• The korean journal of orthodontics
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• v.29 no.4 s.75
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• pp.457-466
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• 1999

It has been reported that skeletal relapse and dental change after mandibular setback do occur not only after intermaxillary fixation(IMF) removal but also during IMF The side effects of skeletal relapse during IMF have clinical importance because they can cause many Postoperative orthodontic Problems. Generally, the Prevention of solid union between segments, compensatory tooth movement, anterior openbite, etc. have been cited as the side effects of jaw displacement. The purpose of this study was to evaluate the skeletal relapse and dental change during IMF. The material consisted of 28 patients who were treated by BSSRO(bilateral sagittal split ramus osteotomy), wire osteosynthesis, IMF for correction of mandibular prognathism. Through cephalometric analysis, the amount and direction of surgical movement, skeletal relapse and dental change during IMF were measured. The correlation between surgical movement and skeletal relapse, between skeletal relapse and dental changes were evaluated. The following conclusions were obtained; 1. Distal segment was repositioned backward and upward, proximal segment showed clockwise rotation during surgery. 2. During ]m, anterior portion of distal segment was displaced backward and posterior portion was displaced upward. Proximal segment was displaced upward with forward movement of p-Go(gonion of proximal segment). Backward surgical movement of p-GO was significantly correlated with forward displacement of p-Go. 3. Overjet and overbite were not changed during IMF. The compensatory tooth movements during IMF were characterized by retroclination of upper incisors md retroclination, extrusion of lower incisors. These compensatory tooth movements had statistically significant correlation with upward displacement of d-Go (gonion of distal segment).

• 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 the korean academy of Pediatric Dentistry
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• v.26 no.1
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• pp.38-43
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• 1999

Tooth transposition is the phenomenon in which two teeth in the dental arch are exchanged. The tooth most frequently involved in transposition is the permanent maxillary canine, especially with the first premolar. The etiology of transposition is still an enigma. Interchange of tooth germs, migration during eruption, genetic factor, local pathologic factors may be suggested as possible etiologic factors. There are three main options for treatment, which are the extraction of one of the transposed teeth, the alignment in the transposed position, the orthodontic movement of the teeth to their correct positions. If complete transposition occurred especially in mandible, alignment of teeth in the transposed position followed by occlusal reduction and esthetic restoration is usually recommended. The presented two-case report will describe the maxillary canine to the first premolar and to lateral incisor transposition with associated peg lateralis and retained primary canines. Although alignment the transposed teeth in original position is ideal treatment, it companies many complication as root resorption, alveolar bone destruction, gingival deheisence, etc. Therefore the treatment procedures in these case was relative cost-benefit effective method to both clinician and patients.

• Journal of the korean academy of Pediatric Dentistry
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• v.26 no.1
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• pp.146-150
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• 1999

With the improved cure rates for childhood malignant conditions in the past decade, late effects of cancer therapy must be recognized to minimize their impact on the quality of life in long-term survivors. Chemoradiation therapy is a major part of pediatric oncology treatment and is implicated in causing tooth agenesis, microdontia, root shortening, early apical closure, and coronal hypocalcification. Dental development may be affected by illness, trauma, chemotherapy, or radiation therapy at any point prior to complete maturation. Treatment given during the first 3.5 years of life was more likely to affect the dental lamina and crown formation and result in a small tooth. Dental treatment affected by chemoradiation damage to developing teeth includes orthodontic tooth movement, prosthetic abutment consideration, periodontal health, space maintenance, requirement for home fluoride regimens to protect hypomineralized teeth, and enodontic procedures. Dental abnormalities are common in patients treated for cancer, and these children require aggressive dental follow-up. Meticulous surveillance may facilitate detection of abnormalities, enabling the dental practitioner to intervene earlier in promoting a more aggressive regimen of oral care, thus reducing the morbidity associated with dental sequelae of oncotherapy, specifically periodontal disease and malocclusion. In this case, we report microdontia of all permanent second premolar and second molar in an 8 year old boy treated with chemotherapeutic agents during period of active dental development(14 months to 38 months of age).

