• The korean journal of orthodontics
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• v.28 no.1 s.66
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• pp.61-74
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• 1998

The Purpose of this study was to investigate the stress distribution and tooth displacement at the initial phase produced by 5 types of molar uprighting springs using finite element method. The three dimensional finite element model of lower dentition, bone and springs was composed of 5083 elements and 2071 nodes. The results were as follows: 1. In case of helical spring and root spring, intrusion of lower canine and first premolar were observed md distal tipping, translation and extrusion of lower second molar were observed. 2. In case of T-loop, modified T-loop and box loop, intrusion and distal translation of lower second premolar were observed, and the largest crown distal tipping and translation of lower second molar were observed in T-loop and the smallest were observed in box loop. 3. In case of T-loop with cinch-bact crown distal tipping and translation of lower second molar were decreased, but extrusion was also decreased. 4. With increase of activation in T-loop, mesial translation and won distal tipping of lower second molar were increased and edentulous space was closing, but distal translation of second premolar was also increased. 5. With increase of tip-back bend in T--loop, distal tipping and translation of lower second molar were increased, but extrusion was also increased more largely.

• The korean journal of orthodontics
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• v.40 no.4
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• pp.250-259
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• 2010

Objective: Intraoral noncompliance upper molar distalization techniques have gained in popularity and have subsequently found to be successful in Class II correction. The aim of the present study was to introduce a screw supported intraoral distalization appliance and investigate its efficiency. Methods: Twenty-one subjects (11 females, 10 males; average age of 14.9 years) with Angle Class II malocclusion participated in this study. Two screws were inserted behind the incisive foramen and immediately loaded to distalize the upper first molars. An intraoral screw supported distalization appliance was used to distalize the upper molars in order to achieve a Class I molar relationship. Skeletal and dental changes were evaluated using cephalometric and three-dimensional (3D) model analysis. Results: Upper molars were distalized 3.95 mm on average and a Class I molar relationship was achieved without any anchorage loss. The upper molars were tipped only $1.49^{\circ}$ and the upper right and left molars were rotated only $0.54^{\circ}$ and $0.74^{\circ}$ respectively which were statistically non-significant (p > 0.05). Conclusions: The newly designed screw supported noncompliance distalization appliance was found to be an effective device for achieving bodily molar distalization without any anchorage loss.

• The korean journal of orthodontics
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• v.28 no.3 s.68
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• pp.431-440
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• 1998

While periodontal disease results in the extrusion of upper incisors with interdental spacing in adult patient, the intrusive movement should be executed for the rehabilitation in terms of esthetics and function. The present study was peformed to investigate the periodontal response following orthodontic intrusion of teeth with infrabony pocket. Bone defect and periodontal disease were produced adjacent to the both maxillary second lateral incisors in four adult dogs. Four weeks later, a flap operation was performed to eliminate inflammation and a reference notch was made on the root surface at the level of bottom of each defect. Two weeks after periodontal surgery, 4 weeks of intrusion and subsequent another 4 weeks of retention was executed on the right side of incisors while left incisors served as the control. Through the histologic analysis, following results were obtained. 1. Histologic section of control side showed the reduction of pocket depth after flap operation. However, the status of long junctional epithelium was observed while new connective tissue attachment occurred in a small area adjacent newly formed cementum 2. Epithelial attachment was less around the intruded incisor while new connective tissue attachment was much more compared to the control side. 3. Plenty of cells were observed in the connective tissue around the reference notch of the intruded incisor and the degree of the new cementum formation was higher in the intruded incisor than the control. The results of the present study suggested that an orthodontic intrusion of periodontally involved and extruded incisors could be carried out with a desirable periodontal response, provided that inflammation is under control.

• The korean journal of orthodontics
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• v.28 no.6 s.71
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• pp.915-926
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• 1998

The cytoskeleton has been shown to form a network, connecting the extracelluar matrix via integrin with the nucleus and the cytoplasmic constituents of the cell. It is therefore assumed that the cytoskeleton may mediate signals generated by perturbations originating in the matrix. The purpose of this study is to examine the effect of cytoskeletal change on osteoblastic cell activities. The author cultured osteoblastic cells obtained from neonatal mouse calvaria. The cells were teated with cytochalasin B(CB) or colchicine (COL) at four concentrations for 3 hours and after another 24 hours the conditioned media was collected and assayed for prostaglandin $E_2\;(PGE_2)$, interleukin-6(IL-6), tumor necrosis factor-$\alpha$ (TNF-$\alpha$) and matrix metalloproteinase-1(MMP-1). In addition, the cytoskeletal protein actin were observed by immuno-fluorescence. The results were as follows: 1. The production of $PGE_2$ showed the tendency to be increased in CB-treated group. $PGE_2$ was increased in COL-treated group dose-dependantly, 2. IL-6 production, in CB-treated group, was increased, except at 1.0 ${\mu}g/ml$. IL-6 was induced in COL-treated group. 3. TNF-$\alpha$ production was increased in CB-treated group, except at 1.0 ${\mu}g/ml$, and in COL-treated group, that was increased. 4. The MMP-1 production was decreased in CB-treated soup and was not changed in COL-treated group, which could be selectively visualized by immunoblotting with monospecific antibody. 5. The cytoskeletal actin stress fibers were disappeared and the cells showed to be rounded in CB-treated group. These results indicated that there are a relationship between the cytoskeletal rearrangements and osteoblastic cell activities, especially in release of paracrine/autocrine factors, such as $PGE_2$, IL-6, and TNF-$\alpha$.

