• The korean journal of orthodontics
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• v.27 no.3 s.62
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• pp.391-399
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• 1997

Rapid palatal expansion(RPE) is a method of inducing the new bone formation in the palate by separation of the midpalatal suture, which can be done conveniently by placing heavy force across the maxillary dental arch. This experiment was undertaken to examine the histologic changes after RPE and during retention period. Four young adult dogs(a control dog, three experimental dogs) aged 4 to 6 months old were used for this experiment. Expansion screw($Hyrax^{\circledR}$, Dentarum Inc.) was delevered to the palate and fumed 180 degrees every morning and evening for 8 days, giving a total expansion of 7.2mm. A control dog was sacrified at the starting point of this study without any treatment and three experimental dogs were sacrified after RPE, 14-day retention, and 28-day retention in each. Thereafter, those samples were observed with hematoxylin-eosin(H-E) stain, ground section(Villanueva stain), alkaline phosphatase(ALP) stain, tartrate-resistant acid phosphatase(TRA) stain. The results were as followings: 1. After RPE, collagen fiber bundles were stretched along the midpalatal suture and few osteoblasts were flattened-inactive state and also, a little osteoid tissues was observed. Few multinucleated osteoclasts which had TRAP-positive activity in their cytoplasm were seen in horizontal section, whereas a few osteoclasts were seen in frontal section, especially in the nasal floor side of palatal bone. 2. After 14-day retention, collagen fiber bundles were stretched along the midpalatal suture and few osteoblasts which had ALP-positive activity in their cytoplasm were seen. Few multinucleated osteoclasts which had TRAP-positive activity in their cytoplasm were seen in horizontal section, whereas a few osteoclasts were seen in frontal section, especially in the nasal floor side of palatal bone. 3. After 28-day retention, collagen fiber bundles were arranged like those of control dog and osteoblasts which showed a lot of immature bone formation were cuboidal shape and exhibited ALP-positive activity in their cytoplasm. Few multinucleated osteoclasts which had TRAP-positive activity in their cytoplasm were seen in horizontal section, whereas a few osteoclasts were seen in frontal section, especially in the nasal floor side of palatal bone. According to the above results, the new bone formation after rapid palatal expansion was examined after 14-day retention and significantly increased after 28-day retention.

• The korean journal of orthodontics
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• v.27 no.3 s.62
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• pp.359-372
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• 1997

This study was conducted to discern differences of craniofacial, dentoalveolar structure and model measurements between sex and between class n openbite group and non-openbite group. The sample consisted of 49 adult patients with class Il malocclusion. 24 linear measurements, 22 angular measurements and 12 ratios were selected in lateral cephalometry. Also, arch width, length, anterior crowding, average molar relation were measured or calculated in diagnostic model. The data were evaluated by t-test and multiple discriminant analysis. The results were as follows, 1. Most linear measurements, with the exception of MnBL and AUDH, were significantly larger in male(p<0.05). but, intermaxillary relations and spatial position of maxilla and mandible relative to cranial base were not different for both sex. 2. With the exception of upper and lower anterior crowding, lower arch width, upper arch length, AMR, male exhibited significantly larger measurements in model analysis (p<0.05). 3. Size differences of maxilla and mandible between openbite and non-openbite group were not significant(p>0.05). but openbite group showed significantly increased genial angle(p<0.05), FH-CoGo(p<0.01), FH-NA(p<0.01) and FH-NB, FH-NPog (p<0.05). 4. ALFH and PUDH were larger(p<0.05) in openbite group. this result served as compensation for the spatial position of mandible relative to cranial base. AUPUDH (p<0.001) and ALPLDH(p<0.05) were lower in openbite group. upper anterior crowding was the only measurement which showed difference between openbite and non-openbite group(p<0.05). 5. For the purpose of classifying adult class n openbite and non-openbite group, multiple discriminant analysis was done genial angle, ALPLDH, AUPUDH, FH-NA were included in multiple discriminant equation. 39 cases($92.86\%$) were correctly classified when applied to the sample used in this study.