• The korean journal of orthodontics
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• v.13 no.2
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• pp.177-183
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• 1983

The soft tissue covering of the face plays an important role in facial esthetics, speech and other physiologic functions. Thus, it is recognised by all clinical orthodontists that success of orthodontic treatment is closely related to the changes in soft tissues of the face. The purpose of this study was to evaluate the changes of bony and soft tissues in prepost treatment of Angle's Class III malocclusion. The sample consisted of 18 males and 37 females, pretreatment age of 9 years to 11 years. For this study 11 landmarks were plotted, 14 linear length, 4 soft tissue thickness and 2 angles were measured. The obtained results were as follows; 1. In the linear measurements of bony and soft tissue changes, A, Is, Ss, Ls and Li were located more anteriorly in both sexes. However Si and B showed more remarkable anterior movement in female. 2. In the comparison of the changes of the soft tissue thickness, Ss and Li in male subjects and Ss in female subjects increased. 3. In the degree of correlation between changes in the soft tissue profile and changes in the skeletal profile, Is: Ls, Il: Li and B: Si in both sexes had significant correlations. However A:Ss had remarkable significant correlation in female. 4. There were significant correlations between change in ${\angle}A$ and change in ${\angle}B$ in all sexes. 5. There were little correlation between changes in distance difference of Is and Ii and Change in distance difference of Ls and Li in all sexes.

• The korean journal of orthodontics
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• v.19 no.1 s.27
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• pp.245-256
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• 1989

Translational movement along an arch wire requires sufficient force to overcome frictional forces between bracket and arch wire. The orthodontist must appreciate the importance of friction in this process, and study out the influencing factors on the level of friction. The purpose of this study was to evaluate the effect of artificial saliva on frictional resistances generated between the bracket and arch wire. Independent variables of this study were arch wire material, angulation and environment. Static frictional forces of cobalt-chromium, heat-treated cobalt-chromium, beta-titanium, stainless steel wires were measured under non-angulated dry, angulated dry, non-angulated saliva, angulated saliva conditions. The results were as follows: 1. Stainless steel wires showed lower friction values in non-angulated dry condition, and heat-treated cobalt-chromium wires showed higher friction values in angulated dry condition. Higher friction values were showed in order of cobalt-chromium. stainless steel, heat-treated cobalt-chromium and beta-titanium wires in non-angulated saliva condition. and were showed in order of stainless steel, cobalt-chromium, heat-treated cobalt-chromium, beta-titanium wires in angulated saliva condition. 2. Angulation increased friction for stainless steel wires under dry condition. 3. Artificial saliva decreased friction for cobalt-chromium wires and increased friction for stainless steel wires under non-angulated condition. 4. Artificial saliva decreased friction for all wires except beta-titanium wires under angulated condition. 5. Regardless of angulation or environment. heat-treated cobalt-chromium and beta-titanium wires showed higher friction values, and stainless steel wires showed lower friction values.

• The korean journal of orthodontics
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• v.48 no.4
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• pp.236-244
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• 2018

Objective: The aim of this study is to compare the adaptation of a straight wire between brackets positioned at the mid-lingual surface and those placed gingivally by using a three-dimensional simulation software. Methods: This cross-sectional study was performed using OrthoAid, an in-house software. The subjects were 36 adolescents with normal Class I occlusion. For each dental cast, two bracket positioning approaches, namely the middle and gingival, were examined. In the middle group, the reference points were placed on the mid-lingual surface of each tooth, while in the gingival group, the reference points were positioned lingually on the anterior teeth. A 4th degree polynomial was adopted, and the in-plane and off-plane root mean squares (RMSs) of the distances between the reference points and the fitted polynomial curve were calculated using the software. Statistical analysis was performed using the paired-samples t-test (${\alpha}=0.05$). Results: The mean in-plane RMS of the polynomial curve to the bracket distance in the gingival group was significantly lower than that in the middle group (p < 0.001). The off-plane RMS was higher in the gingivally positioned brackets in the maxilla than in the middle group (p < 0.001). However, the off-plane RMS in mandible was not statistically significantly different between the two groups (p = 0.274). Conclusions: The results demonstrated that the gingival placement of lingual brackets on the anterior teeth could decrease the distance between a tooth and the straight wire.