• The korean journal of orthodontics
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• v.39 no.5
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• pp.337-347
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• 2009

Objective: The aim of this study was to evaluate the effects of vitamin E ($\alpha$-tocopherol) administration on bone formation in response to expansion of the inter-premaxillary suture, in rats, histomorphometrically. Methods: Thirty 50 - 60 day old Wistar rats were separated into five equal groups (one control and four experimental). All groups were subjected to inter-premaxilla expansion with 50-gram of force. Six control animals received saline solution (Group I) and three experimental groups were treated with a single dose of $\alpha$-tocopherol injected into the inter-premaxillary suture after one day after appliance placement (Group II: 2 mg/kg; Group III: 10 mg/kg; and Group IV: 50 mg/kg). A further group of six animals received three injections of 10 mg/kg $\alpha$-tocopherol, one each on days 3, 6, and 9 (Group V). Bone formation in the suture was evaluated by bone histomorphometry. Kruskal-Wallis rank and Mann-Whitney U tests were used for statistical evaluation at p < 0.05 level. Results: New bone area, bone perimeter, feret's diameter and newly formed bone measurements were significantly higher in the experimental groups than the control (p < 0.001). Bone architecture in $\alpha$-tocopherol administrated groups was improved, and bone formation during the expansion period was stimulated significantly, in a dose-dependent manner. Conclusions: The application of $\alpha$-tocopherol during the early stages to orthopedically expanded inter-premaxillary suture areas may stimulate bone formation and shorten the retention period, in rats.

• The korean journal of orthodontics
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• v.39 no.5
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• pp.310-319
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• 2009

Objective: NiTi closed coil springs were reported to have relatively constant unloading forces. However, the characteristics of NiTi closed coil springs from various manufacturers have not been elucidated. The purpose of this study was to compare load-deflection characteristics of various NiTi closed coil springs and to find out the optimal range of extension. Methods: Seven kinds of NiTi closed coil springs from five manufacturers were tested. Load deflection curves were obtained at extension ranges from 2 mm to 30 mm. Also, springs were kept extended during a 4 week period, and then load deflection curves were obtained again. Results: Sentalloy (Tomy) and Jinsung blue (Jinsung) showed superelasticity in every extension ranges tested and showed plastic deformation of less than 1 mm. Ni-Ti (Ormco) showed superelasticity only after the springs were extended at or more than 10 mm, thereby meaning that clinicians should extend these springs at or more than 10 mm to utilize the superelasticity. Orthonol (RMO) and Nitanium (Ortho Organizers) did not show superelasticity. After 4 weeks of extension, all springs showed plastic deformation less than 1 mm when the extension was at or under 25 mm. Conclusions: The superelastic behavior of NiTi closed springs were different among various NiTi spring products, and some NiTi closed springs failed to show superelasticity.

• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.4
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• pp.265-277
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• 2014

Purpose: The purpose of this study was to investigate the differences of displacement pattern depending on type of sliding jig and application method during maxillary molar distalization with temporary anchorage devices (TADs). Materials and Methods: Maxilla with normal tooth size and arch shape was selected to create a 3-dimensional finite element model, which included the bracket, orthodontic main archwire, removable sliding jig (R-jig). The orthodontic mini-implant anchorage was set 8 mm superiorly from main archwire, buccally between the second premolar and first molar. The base experimental design was Condition 1, which was composed $0.019{\times}0.025$ inch stainless steel (SS) of wire size of R-jig, 200 gm force, un-tied state. And the other designs varied to wire size of R-jig, magnitude of force. The results are as follows. Results: As the wire size of R-jig was increased, the deformation of R-jig was decreased. However, the displacement of second molar wasn't different each other. As the force to second molar was increased, the more displacement of second molar was observed, and the more distal tipping movement, vetical displacement was observed. Conclusion: R-jig can get distal teeth movement in orthodontic treatment without side effects.