• The korean journal of orthodontics
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• v.33 no.6 s.101
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• pp.485-497
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• 2003

The form and function of the craniofacial structure critically depend on genetic information. With recent advances in the molecular technology, genes that are important for normal growth and morphogenesis of the craniofacial skeleton are being rapidly uncovered, shaping up modem craniofacial biology. One of them is fibroblast growth factor receptor 2 (FGFR2). Specific point mutations in the. FGFR2 gene have been linked to Apert syndrome, which is characterized by premature closure of cranial sutures and craniofacial anomalies as well as limb deformities. To study pathogenic mechanisms underlying craniosynostosis phenotype of Apert syndrome, we used a transgenic approach; an FGFR2 minigene construct containing an Apert mutation (a point mutation that substitute proline at the position 253 to arginine; P253R) was introduced into fertilized mouse germ cells by DNA microinjection. The injected cells were then allowed to develop into transgenic mice. We used a bone-specific promoter (a DNA fragment from the type I collagen gene) to confine the expression of mutant FGFR2 gene to the bone tissue, and asked whether expression of mutant FGFR2 in bone is sufficient to cause the craniosynostosis phenotype in mice. Initial characterization of these mice shows prematurely closed cranial sutures with facial deformities expected from Apert patients. We also demonstrate that the transgene produces mutant FGFR2 protein with increased functional activities. Having this useful mouse model, we now can ask questions regarding the role of FGFR2 in normal and abnormal development of cranial bones and sutures.

• The korean journal of orthodontics
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• v.33 no.6 s.101
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• pp.419-435
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• 2003

The purpose of this study was to evaluate growth changes and skeletal characteristics of Korean children with Class III malocclusions from 10 to 14 years of skeletal age. Radiographs of 60 children with Class III malocclusion and 60 normal controls were assessed. Both groups were subdivided into 6 samples according to sex and skeletal age. Skeletal age was assessed using handwrist X-rays using the Greulich and Pyle norms. The Krogman-Walker plane (occipitale-maxillon) through Sella was used as a reference plane in this study with x-axis perpendicular to the x-axis. Sir Student t-tests were conducted to compare the control group with the Class III group according to each gender a:nd age. The characteristics of Class III malocclusion group compared to the control group included shorter anterior and posterior cranial base, shorter and retrusive maxilla, forger mandible, increased molar-incisor distance, retroclined lower incisors, labially proclined upper incisors, and anteriorly located mandibular molar, smaller upper and middle facial depth, and larger lower facial depth. Landmarks representing facial depth, size of maxilla and mandible, and their AP relationship including anterior facial height indicate that growth characteristic was determined early in life. But growth Pattern of cranial base and some of the dental landmarks showed progressive divergence between Control and Class III groups with age. The position of the posterior border of the mandible was found to be significantly forward in both females and males by the age of 14 and at the anterior border in males and females at all ages. Hyperdivergent mandibular plane, changes in anterior segment of mandible, small anterior cranial base, and decrease in cranial base flexure was also noted.

• The korean journal of orthodontics
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• v.35 no.3 s.110
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• pp.182-195
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• 2005

The purpose of this retrospective study was to estimate the pretreatment characteristics of growing patients with Class II malocclusion. who had been treated with maxillary second molar extractions The sample comprised of 51 subjects; 18 subjects were classified into the molar extraction group, and 33 subjects were treated without extraction and classified into the nonextraction group. Pretreatment lateral cephalograms were calculated and analyzed by independent t-test and stepwise discriminant analysis. In measurements for skeletal pattern, no anteroposterior measurements and proportions of various vertical dimensions were significantly different. and only some measurements such as $AB-MP(^{\circ)$, Na-We(mm), AVD (mm) were significantly different between the two treatment groups (p<0.05). In measurements for dentoalveolar pattern. some measurements, which were related to the position and angulation of the upper and lower permanent first molars, and the angulation of the upper third molars, were significantly different between the two treatment groups In particular, the maxillary second molar extraction group exhibited more mesial angulation of maxillary first molar to the occlusal plane.

• The korean journal of orthodontics
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• v.40 no.2
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• pp.106-114
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• 2010

Objective: The aim of this experimental study was to evaluate the effects of direct electrical current stimulation (DECS) on bone regeneration in response to an expansion of the inter-premaxillary suture in the rat. Methods: Sixteen 50 - 60 days old Wistar male rats were separated into two equal groups (control and experimental). Both groups were subjected to expansion, and 30-gram of force was applied to the maxillary incisors with helical-spring. In the experimental group, two metallic-screws were placed at lateral parts of the maxillary segments. Electrodes were connected to the screws. The device was activated with current adjustment to measure $10{\mu}A$ continuously and the current was monitored daily during the expansion and early-retention phase. Bone regeneration in the sutural area was histomorphometrically evaluated including new-bone area (${\mu}m^2$), bone perimeter (${\mu}m$), feret's diameter (${\mu}m$) and newly formed bone (%) parameters. Kruskal-Wallis rank and Mann-Whitney U tests were used for statistical evaluation at p < 0.05 level. Results: Statistical analysis showed significant differences between groups for all investigated histomorphometric parameters. New bone area (p = 0.002), bone perimeter (p = 0.004), feret's diameter (p = 0.002) and newly formed bone percentage (p = 0.002) measurements were significantly higher in the experimental group than the control group. Bone histomorphometric measurements revealed that bone architecture in the DECS group was improved. Conclusions: The application of DECS to an orthopedically expanded inter-premaxillary suture area during the early retention phase stimulated the formation of new bone.