• The korean journal of orthodontics
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• v.40 no.1
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• pp.50-60
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• 2010

The purpose of this article was to evaluate the effects of a new upper molar distalization system, the Frog Appliance, on dentofacial structures in a Class II, division 1 patient. An 11-year-old girl was referred to our clinic for orthodontic treatment. She had a mild skeletal Class II malocclusion with Class II molar and canine relationship on both sides. The treatment plan included distalization of the upper first molars bilaterally followed by full fixed appliance therapy. For the upper molar distalization, a new system, the Frog Appliance, was constructed and applied. Lateral cephalometric radiographs were used to evaluate the treatment results. Distalization of the upper first molars was achieved in four months successfully, and Class I molar relationship was obtained. Total treatment time was 16 months. According to the results of the cephalometric evaluation, a nearly bodily distal molar movement with a slight anchorage loss was attained. In conclusion, the Frog Appliance was found to be a simple, ef ective, non-invasive, and compliance-free intraoral distalization appliance for achieving bilateral molar distalization.

• The korean journal of orthodontics
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• v.46 no.6
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• pp.379-385
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• 2016

Objective: Forced eruption has been proposed for the reconstruction of deficient bone and soft tissue. The aim of this study was to examine the changes in the alveolar ridge width and the vertical levels of the interproximal bone and papilla following forced eruption. Methods: Patients whose hopeless maxillary anterior teeth were expected to undergo severe bone resorption and soft tissue recession upon extraction were recruited. In addition, patients whose maxillary anterior teeth required forced eruption for restoration due to tooth fracture or dental caries were included. Before and after forced eruption, the interproximal bone height was measured by radiographic analysis, and changes in the alveolar ridge width and the interproximal papilla height were measured with an acrylic stent. Results: This prospective study demonstrated that the levels of the interproximal alveolar bone and papilla were significantly increased by 1.36 mm and 1.09 mm, respectively, in the vertical direction. However, the alveolar ridge width was significantly reduced by an average of 0.67 mm in the buccolingual direction. The changes in the level of the interproximal alveolar bone and papilla were positively correlated. Conclusions: Although the levels of the interproximal bone and papilla were significantly increased, the alveolar ridge width was significantly decreased following forced eruption. There was a modest positive and significant correlation between the changes in the height of the interproximal alveolar bone and the papilla. Based on our findings, modification of vertical forced eruption should be considered when augmentation of the alveolar ridge width is required.

• The korean journal of orthodontics
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• v.23 no.3 s.42
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• pp.375-389
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• 1993

The delivery of optimal orthodontic treatment is greatly influenced by a clinician's ability to predict and control tooth movement achieved by applying known force systems to the dentition. It is important to determine the location of the center of resistance of a tooth or group of teeth to better understand the nature of their displacement characteristics under the various force levels. The purpose of this study was to define the location of the centers of resistance of various units of the upper anterior segment for lingually directed 100gm and 200gm force in a dry human skull. The units investigated were composed of four incisors and six anterior teeth. In addition, the effect of change in force magnitude on the location of the center of resistance of these units was investigated. The laser reflection technique was used to measure the initial displacements of the consolidated teeth under loading. The results were as follows: 1. The instantaneous center of resistance for the four anterior teeth was located vertically between level 4 and level 5-that is, at $37.4\%$ apical to the cementoenamel junction level. 2. The instantaneous center of resistance for the six anterior teeth was located vertically just beneath level 5-that is, at $50.3\%$ apical to the cementoenamel junction level. 3. Increasing force levels had little effect on the location of the center of resistance of a given unit. 4. The location of the instantaneous center of resistance shifted apically as the number of dental units consolidated increased.