• The korean journal of orthodontics
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• v.38 no.3
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• pp.187-201
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• 2008

Objective: The aim of this study was to determine whether cortical punching stimulates the expression of matrix metalloproteinase-1, -8, and -13 in orthodontic tooth movement in rats. Methods: A total of 32 male sprague-dawley rats at 15 weeks old were divided into two groups of 16 rats each, to form the tooth movement with cortical punching (TMC) group and tooth movement only (TM) group. A total of 20 gm of orthodontic force was applied to rat incisors to cause experimental tooth movement. Cortical punching was performed on the palatal side near the central incisor with a 1.0 mm width microscrew in the TMC group. The duration of tooth movement was 1, 4, 7, and 14 days. Results: Measurements of the mRNA expression were selected as the means to determine the identification of expression of MMP-1, -8, and -13. In the TMC group, the expression of collagen type I was greater than that of the TM group from day 4 to day 14. Expression of TIMP-1 in the TM group was greater than that of the TMC group in the pressure side of PDL and alveolar bone cell at day 4. In the TMC group, TIMP-1 was expressed at the osteoclast, but not at the tooth surface of the TM group at day 14, Maximum induction of the mRNA of MMP-1 was observed on day 4 in the TMC group, but it was observed on day 7 in the TM group. MMP-8 mRNA of the TMC group was twice greater than that of the TM group at f days. In the TMC group, maximum induction of MMP-13 mRNA was observed on day 1. Conclusions: These findings suggested that cortical punching can stimulate remodeling of PDL and alveolar bone connective tissues during experimental orthodontic tooth movement in rats.

• The korean journal of orthodontics
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• v.33 no.3 s.98
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• pp.169-183
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• 2003

Tooth movement by orthodontic force effects great tissue changes within the periodontium, especially by shifting the blood flow in the pressure side and resulting in a hypoxic state of low oxygen tension. The aim of this study is to elucidate the possible mechanism of apoptosis in response to hypoxia in MC3T3El osteoblasts, the main cells in bone remodeling during orthodontic tooth movement. MC3T3El osteoblasts under hypoxic conditions ($2\%$ orygen) resulted in apoptosis in a time-dependent manner as estimated by DNA fragmentation assay and nuclear morphology stained with fluorescent dye, Hoechst 33258. Pretreatment with Z-VAD-FMK, a pancaspase inhibitor, or Z-DEVD-CHO, a specific caspase-3 inhibitor, completely suppressed the DNA ladder in response to hypoxia. An increase in caspase-3-like protease (DEVDase) activity was observed during apoptosis, but no caspase-1 activity (YVADase) was detected. To confirm what caspases are involved in apoptosis, Western blot analysis was performed using anti-caspase-3 or -6 antibodies. The 10-kDa protein, corresponding to the active products of caspase-3, and the 10-kDa protein of the active protein of caspase-6 were generated in hypoxia-challenged cells in which the processing of the full length form of caspase-3 and -6 was evident. While a time course similar to this caspase-3 and -6 activation was evident, hypoxic stress caused the cleavage of lamin A, which was typical of caspase-6 activity. In addition, the stress elicited the release of cytochrome c into the cytosol during apoptosis. Furthermore, we observed that pre-treatment with SB203580, a selective p38 mitogen activated protein kinase inhibitor, attenuated the hypoxia-induced apoptosis. The addition of SB203S80 suppressed caspase-3 and -6-like protease activity by hypoxia up to $50\%$. In contrast, PD98059 had no effect on the hypoxia-induced apoptosis. To confirm the involvement of MAP kinase, JNK/SAPK, ERK, or p38 kinase assay was performed. Although p38 MAPK was activated in response to hypoxic treatment, the other MAPK -JNK/SAPK or ERK- was either only modestly activated or not at all. These results suggest that p38 MAPK is involved in hypoxia-induced apoptosis in MC3T3El osteoblasts.

• The korean journal of orthodontics
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• v.27 no.4 s.63
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• pp.549-557
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• 1997

This study was designed to investigate the attrition pattern in Angle Class III malocclusion with facial asymmetry. The sample consisted of three groups, the 20 subjects of normal occlusion group(Group I), the 12 subjects of class III malocclusion without facial asymmetry group(Group II) and 17 subjects of Class III malocclusion with facial asymmetry group(Group III). Attrition areas from canine to second molar on both sides in upper and lower arch, totally twenty, was marked by pencil and mesured by computer system(INTERGRAPH CO. USA) 2 times and the average value was used for date processing. Attrition areas from canine to second molar on both sides in upper and lower arch, totally twenty, was marked by pencil and mesured by computer system(INTERGRAPH CO. USA) 2 times and the average value was used for date Processing. All attrition areas were measured 2 times and the average value was used for data processing The data were statistically analyzed by SAS program. The results of this study were as follows. 1. Total attrition area in Group I was larger than in Group II and III. 2. There was no significant difference in attrition area between right and left side in each group, but attrition area in Group III was larger than in Group I and II. 3. In Group I, Maxillary attrition area was larger than mandibular attrition area, but in Group ll and III, there was no significant difference in attrition area between maxilla and mandible. 4. In Group III, the attrition area of deviated side was target than undeviated side 5. There was no significant difference in attrition area between chewing side and non-chewing side in each group. 6. The total attrition area was unaffected by gender.