• The korean journal of orthodontics
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• v.31 no.1 s.84
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• pp.97-105
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• 2001

In many cases of orthodontic treatment the upper anterior teeth are retracted. Periodontal problems may arise during incisor retraction, if the amount of tooth movement and the amount of remodeling in the anterior cortical bone are not the same. Therefore in this study, to find out the relationship between the amount of tooth movement and the amount of bone remodeling during retraction of the upper anterior teeth, lateral cephalograms of 56 female patients over 18-year-old were taken before and after treatment. Among the 56 patients, two groups were divided according to the type of root movement during retraction. 26 patients mainly moved by tipping and 30 by bodily movement. The cephalograms taken before and after treatment were superimposed upon the true horizontal plane. In the Tip-Group, the horizontal bone remodeling/tooth movement ratio was 1:1.63, and in the Torque-Group it was 1:1.66. Because the amount of tooth movement and the amount of bone remodeling were not the same in both groups, in the Tip-Group the root apex moved away from the palatal cortical plate and closer to the labial cortical plate, whereas in the Torque-Group the root moved away from the labial cortical plate and closet to the palatal cortical plate. Therefore, there are limitations in the amount of incisor retraction in patients with a very thin anterior cortical plate in the maxilla, and in patients with severe skeletal discrepancies orthognathic surgery should be considered and when orthodontic camouflage treatment is the only possible method, the orthodontist must be aware of the limitations of treatment.

• The korean journal of orthodontics
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• v.34 no.2 s.103
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• pp.121-129
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• 2004

The purpose of this study was to photoelastically visualize 4he distribution of fortes transmitted to the alveolus and surrounding structures using three different types of headgear for the distal movement of the upper molars. A photoelastic maxillary model was made and three different directional forces applied, which were high-pull, straight-pull, and cervical-pull. Stress distribution was recorded through circular polariscope, and two-dimensional photoelastic stress analysis was performed according to isochromatic fringe characteristics. The results were as follows: 1. In the case of high-pull headgear bodily movement occurred in the medium- length outer bow, stress distribution in the apical region was 1st molar, 2nd premolar, lst premolar in sequence and there was no apparent difference. 2. In the case of straight-pull headgear, bodily movement occurred in the long outer bow and stress distribution in the apical region was heavy in the 1st molar, 2nd premolar, 1st premolar in sequence. But. there were no apparent differences according to the length of the outer bow. 3. In the case of cervical- pull headgear, bodily movement also occulted in 4he long outer bow, and apical stress of the premolar region was heaviest among other cases and apical stress of the 2nd premolar was heaviest in the short outer bow. In clinical situations, to achieve bodily movement of the upper 1st molars without modifying outer bow height, applying an outer bow length as long as the inner bow length in high-pull headgear and applying an outer bow length longer than the inner bow length in straight-pull, cervical-pull headgear are recommended.

• The korean journal of orthodontics
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• v.41 no.4
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• pp.237-254
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• 2011

Objective: The purpose of this study was to compare the displacement patterns shown by finite element analysis when the maxillary anterior segment was retracted from different orthodontic miniscrew positions and different lengths of lever arms in lingual continuous and segmented arch techniques. Methods: A three dimensional model was produced, the translation of teeth in both models was measured and individual displacement was calculated. Results: When traction was carried out from miniscrews in the palatal slope, lingual tipping of crowns and extrusion of the maxillary anterior segment were found in both continuous and segmented arches as the lever arms were made shorter. With miniscrews in the midpalatal suture area, the displacement patterns were similar to the palatal slope, but bodily movement of the upper incisors was observed in both continuous and segmented arches with the lever arm at 20 mm. When lever arms were longer, there was less extrusion of the incisors and more buccal displacement of the canines. Such displacement was shown less in the continuous arch than the segmented arch. The second premolar showed crown mesial tipping and intrusion, and the molars showed distal tipping in the continuous arch. The posterior segment was displaced three dimensionally in the segmented arch, but the amount of displacement was less than the continuous arch. Conclusions: It is recommended that lever arms of 20 mm in length be used for bodily movement of the anterior segment. Use of continuous or segmented arches affect the displacement patterns and induce differences in the amount of displacement.

• The korean journal of orthodontics
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• v.38 no.6
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• pp.376-387
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• 2008

Objective: The purpose of this study was to compare the three dimensional changes of tooth movement using four different types of maxillary molar distalization appliances; pendulum appliance (PD), mini-implant supported pendulum appliance (MPD), stainless steel open coil spring (SP) and mini-implant supported stainless steel open coil spring (MSP). Methods: These experiments were performed using the Calorific $machine^{(R)}$ which can simulate dynamic tooth movement. Computed tomography (CT) images of the experimental model were taken before and after tooth movement in 1 mm thicknesses and reconstructed into a three dimensional model using V-works $4.0^{TM}$. These reconstructed images were superimposed using Rapidform $2004^{TM}$ and the direction and amount of tooth movement were measured. Results: The mean reciprocal anchor loss ratio at the first premolar was 17 - 19% for the PD and SP groups. The appliances using mini-implants (MPD or MSP) resulted in less anchorage loss (7 - 8%). On application of a pendulum appliance or MPD, distalization was obtained by tipping rather than by bodily movement. Furthermore, the maxillary second molar tipped distally and bucally. But on application of MSP, distalization was achieved almost by bodily movement. Conclusions: Regarding tooth movement patterns during molar distalization, stainless steel open coil spring with indirect skeletal anchorage was relatively superior to other methods.

