angle's class III malocclusion group. The results were obtained as follows; 1. Comparison of Angle's class I group and Angle's class III group. In comparison to Angle's class I group, hyoid bone is more anteriorly and superiorly positioned in Angle's class III group. The hyoid bone showed reverse inclination to the mandibular plane in Angle's class III malocclusion group. 2. Comparison of the hyoid positional change before and after use of Activator in Angle's class III malocclusion group. The hyoid bone is displaced posteriorly and inferiorly in vertical relationship. The hyoid bone also showed counter-clockwise rotation. 3. No statistical difference was found between after Activator use data of Angle's class m malocclusion group and Angle's class I group. It is concluded that the hyoid bone in Angle's class III malocclusion group changed its position, similar to Angle's class I malocclusion group.

• The korean journal of orthodontics
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• v.9 no.1
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• pp.85-98
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• 1979

This investigation was designed to compare the craniofacial and dental morphology of class III malocclusion with that of normal occlusin in children, and to determine the incidence of various class III craniofacial skeletal patterns. The material selected for this study consisted in standard lateral cephalograms of eighty two Korean children, forty one boys and forty one girls, aged 10 through 12 years, having class III malocclusion, and forty two Korean children, twenty boys and twenty two girls, with normal occlusion in the same age. Using the tracings of the standard lateral cephalograms, various angular and linear measurements were recorded, tabulated and statistically analyzed, and then the class III craniofacial skeletal morphology was divided into various patterns by the degree of SNA and SNB, which respectively were below, within or beyond the normal range of those of normal occlusion. The following characteristics of the craniofacial and dental morphology of class III malocclusion were observed. 1. The cranial base length of class III malocclusion was smaller than that of normal occlusion, and the small saddle angle was a characteristic figure of class III malocclucion. 2. Maxillary length of class III malocclusion was smaller than that of normal occlusion, and point A was retropositioned relative to cranial base but not PNS in class III malocclusion. Maxillary base inclination was not significantly different between the two, but occlusal plane to palatal plane was small in class III malocciusion. 3. The mandibular body length shown no difference between the two, but the mandibular body positioned anteriorly relative to cranial base in class III malocclusion. Ramus height, gonial angle, and mandibular effective length were large in class III malocclusion. Mandibular plane angle and joint angle had no difference between the two, and occlusal plane to mandibular plane angle was large in class III malocclusion. 4. Maxillary incisor inclination was not significantly different between class III malocclusion and normal occlusion, but mandibular incisors positioned and inclined lingually and consequently interincisal angle was large in class III malocclusion. 5. Class III malocclusion was divided into six categories of craniofacial skeletal pattern. The most common class III pattern was found to be one in which the maxilla was within the normal range of prognathism while the mandible extended beyond this range. The pattern in which the maxilla was below the normal range of prognathism while the mandible was within this range was approximately one fifth of the class III sample.

• The korean journal of orthodontics
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• v.17 no.1
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• pp.63-72
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• 1987

This is to investigate the difference between craniofacial correlation of Angle's class III malocclusion and that of normal occlusion. For this investigation, 28 adult males and famales, who have class III malocclusion, and 35 adult males and 46 adult famals., who have normal occlusion were selected to measure actual dimension of cranial base and to investigate ratio of various parts of maxillofacial skeleton against cranial base. Class III malocclusion were, also , classified based on SNA and SNB angle in normal range. Results were as follows. 1. In class III malocclusion, actual dimension of cranial base were appeared to be less than normal occlusion in both sex. 2. In class III malocclusion, values were less than normal occlusion in BN/ptm-A in both sex, but had no significance between two. 3. In class III malocclusion, ramal inclination, mandible inclination, BN/Go-Pog, lower genial angle were appeared to be greater. Thus, characteristic mandibular protrusive appearance of class III malocclusion was due to relative ratio and morphologic characteristic of mandibular body dimension against cranial base. 4. In class III malocclusion, upper incisors were labially tilted and lower incisors were lingually tilted compared to normal occlusion. 5. In typing of class III malocclusion, the most common type was found to be one which maxillas were in normal range, while mandibles were in protrusive tendency.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.4
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• pp.599-612
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• 2007

The present study was designed to compare the morphological and structural differences of craniofacial structures among 146 children with Class I and Class III malocclusions. The results below were obtained from the study. 1. Sphenoethmoidal synchondrosis continues to grow later in Class III. 2. Anteroposterior length of the nasomaxillary complex was significantly shorter in Class III, but the height of the nasomaxillary complex was similar. 3. Mandibular length and mandibular body length were longer in Class III, but had no statistical significance. Lower anterior facial height was shorter in Class III, but had no statistical significance. 4. Dentoalveolar height was similar between Class I and Class III. 5. In Class I, anterior cranial base took part in the anteroposterior length of the nasomaxillary complex and the mandible. 6. In Class III, anterior cranial base and middle cranial base had higher correlation with the mandible with aging. These results suggest that there exist a little differences between Class I and Class III malocclusions at age $7{\sim}11$, but growth patterns are mostly similar. Therefore it is necessary to correct Class III malocclusions at an early age before skeletal differences appear.

