• The korean journal of orthodontics
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• v.31 no.1 s.84
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• pp.25-38
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• 2001

The purpose of this study was to compare the force, the displacement and the stress distribution on the maxillary first molars altered by the application of various asymmetric head-gear. For this study, the finite element models of unilateral Cl II maxillary dental arch was made. Also, the finite element models of asymmetric face-bow was made. Three types of asymmetric face-bow were made : each of the right side 15mm, 25mm and 35mm shorter than the left side. We compared the forces, the displacement and the distribution of stress that were generated by application of various asymmetric head-gear, The results were as follows. 1. The total forces that both maxillary first molars received were similar in all groups. But the forces that mesially positioned tooth received were increased as the length of the outer-bow shortened, and the forces that normally positioned tooth received were decreased as the length of the outer-bow shortened. 2. In lateral force comparison, the buccal forces that normally positioned tooth received were increased as the length of the outer-bow shortened, and the buccal fortes that mesially positioned tooth received were decreased as the length of the outer-bow shortened. Though the net lateral force moved to the buccal side of normally positioned tooth as the length of the outer-bow shortened, both maxillary first molars received the buccal force. That showed 'Avchiai Expansion Effect' 3. The distal forces, the extrusion forces and the magnitudes of the crown distal tipping that mesially positioned tooth received were increased as the length of the outer-bow shortened, and the forces that normally positioned tooth received were decreased as the length of the outer-bow was shortened. 4. The magnitude of the distal-in rotation that normally positioned tooth received were increased as the length of the outer-bow was shortened. But, mesially positioned tooth show two different results. For the outer-bow 15mm shortened, mesially positioned tooth showed the distal-in rotation, hut for the outer-bow 25mm and 35mn shortened, mesially positioned tooth showed the distal-out rotation. Thus, the turning point exists between 15mm and 25mm. 5. This study of the initial stress distribution of the periodontal ligament at slightly inferior of the furcation area revealed that the compressive stress in the distobuccal root of the normally positioned tooth moved from the palatal side to the distal side and the buccal side successively as the length of the outer-bow shortened. 6. This study of the initial stress distribution of the periodontal ligament at slightly inferior of the furcation area revealed that the magnitudes of stress were altered but the total stress distributions were not altered in the mesiobuccal root and the palatal root of normally positioned tooth, and also three roots of mesially positioned tooth as the length of the outer-bow shortened.

• The korean journal of orthodontics
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• v.30 no.2 s.79
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• pp.159-174
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• 2000

Many treatment approaches of Cl III malocclusion have been introduced and the choice of treatment should be a function of the individual problem, not of the clinician(personal preference, experience and success rate of the operator). Therefore a function of the individual problem should be analysed exactly Much has been written in the orthodontic literature concerning the nature of Cl III malocclusion. It has been reported by many investigators that a Cl III malocclusion occurs in a variety of skeletal and dental configurations by differences of race and age. Lateral cephalometric radiographs of 125 individuals were studied for the presence and distibution of four horizontal components and one vortical component in a manner similar to McNamara. The results were as follows : 1. Cl III malocclusion is not a single clinical entity. It can result from numerous combinations of skeletal and dental components. 2. Maxillary skeletal retrusion was the most common single charateristic of the Cl III sample. 3. Only a small percentage of the cases in this study exhibited maxillary dentoalveolar protrusion. 4. Only a small percentage of the cases in this study exhibited mandibular dentoalveolar retrusion. 5. Mandible was usually well-positioned, but a wide variation was observed. 6. A large percentage of the cases in this study exhibited excessive vertical development. Thus, it appears that in designing the ideal treatment regime, those approaches which might restrict vertical development and promote maxillary horizontal growth could be more appropriate in many cases.

• The korean journal of orthodontics
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• v.20 no.1
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• pp.111-122
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• 1990

To investigate the relationship of skeletal maturity among the normal occlusion group and each malocclusion groups, the author used hand and wrist X-ray of 133 Korean 13 year old boys (normal occlusion 30, Class I malocclusion 35, Class II malocclusion 35 and Class III malocclusion 33) and assessed their skeletal maturity. In this study, fourteen skeletal maturity stages were selected from; Radius, Hamate, Pisiform, Ulnar sesamoid of the metacarpophalangeal joint of the first thumb, proximal phalanges of the first, second and third finger, middle and distal phalanx of the third finger. The difference of skeletal maturity of each malocclusion groups in relative to normal occlusion group and that of each malocclusion groups were analyzed. The findings of this study can be summerized as follows: 1. Average skeletal maturity stage of each groups were MP3cap stage in normal occlusion group, H-2 stage in Class I malocclusion group, midstage between S and H-2 stage in Class II malocclusion group, MP3cap stage in Class III malocclusion group. 2. There was no significant difference in skeletal maturity of Class I malocclusion and Class III malocclusion groups in relative to normal occlusion group. 3. There was significant retardation of skeletal maturity in Class II malocclusion group in relative to normal occlusion group. 4. There was no significant difference in skeletal maturity between Class I and Class II malocclusion groups. 5. There was no significant difference in skeletal maturity between Class I and Class III malocclusion groups. 6. There was significant retardation of skeletal maturity in Class II malocclusion group in relative to Class III malocclusion group.