• The korean journal of orthodontics
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• v.10 no.1
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• pp.71-79
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• 1980

The purpose of this study was (1) to determine the prevalence of some causes by which dental occlusion might be affected , (2) to determine the prevalence of malocclusion, and types of molar, vertical incisor and horizontal incisor relationships, and (3) to examine the sex difference in the prevalence ratios, and (4) to determine the between-examiner differences in assessing types of dental occlusion. The material consisted of 1281 males and 811 females, total 2091 persons, aged 17 to 21 years. Two examiners who were graduate students in the orthodontic course, examined independently dental occlusion of the material. Before calculating the statistics, the subjects consisted of 156 mates and 164 females, total 320 persons, haying any one or more causes suspected to affect dental occlusion, was eliminated. Then the remained subjects, 1124 males and 647 females, total 1771 persons, were assessed. The results were as follows 1. The prevalence of some causes by which dental occlusion might be affected was 15.32 per cent. The missing rate of any one or more first molars was 8.85 percent, that of any one or more teeth positioned anterior to the first molar was 3.83 per cent. The prevalence of crossbite of the first molar was 0.48 per cent, that of retained primary teeth was 0.77 percent, and that of orthodontic treatment was 0.43 per cent. 8. The rate of between-examiner difference was 12.53 per cent in assessing the types of molar relationship, 18.86 percent in assessing the types of horizontal incisor relationship, and 26.37 percent in assessing the types of horizontal incisor relationship. 3. There was no sex difference in the prevalence ratios of the types of molar relationship. The prevalence of Class I molar relationship was 80.91 percent, that of Class II was 5,03, that of Class II subdivision was 4.01, Percent, that of Class III was 5.99 percent and that of Class III subdivision was 4.07 percent. 4. In the prevalence of the types of horizontal incisor relationship, there were no sex differences except that of Class II division 2. The prevalence of Class I horizontal incisor relationship was 73.12 percent, that of Class II division t was 12.03 percent, that of Class II division 2 was 6.58 percent in male and 4.33 percent in female, and that of Class III was 9.09 percent. 5. In the prevalence of the types of vertical incisor relationship, there were no sex differences except that of deep bite, The prevalence of open bite was 2.20 per cent, that of edge-to-edge bite was 9.15 percent, that of normal bite was 76,34 percent, and that of deep bite was 14.15 percent in male and 9.12 percent in female. 6. There was no sex difference in the prevalence of malocclusion the prevalence of malocclusion was 82.67 percent and that of normal occlusion was 17.33 percent. 7. There was a tendency that when Class I molar relationship changed to Class II, incisor relationships were to be larger overjet or upright upper incisors and deep bite, but when that changed to Class III molar relationship, these were to be cross bite and openbite.

• The korean journal of orthodontics
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• v.28 no.1 s.66
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• pp.85-97
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• 1998

The purpose of this study was to observe the effects of sodium fluoride on the bony repair and regeneration processes after the rapid palatal expansion in the growing dogs. Eighteen dogs were divided into experimental and control groups. They were in the late mixed dentition. The rapid Palatal expansion was undertaken in all the animals($180^{\circ}$ turn/day) for ten days. The animals were sacrificed on 0, 15 and 45 days after the finish of expansion. One mg NaF/kg of body weight/day were given orally to the experimental group. Blood samples were drawn before and after expansion and the se겨m calcium, phosphate and alkaline phosphatase level were measured. The undecalcified bone section of midpalatal suture area was made, and observed under the light microscopy The results were as follows ; 1. The day after expansion, the infiltration of inflammatory cells were prominent and the new bone formation started at the edges of the two palatal plates bodering the midpalatal suture in both groups. Especially, the newly formed osteoid were very extensive and the osteoblasts lining the osteoid were very active in the experimental group. 2. At fifteen days after expansion, the active osteoblasts lining the osteold at the surface of trabecular bony spicules and active new bone formation were observed in the both groups. However, the cellular activity and new bone formation were more prominent In the experimental group. 3. At forty five days after expansion, the continuous osteoid and new bone formation and active osteoblasts were observed in the experimental group. But these phenomena were not observed in the control group. In the control group, the numerous osteoclasts were adjacent midpalatal suture and the bony remodeling process was begun. The serum alkaline phosphatase level was maintained highly in the experimental group, but decreased in the control. According to the above results, the author reached the conclusion that sodium fluoride has the stimulation effects on the osteoid production of the osteoblasts during the healing process after the rapid Palatal expansion more continuously.