• Journal of the korean academy of Pediatric Dentistry
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• v.11 no.1
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• pp.41-56
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• 1984

The purpose of this study is to obtain the normal range of mandibular movement for 13 year old boys and girls, and to compare it to the range of mandibular movement of class III patient and normal adult for diagnosis and prognosis of class III malocclusion and TMJ dysfunction. The subjects were 20 normal boys 20 normal girls 22 class III boys and 18 class III girls. The author measured the ranges and shapes of movement of the mandible in the frontal, sagittal and horizontal trajectories using Saphon visitrainer C II (Tokyo Shizaisha Inc.) for the subjects. The results obtained are as follows: 1) The mean for maximum right laterotrusion in the frontal trajectory were 11.96mm in N.B., 11.10mm in N.G., 11.32mm in III. B., 11.24mm in III G. The mean for maximum left laterotrusion were 11.48mm, 11.0mm, 10.91mm, 10.44mm respectively, Area of border movement were 7.16cm in N.B., 6.59cm in N.G., 7.29cm in III. B., 7.50cm in III. G. 2) The mean for maximum protrusion in the sagittal trajectory were 11.7mm in N.B., 11.4mm in N.G.,11.87mm in III B., and 11.02mm in III. G. 3) The mean for maximum protrusion in the horizontal trajectory were 10.20mm in N.B.,10.00 mm in N.G., 9.12mm for III. B. and 9.36mm in III. G. 4) The mean for maximum protrusion of Class III subjects were shorter than those of normal subjects. 5) There was no sexual difference in the range of mandibular movement for 13 year old subjects. N.B; Normal boys N.G.; Normal girls III.B.; Class III boys III. G.; Class III girls.

• The korean journal of orthodontics
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• v.21 no.2 s.34
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• pp.419-432
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• 1991

The purpose of this study is to observe how the Class III intermaxillary elastics act upon the craniofacial structures of mixed dentition with anterior crossbites. The cephalometric headplafes of 16 childrens treated only with Class III elastics (C III elastics group) and 23 childrens treated with Class III elastics and Reverse pull headgear simultaneously (C III elastics + RPHG group) were traced, digitized and statistically analyzed. The results were as follows. 1 . Anterior displacement of maxilla was observed in both groups. 2. Simultaneous Class III elastics and reverse pull headgear group showed the counterclockwise rotation of maxilla, however Class III elastics group manifested no rotational change of maxilla. 3. Simultaneous Class III elastics and reverse pull headgear group showed the downward and backward rotation of mandible, however Class III elastics group manifested no rotational change of mandible. 4. Counterclockwise canting of occlusal plane, labial tipping of upper incisor and lingual tipping of lower incisor and mesial displacement of upper molar to pterygoid root vertical were observed in both groups.

• The korean journal of orthodontics
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• v.48 no.6
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• pp.349-356
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• 2018

Objective: This study was performed to investigate the alveolar bone of lower incisors in skeletal Class III adults of different vertical facial patterns and to compare it with that of Class I adults using cone-beam computed tomography (CBCT) images. Methods: CBCT images of 90 skeletal Class III and 29 Class I patients were evaluated. Class III subjects were divided by mandibular plane angle: high (SN-MP > $38.0^{\circ}$), normal ($30.0^{\circ}$ < SN-MP < $37.0^{\circ}$), and low (SN-MP < $28.0^{\circ}$) groups. Buccolingual alveolar bone thickness was measured using CBCT images of mandibular incisors at alveolar crest and 3, 6, and 9 mm apical levels. Linear mixed model, Bonferroni post-hoc test, and Pearson correlation analysis were used for statistical significance. Results: Buccolingual alveolar bone in Class III high, normal and low angle subjects was not significantly different at alveolar crest and 3 mm apical level while lingual bone was thicker at 6 and 9 mm apical levels than on buccal side. Class III high angle group had thinner alveolar bone at all levels except at buccal alveolar crest and 9 mm apical level on lingual side compared to the Class I group. Class III high angle group showed thinner alveolar bone than the Class III normal or low angle groups in most regions. Mandibular plane angle showed negative correlations with mandibular anterior alveolar bone thickness. Conclusions: Skeletal Class III subjects with high mandibular plane angles showed thinner mandibular alveolar bone in most areas compared to normal or low angle subjects. Mandibular plane angle was negatively correlated with buccolingual alveolar bone thickness.

• The korean journal of orthodontics
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• v.1 no.1
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• pp.33-37
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• 1970

Class III malocclusions are difficult to treat and take more time than any other types. But if such problems are detected at the earliest opportunity, we may gain the best possible correction consistent with the limitations imposed by morphogenetic pattern. The question of whether a patient has false or real Class III malocclusion is not important. Therapy wilt eleminate the malrelationship, in any event. Graber said, 'It has been my experience that many so-called 'pseudo' Class III's are full-blown Class III's later on during the prolific growth period.' The authors have attempted early treatment of a Class III malocclusion of 8-year old girl, who has the familial history of Class III malocclusion.

• The korean journal of orthodontics
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• v.42 no.4
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• pp.190-200
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• 2012

Objective: The displacement of the hyoid bone (HB) is a critical biomechanical component of the swallowing function. The aim of this study was to evaluate the swallowing-induced vertical and horizontal displacements of the HB in subjects with 2 different magnitudes of skeletal Class III malocclusion, by means of real-time, balanced turbo-field-echo (B-TFE) cine-magnetic resonance imaging. Methods: The study population comprised 19 patients with mild skeletal Class III malocclusion, 16 with severe skeletal Class III malocclusion, and 20 with a skeletal Class I relationship. Before the commencement of the study, all subjects underwent cephalometric analysis to identify the nature of skeletal malformations. B-TFE images were obtained for the 4 consecutive stages of deglutition as each patient swallowed 10 mL of water, and the vertical and horizontal displacements of the HB were measured at each stage. Results: At all stages of swallowing, the vertical position of the HB in the severe Class III malocclusion group was significantly lower than those in the mild Class III and Class I malocclusion groups. Similarly, the horizontal displacement of the HB was found to be significantly associated with the severity of malocclusion, i.e., the degree of Class III malocclusion, while the amount of anterior displacement of the HB decreased with an increase in the severity of the Class III deformity. Conclusions: Our findings indicate the existence of a relationship between the magnitude of Class III malocclusion and HB displacement during swallowing.