• Journal of the korean academy of Pediatric Dentistry
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• v.23 no.2
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• pp.537-548
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• 1996

To investigate the relationship between the calcification stages of mandibular canines and the skeletal maturity stage of the hand-wrist in subjects with normal occlusion and Class III malocclusion, hand-wrist radiographs and panoramic radiographs were taken from subjects of normal occlusions(94 males, 88 females) and Class III malocclusions(75 males, 76 females) who had no systemic diseases and no history of orthodontic or prosthodontic treatment. Fishman's method for the skeletal maturity stages of the hand-wrist and Demirijian's method for the calcification stages of mandibular canines were used and analyzed. The results were as follows : 1. In subjects with normal occlusion and Class III malocclusion, skeletal maturity of the hand-wrist and calcification of mandibular canines at various ages occured earlier in females than in males(p<0.05). 2. Comparing the skeletal maturity stages of the hand-wrist and the calcification stages of mandibular canines between subjects with normal occlusion and Class III malocclusion, there were no significant differences between the groups. 3. The correlation coefficient between the calcification stages of mandibular canines and the skeletal maturity stages of the hand-wrist. in subjects with normal occlusion and Class III malocclusion showed a high association(p<0.01). 4. In stage 4 of the skeletal maturity of the hand-wrist, the frequency distribution of calcification G stage among the various calcification stages was highest both in normal occlusion and in subjects with Class III malocclusion. However, there was no significant difference in the frequency distribution of calcification stages between the groups.

• The korean journal of orthodontics
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• v.18 no.1 s.25
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• pp.89-104
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• 1988

This study was performed to investigate the relationships between the EMG activity of the masticatory muscles in Angle's Class II div. 1 malocclusion and normal occlusion. This study was ranged from age 12 to 14 year-old for 30 male subjects: 15 subjects were Angle's Class II div. 1 malocclusion, and 15 subjects were normal occlusion with acceptable profile. Their cephalometric measurement were analyzed, and the EMG recordings from the anterior temporal, posterior temporal, masseter, and orbicularis oris muscles were analyzed during rest position, mastication of peanuts, and swallowing. All data was recorded and statistically processed with the VAX-11/780 computer system. The results were as follows: 1. The activity of muscles at rest was highest in the posterior temporal muscle with normal occlusion, as well as in those with Class II div. 1 malocclusion, and the posterior temporal muscle activity of Class II div. 1 malocclusion was higher than that of normal occlusion. 2. During mastication, all muscle activities of Class II div. 1 malocclusion were recorded lower than those of normal occlusion, and the activity of the anterior temporal muscle was higher than that of the posterior temporal muscle in both types of occlusion. 3. As for the activity in orbicularis oris muscle, it was greater in opening phase than in closing phase during chewing cycle with both types of occlusion. 4. During swallowing, the activities of the anterior temporal, masseter, and orbicularis oris muscles of Class II div. 1 malocclusion were recorded lower than those of normal occlusion.

• The korean journal of orthodontics
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• v.32 no.1 s.90
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• pp.19-31
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• 2002

To investigate the association between the hypertrophy of adenoid and jaw morphology during growth, this paper was based on children patients with experimental adenoids (male-15 subjects at each bone age group, female-15 subjects at each bone group) and comparing them to data taken from a control group (male-15 subjects at each bone age group, female-15 subjects at each bone group) with normal respiratory function. The comparisons between the groups were done at each growth stage using cervical vertebrae maturation index(CVMI) of Hassel. The obtained results were as follows : 1. The differences in craniofacial morphology between experimental group and control group were appeared from CVMI 3 and CVMI 4 (aroud adolescent period) in males, and from CVMI 1 in females. 2. The mandibular position of experimental group was more inferior than control group. The difference appeared at adolescent period(male : at CVMI 4, female : at CVMI 5). 3. Experimental group had greater anterior facial height than control group. This difference seemed a relation with lower anterior facial height. The difference appears at CVMI 3(11.94 ${\pm}$ 1.38 years old, at adolescent period) in male and at CVMI 1 in female. 4. The adenoid size of control male group was increased until CVMI 2(10.58 ${\pm}$ 1.07 years old, just before adolescent growth peak) and then decreased, but in female the adenoid size was decreased from CVMI 1(6.92 ${\pm}$ 0.53 years old).

