• The korean journal of orthodontics
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• v.36 no.6
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• pp.412-421
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• 2006

Objective: The result of finite element analysis depends on material properties, structural expression, density of element, and boundar or loading conditions. To represent proper elastic behavior, a finite element model was made using Hounsfield unit (HU) values in CT images. Methods: A 13 year 6 month old male was used as the subject. A 3 dimensional visualizing program, Mimics, was used to build a 3D object from the DICOM file which was acquired from the CT images. Model 1 was established by giving 24 material properties according to HU. Model 2 was constructed by the conventional method which provides 2 material properties. Protraction force of 500g was applied at a 45 degree downward angle from Frankfort horizontal (FH) plane. Results: Model 1 showed a more flexible response on the first premolar region which had more forward and downward movement of the maxillary anterior segment. Maxilla was bent on the sagittal plane and frontal plane. Model 2 revealed less movement in all directions. It moved downward on the anterior part and upward on the posterior part, which is clockwise rotation of the maxilla. Conclusion: These results signify that different outcomes of finite element analysis can occur according to the given material properties and it is recommended to use HU values for more accurate results.

• The korean journal of orthodontics
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• v.26 no.5 s.58
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• pp.547-556
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• 1996

The purpose of this study was to evaluate the skeletal, dental and soft tissue profile changes following the face mask therapy in growing skeletal class III malocclusion patients. The fifteen patients with the good results were selected among the patients who visited the Department of Orthodontics in Seoul National University Hospital. The mean age was 10.63(range 7.25-13.25) years and the mean treatment duration was 9.84(range 2.00-27.00) months. Lateral cephalograms were taken just before and after face mask application. After tracing the cephalograms, thirty five items(twety angular and fifteen linear) were measured. The differences before and after the face mask therapy were compared statistically by the paired t-test(p<0.05). The results were as follows : SNA and Co-A(effective maxillary length) increased significantly after using the face mask(p<0.001), which reflects the orthopedic changes of maxilla. SNB and Co-Gn(effective mandibular length) also showed an increase(p<0.01), which may be a result of the strong growth trends of the samples. FMA, SN-GoGn and Y-axis angle increased significantly(p<0.01), which means the backward and downward rotation of the mandible. This positional change seemed to have compensated an increase of effective mandibular length. There was no statistically significant difference in angulation of upper and lower incisors between pre-treatment and post-treatment(p>0.05). In soft tissue profile, the upper lip was positioned anteriorly(p<0.01) after treatment and approximated to the normal standards.

• The korean journal of orthodontics
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• v.37 no.3 s.122
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• pp.231-240
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• 2007

Objective: The purpose of this study was to investigate the maxillary protraction effects of the Tandem Traction Bow Appliance (TTBA), a new appliance devised several years ago for the treatment of growing skeletal Class III patients. Methods: Participants were 88 Korean children (42 boys, 46 girls) with skeletal Class III malocclusion treated with TTBA at the orthodontic clinic of Ewha Womans University Mokdong Hospital. Mean age at the start of treatment was 7.5 years${\pm}$1.5 years. Mean treatment periods were $13{\pm}3$ months. Pretreatment and posttreatment lateral cephalograms were traced and superimposed by the same investigator and analyzed by modified McNamara analysis and pitchfork analysis. Changes were evaluated with paired t-tests at a significance level of p<0.05. Results: The maxilla and maxillary dentition moved forward. The mandible moved backward, although not significantly; and the mandibular dentition moved forward. The net dental changes combined with the apical base change resulted in a favorable total molar relationship correction. Net dental movement was 26% and the apical base change 74% of the total molar relationship correction. Conclusion: These results suggest that TTBA has a maxillary protraction effect that can be useful in the treatment of growing skeletal Class III malocclusion with maxillary deficiency.

• The korean journal of orthodontics
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• v.26 no.4
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• pp.341-348
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• 1996

The efficiency of maxillary canine retraction by means of sliding mechanics along an 0.016 continuous labial arch and an 0.009 inch in diameter with a lumen of 0.030 inch NiTi closed coil spring was compared with that using the same NiTi closed coil spring and Molar Anchoring Spring(MAS) which was designed by author. MAS was made of .017" X .025" TMA wire and was given 60 degree tip-back bend on the wire close to the molar tube. This study was designed to investigate molar and canine root control during retraction into an extraction site with continuous arch wire system. Two techniques were tested with a continuous arch model embedded in a photoelastic resin. A photoelastic model was employed to visualize the effects of forces applied to canine and molar by two retraction mechanics. With the aid of polarized light, stresses were viewed as colored fringes. The photoelastic overview of the upper right quadrant showed that stress concentrations were observed in its photoelastic model. The obtained results were as follows. 1. Higher concentration of compression can be seen clearly at the distal curvature of the canine and mesial curvature of the molar and premolar when NiTi closed coil spring was applied only, which means severe anchorage loss of the molar and uncontrolled tipping of the canine. 2. The least level compression was presented at the mesial root area of the molar and premolar, and mesial root area of the canine when NiTi closed coil spring and MAS were used simultaneously. Especially mesial alveolar crest region of the canine was shown moderate level of compression that means MAS can be used as a appliance for anchorage control and prevention of canine extrusion and uncontrolled tipping during canine retraction.