• The korean journal of orthodontics
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• v.36 no.1 s.114
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• pp.30-44
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• 2006

This study was performed to investigate the location of the ideal bracket positioning plane in lingual orthodontics using the three-dimensional finite element method. Displacement of the anterior teeth were evaluated according to the vertical and the angular movements of the bracket positioning plane. To achieve the ideal movement of anterior teeth in the lingual central plane, the location of the force application point and the amount of the moment applied to the four incisors were evaluated. As the bracket positioning plane was moved parallel toward the incisal edge, uncontrolled tipping and extrusion of the maxillary and the mandibular incisors were increased. But lingual tipping of the crown was decreased in the maxillary and the mandibular canines. As the bracket positioning plane was inclined toward the incisal edge, lingual tipping was increased in the 6 anterior teeth and extrusion of incisors and intrusion of the canine was also increased. As the retraction hook of the canine bracket was elongated, lingual tipping and extrusion of the central incisor and mesial movement and extrusion of the lateral incisor were increased. In the canine, mesial and labial movements of the crown were increased. When the moment was applied to the 4 incisors of the maxillary and the mandibular arch in the lingual central plane, 280 gf-mm in the maxillary central incisor, 500 gf-mm in the maxillary lateral incisor, 170 gf-mm in the mandibular central incisor and 370 gf-mm in the mandibular lateral incisor produced bodily movement of the individual tooth.

• The korean journal of orthodontics
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• v.28 no.4 s.69
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• pp.563-580
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• 1998

This study was designed to analysis the displacement and stress distribution of individual tooth by orthodontic force during distal on masse movement of the maxillary dentition. In this study, three dimensional finite element analysis was used. Author made the finite element model of maxillary teeth, periodontal ligament, alveolar bone and bracket with anatomic and physiologic characteristics on computer. Author analysed and evaluated the displacement and stress distribution of individual tooth when extraoral force, Class II intermaxillary elastics, ideal arch wire, MEAW and tip back bend were used for distal on masse movement of the maxillary dentition. These analyses were also applied in the case of the maxillary second molar were not extracted. Author compared the results of the cases which maxillary second molar were extracted or not. The results were expressed quantitatively and visually. Author obtained following results, 1. When anterior headgear was applied, the posterior translation, posterior tipping, and vertical displacement of teeth were produced more in the anterior segment of the dentition. 2. When Class II intermaxillary elastics were applied in the ideal arch wire, the teeth displacement were usually produced in the anterior segment. But when tip back bend were added in the ideal arch wire, the orthodontic force produced by elastics were transmitted to the posterior segment. As increasing the tip back bend, posterior translation and lingual tipping of anterior teeth were decreased, posterior translation and tipping displacement of posterior teeth were increased, and extrusion of anterior teeth by Class II elastics were decreased 3. When MDAW and Class II elastics were applied, the teeth movement were sir flu with the case of ideal arch wire and Class II elastics, but more small and uniform teeth displacement were produced Compared with the ideal arch wire, posterior tipping of the posterior segment were more produced than lingual tipping displacement of the anterior segment. 4. When the maxillary second molar without orthodontic appliance existed, the displacement of maxillary first molar were decreased.

• The korean journal of orthodontics
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• v.30 no.4 s.81
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• pp.377-386
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• 2000

At the finishing stage, the use of asymmetric elastics to treat mild skeletal and dental midline discrepancies often creates several side effects such as canted occlusal plane, tipped incisors and unesthetic results. This report presents the clinical cases with midline discrepancies, following a differential diagnosis, optimal mechanics, and considerations in treatment. Differential diagnosis and treatment mechanics with three-piece basal archwire can obtain predictable midline correction with minimal side effects.

• The korean journal of orthodontics
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• v.29 no.6 s.77
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• pp.699-706
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• 1999

Anchorage plays an important role in orthodontic treatment. Endosseous implants may be considered adequate firm anchorage. However, clinicians have hesitated to use endosseous implants as orthodontic anchorage because of limited implantation space, high cost, and long waiting period before osseointegration occurs. Recently, some clinicians have tried to use titanium miniscrews and microscrews in treatment due to their many advantages such as ease of insertion and removal, low cost, immediate loading, and the ability to place microscrews in any area of alveolar bone. The author treated a case with skeletal cortical anchorage using titanium microscrew implants. During six months of orthodontic force application from skeletal cortical anchorage, the author could get 4 mm bodily retraction and intrusion of upper anterior teeth. The most outstanding result was a 1.5 mm posterior refraction of the upper posterior teeth. The titanium microscrew implants had remained firm and stable throughout treatment. These results indicate that skeletal cortical anchorage might be a very good option.

• The korean journal of orthodontics
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• v.30 no.1 s.78
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• pp.9-17
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• 2000

This study was performed to compare and analyze the mode of tooth movement according to the timing of orthodontic force application alter extraction. The upper right and left third incisors were carefully extracted at three-week interval in lout adult dogs. Both canines were used as an anchorage for the bodily movement of the upper second incisors. Orthodontic forte of 100 gm was simultaneously applied at one week after extraction on one side and four weeks after extraction on the other side using NiTi closed coil spring. While orthodontic force was applied for twelve weeks, the amount of tooth movement was measured at every second week with digital calipers. The animals were sacrificed at twelve weeks and histologic examination was executed to reveal any difference between both sides. The results were obtained as follows. 1. The tooth movement was likely to be faster in lout-week side 4han one-week side for the first two weeks while faster in one-week side during next two weeks 2. The rate of tooth movement was fastest during four to six weeks period, then decreased gradually. 3. The total amount of tooth movement was likely to be larger in one-week side compared to four-week side. 4. Any damage to tooth and periodontal tissue could not be seen in the histologic section of one-week side. These results suggest that earlier application of orthodontic force is better than later after extraction In terms of the rate of tooth movement.

• 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.