• The korean journal of orthodontics
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• v.36 no.1 s.114
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• pp.14-29
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• 2006

Developments in computer technology have made possible the 3-dimensional (3-D) evaluation of hard and soft tissues in orthodontic diagnosis, treatment planning and post-treatment results. In this study, Korean adults with normal occlusion (male 30, female 30) were scanned by a 3-D laser scanner, then 3-D facial images formed by the Rapidform 2004 program (Inus Technology Inc., Seoul, Korea.). Reference planes in the facial soft tissue 3-D images were established and a 3-D coordinate system (X axis-left/right, Y axis-superior/inferior, Z axis-anterior/posterior) was established by using the soft tissue nasion as the zero point. Twenty-nine measurement points were established on the 3-D image and 43 linear measurements, 8 angular measurements, 29 linear distance ratios were obtained. The results are as follows; there were significant differences between males and females in the nasofrontal angle $(male:\;142^{\circ},\;female:\;147^{\circ})$ and transverse nasal prominence $(male:\;112^{\circ},\;female:\;116^{\circ})$ (p<0.05). The transverse upper lip prominence was $107^{\circ}$ in males, $106^{\circ}$ in females and the transverse mandibular prominence was $76^{\circ}$ in both males and females. Li-Me' was 0.4 times the length of Go-Me'(mandibular body length) and the mouth height was also 0.4 times the width of the mouth width. The linear distance ratio from the coronal reference plane of FT, Zy, Pn, ULPm, Li, Me' was -1/-1/1/0.5/0.5/-0.6 respectively. The 3-D facial model of Korean adults with normal occlusion were be constructed using coordinate values and linear measurement values. These data may be used as a reference in 3-D diagnosis and treatment planning for malocclusion and dentofacial deformity patients and applied for 3-D analysis of facial soft tissue changes before and after orthodontic treatment and orthognathic surgery.

• The korean journal of orthodontics
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• v.37 no.2 s.121
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• pp.114-124
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• 2007

Objective: The purpose of this study was to examine how the mesio-distal angulation and the length of each tooth changes on panoramic radiograph at different bucco-lingual inclinations. Methods: After constructing an acrylic model based on the mean arch of 30 adults with normal occlusion, the wire was placed in the center of the teeth on the acrylic model. First, the wire was implanted in normal angulation and inclination and a panoramic radiograph taken. After changing the inclination from $I-5^{\circ}\;to\;I+15^{\circ}\;by\;5^{\circ}$, a panoramic radiograph was taken again and the mesio-distal angle and wire length on the panoramic radiograph were assessed. Results: When the wire was implanted at the normal angulation and inclination, the length measured in the panoramic radiograph was magnified $111{\sim}117%$ from the original length in the anterior region and $121{\sim}125%$ in the posterior region. Only the central and lateral incisors showed significant length differences when the inclination was changed from $l-15^{\circ}\;to\;I+15^{\circ}$ at fixed angulation. When the inclination was changed from $l-15^{\circ}\;to\;I+15^{\circ}$, the angulation of most teeth on panoramic radiograph appeared to be more disto-angulated than in reality, and the lateral incisor and canine showed the largest difference. Only $l-15^{\circ}\;to\;I+15^{\circ}$ groups of premolars and $I+15^{\circ}$ group of molars showed more mesio-angulation than in reality. As the labio(bucco)lingual inclination of all teeth were decreased, tooth angulation in the panoramic radiograph appeared to be more disto-angulated. Conclusion: The labio-liugual inclination of teeth should be considered because it affects panoramic image of teeth, such as length of incisors and angulation of other teeth.

• The korean journal of orthodontics
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• v.25 no.4
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• pp.447-451
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• 1995

The purpose of this study was to investigate the effects of cleft on mesiodistal dimensions of permanent teeth in unilateral cleft lip and palate patients. Mesiodistal dimensions of permanent teeth were measured to the nearest 0.01mm on plaster models of 50 subjects with unilateral complete cleft lip and palate, 10 siblings and 50 Controls. The results were as follows : 1. Tooth size discrepancy in the cleft group was significant in all regions except maxillary cuspid, mandibular cuspid and mandibular first premolar. 2. Some of the mesiodistal dimensions of the teeth on the cleft side were significantly smaller than those of their antimeres on the non-cleft side in the cleft group. 3. A comparison of mesiodistal dimensions of the teeth for the right and left sides of the control group showed no statisically significant differences excepts maxillary lateral incisor. 4. Asymmetries of mesiodistal dimensions of the teeth in the sibling group was not found except maxillary first molar.

• The korean journal of orthodontics
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• v.22 no.3 s.38
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• pp.675-690
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• 1992

The purpose of this study was to obtain the lingual morphology (size, angulation, contour, eminence) of adults with normal occlusion in order to provide the basic data for lingual bracket and lingual arch form in Korean. The subjects (Male: 50, Female: 50) were selected who have normal occlusion and dental casts were prepared. Tooth size, angulation, arch width, horizontal contour, lingual eminence were measured for all 28 teeth both upper and lower arch. The results were as follows: 1. Measuring items of all individual teeth for adults with normal occlusion were obtained. 2. In comparison tests, there was a statistically difference between intermolar widths $(\underline{6}\;to\;\underline{6})$ before occlusal reduction and intermolar width $(\underline{6}\;to\;\underline{6},\underline{7}\;to\;\underline{7})$ after occlusal reduction only all the other measuring items showed no statistically differences. 3. There was small variation in horizontal contour of lingual surface on lower incisors and upper and lower bicuspids. The other teeth showed somewhat greater variations. 4. There was offset between canine and bicuspid in upper arch while there was no prominent offset in lower arch.