• The korean journal of orthodontics
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• v.28 no.1 s.66
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• pp.1-15
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• 1998

Adult wound healing is accompanied with inflammation and eventual scar formation, whereas fetal wounds heal rapidly by mesenchymal proliferation without significant inflammatory cell participation and with minimal or no scar formation. The cellular mechanisms underlying these differing forms of wound healing are unknown but the extracellualr matrix through its effects on cell function, may play a key role. Therefore the purpose of this study is to investigate the spatial and temporal deposition of several component of extracellular matrix, which are known to be involved with scar formation, in the artificially created cleft lip wound healing of fetuses. The author had undergone hysterotomy and created cleft lip-like defects on fetuses of New Zealand White Rabbit in mid-third trimester(24 days). Fetuses were divided into the repaired group, the unrepaired group and the sham-operated control group. At 1, 2, 3, 5, 7 days after procedure, fetuses were obtained by Caeserem section. After documenting the viability of fetuses, they were photographed to compare size and facial morphology and sectioned for histological examination by H & E stain and spatial and temporal deposition of collagen typeI, III, IV, V and fibronectit laminin by immunohistochemical method. The findings are summarized as follows 1. There were lack of inflammation in the repaired and the unrepaired group during experimental periods. 2. The reepithelialization of the unrepaired group was slower than that of the repaired group. 3. Collagen I, III, V were found from post-op. third day. There were no difference of distribution in the control, the repaired and the unrepaired group. Collagen types I, III, V were present in all groups with restoration of the normal collagen pattern in the fetus. This implies that lack of scarring in fetal wounds is due to the difference of collagen organization pattern within wound and not simply lack of collagen formation. 4. Collagen IV was slightly increased at post-op. third day and decreased after post-op. fifth day. Eventually there were no differences in the control, the repaired and the unrepaired group. Lminin was found at post-op. fifth day and maintained staining density until post-op. seventh day. There were no differences in the control, the repaired and the unrepaired group. According to staining of laminin and collagen type IV in epithelial basement membrane, formation of epithelial basement membrane was not completed until reepithelialization was finished. 5. According to staining of laminin and collagen type IV, there were no increase of neovascularity in the repaired and the unrepaired group. 6. Fibronectin was increased until post-op. third day at fibrin clot, wound base and margin and decreased after post-op. fifth day. Eventually, there were no differences in the control, the repaired and the unrepaired group. So it implies fibronectin plays a role as provisional matrix for fetal wound healing.

• The korean journal of orthodontics
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• v.30 no.2 s.79
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• pp.205-214
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• 2000

Recently, the magnetic force has been considered as a method for a more efficient tooth movement. The purpose of this study was to evaluate the effects of different static magnetic fields of Nd-Fe-B magnet on MC3T3-E1 cells by measuring the alkaline phosphatase activity and observing the amount of stained alkaline phosphatase. For measuring of alkaline phosphatase activity, MC3T3-E1 cells were seeded in first and third row of 12 well culture plates. And Nd-Fe-B magnets were positioned under the first column of first and third row to apply different static magnetic fields(first column:100mT ; second column:4.6mT ; third column:0.5mT ; forth column:0.0mT) to the cells for 7, 13, 19, and 25 days. For staining of alkaline phosphatase, MC3T3-E1 cells were seeded in 100mm culture plates. And Nd-Fe-B magnets were positioned under the corner of plates to apply different static magnetic fields(magnet side:100mT : the opposite side:0.5mT) to the cells for 7, 13, 19, and 25 days. The results were as follows : 1. ALP activity was increased until day 19 in biochemical determination as well as in histochemical staining, 2. The application of higher magnetic field(100mT) suppressed ALP activity at day 13, 19, 25. On the contrary, the application of the lower magnetic field(4.6mT, 0.5mT) significantly enhanced the ALP activity. 3. Consistent with enzyme assay, histochemical staining of ALP also demonstrated that higher magnetic field(100mT) suppressed ALP activity, lower one(0.5mT) enhanced.