• The korean journal of orthodontics
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• v.14 no.1
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• pp.15-24
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• 1984

The purpose of this study was to evaluate the effect of O.M.A on Angle's class III malocclusion. The author analysed the data obtained from pre- and post-treatment lateral cephalograms. The results obtained were as follows : 1. Forward growth of maxillary complex was accomplished. 2. The mandible showed few morphological changes in the presence of downward and backward swing. 3. It was assumed that the hooks attached to the intraoral appliance should be placed as far frontally as possibie. 4. Relations of the upper and lower jaws were improved resulting in better facial profiles.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.13 no.1
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• pp.117-127
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• 1991

When open reduction of maxilla fractures is postponed due to concurrent life-threatening injuries, delayed union may result with malunion or nonunion. If delayed malunion is occurred, significant facial deformity may result, including a dished-out face, irregular retromaxillism with Angle's class III malocclusion, open anterior bite, nasal collapse, telecanthus and malar flattening. The treatment planning for this problem includes cephalometric evaluation anterior and lateral tomograms, dental casts, orthodontic planning, dental planning and use of impression tray to rupture the fibrous tissue casts, orthodontic planning, dental planning and use of impression tray to rupture the fibrous tissue attachment at the fracture site. In this paper, one case presented a 58-year-old female patient with maxilla retrusion after comminuted fracture, who was treated with orthodontic methods of maxillary protraction headgear and Plaster headcap, whereas the other two cases were about male patients who were treated principally with surgically open reduction or Le Fort I-controlled transverse osteotomy with iliac bone graft.

• The korean journal of orthodontics
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• v.37 no.2 s.121
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• pp.98-113
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• 2007

Objective: The purpose of this study was to evaluate the displacement pattern and the stress distribution shown on a finite element model 3-D visualization of a dry human skull using CT during the retraction of upper anterior teeth. Methods: Experimental groups were differentiated into 8 groups according to corticotomy, anchorage (buccal: mini implant between the maxillary second premolar and first molar and second premolar reinforced with a mini Implant, palatal: mini implant between the maxillary first molar and second molar and mini implant on the midpalatal suture) and force application point (use of a power arm or not). Results: In cases where anterior teeth were retracted by a conventional T-loop arch wire, the anterior teeth tipped more postero-inferiorly and the posterior teeth moved slightly in a mesial direction. In cases where anterior teeth were retracted with corticotomy, the stress at the anterior bone segment was distributed widely and showed a smaller degree of tipping movement of the anterior teeth, but with a greater amount of displacement. In cases where anterior teeth were retracted from the buccal side with force applied to the mini implant placed between the maxillary second premolar and the first molar to the canine power arm, it showed that a smaller degree of tipping movement was generated than when force was applied to the second premolar reinforced with a mini implant from the canine bracket. In cases where anterior teeth were retracted from the palatal side with force applied to the mini implant on the midpalatal suture, it resulted in a greater degree of tipping movement than when force was applied to the mini implant between the maxillary first and second molars. Conclusion: The results of this study verifies the effects of corticotomies and the effects of controlling orthodontic force vectors during tooth movement.

• Journal of Technology Innovation
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• v.28 no.4
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• pp.97-126
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• 2020

This study evaluated its potentials by quantitatively analyzing the national economic impact of the smart home-related industry, which is attracting attention as a core industry of the 4th industrial revolution. For the analysis, the smart home-related industries were classified into manufacturing and service industries through a literature review of the previous studies. Using the 2018 input-output table, this paper analyzed linkage effects between industries as well as spillover effects in the production, value-added, employment and job. As a result, the smart home manufacturing and service sectors showed a higher spillover effect in value-added than other industries in each industrial field. In the smart home industry, the spillover effects of manufacturing sector to service sector are larger than those of service sector to manufacturing sector. Moreover, it was confirmed that smart home industry was highly related to not only the technology-intensive industry, but also the service sector for smart cities, smart cars, Fin-tech, and etc. On the other hand, the smart home manufacturing sector is a final demanding industry with relatively higher backward linkage effect than forward linkage effect. In the smart home service sector, the forward linkage effect was relatively high compared with the backward linkage effect, indicating that it was an industry with a high supply function to other industries.

• The korean journal of orthodontics
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• v.24 no.2
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• pp.349-366
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• 1994

The method of treatment in skeletal Class III malocclusion must be chosen according to an etiology and timing of the treatment. Maxillry protraction has been used as an effective treatment method in growing children with maxillary deficiency. The efficacy of maxillary protraction has been viewed as a result of downward-backward displacement of mandible and compensatory dental displacement during the treatment rather than forward -downward growth of maxilla itself. In this study, 104 subjects treated with maxllary protraction, and 19 males and 21 females with known annual growth amount have been chosen longitudinally as treated group and normal group, respectively. And changes in position of maxilla, mandible and dentition have been comparatively analyzed on the lateral cephalometric radiographs by age. The results were as follows : 1. Treated group showed more forward movement of maxilla compare to the normal group and the mandible displaced backward compare to the normal group. 2. Downward movement of maxilla in treated group was similar to that of normal group with statistical signigicance in female 12 year old group and downward movement of mandible in treated group was similar to that of normal group. 3. In treated group, maxillary central incisor moved more forward than the normal group with statistical significance in male 8, 10 year-old groups and female 8, 9, 10 year-old groups. In treated group, downward movement of maxillary central incisor was similar to that of the normal group with statistical significance in male and female 7,8 year-old groups. Considering the above results and the duration of the treatment, the forward movement of maxilla due to maxillary protraction was effective compared to normal growth amount of the normal group.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.4
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• pp.675-681
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• 2005

The Horseshoe appliance was introduced by Dr. Schwarz, and it is used to correct sagittal relationships by elastic force in class III malocclusion. It minimizes the increment of lower anterior facial height and allows the mandible to be repositioned harmoniously with the soft tissue and muscle matrix of the jaw It has the advantages of better patient cooperation, easier construction, and more effective modification. In the patients who were treated with Horseshoe appliance, forward growth of maxilla and counterclockwise rotation of occlusal plane with labioversion of maxillary incisors and linguoversion of mandibular incisors were obtained. Minimum downward and backward rotation of mandible was accepted, so increasing of lower anterior facial height was minimized.