• The korean journal of orthodontics
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• v.41 no.6
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• pp.411-422
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• 2011

Objective: The aim of this study was to evaluate the lip and perioral soft tissue changes after bracket bonding. Methods: The soft tissue changes in 45 adult patients (age greater than 18 years and less than 29 years) without severe skeletal discrepancy were evaluated using three-dimensional images acquired with a laser scanner before and after bracket bonding was performed using 4 types of labial orthodontic brackets. Results: Among the statistically significant changes in distance observed for the landmarks, the biggest change was observed in forward movement. The landmarks on the lateral sides also showed significant changes. While the landmarks on the upper lip showed significant upward movement, those on the lower lip showed significant downward movement. However, the changes were smaller for the landmarks on the upper lip (average, 0.87 mm) than for the landmarks on the lower lip (average, 1.21 mm). The type of bracket used did not significantly affect the soft tissue changes. Conclusions: These findings will help predict soft tissue changes after bracket bonding for orthodontic treatment.

• Journal of the korean academy of Pediatric Dentistry
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• v.40 no.1
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• pp.41-47
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• 2013

Maxillary canines are the most commonly impacted or ectopically erupted teeth. If we find the abnormality of maxillary canines early, we can manage it reasonably and systematically. If we cannot see the spontaneous normalization at the periodic recall, primary canine extraction will be the next treatment choice. However, if the primary canine is extracted too early, the extraction socket will be filled with hard bone and then the eruption pathway can be locked. So it is more beneficial to extract the primary canine at the period about 6 months before the normal canine eruption time. The next treatment plan can be surgical and orthodontic approaches before the root apical closure of the impacted canine. Sometimes, surgical extraction and further prosthetic procedure can be needed for a severely malposed impacted canine or badly resorpted incisor. This is the case of the idiopathic mesial movement of impacted maxillary canines.

• Journal of the korean academy of Pediatric Dentistry
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• v.24 no.3
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• pp.597-601
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• 1997

This paper presents improper use of latex-elastic ring in movement of teeth and its consequence. Simple orthodontic movement of teeth including closure of diastema may be achieved by the use of simple method with fixed or removable appliance associated with latex-elastic ring. But, if it is used alone, it acts as a local irritant and then produces localized periodontitis. In case of localized periodontitis resulting from latex-elastic ring, diagnosis is difficult because the patient is usually unaware of the presence of the rings on the roots of the involved teeth and because the ring is not probed and is radiolucent and therefore not discernible radiographically and clinically. Occasionally, surgery is requred for the detection. This case emphasizes the necessity that the use of latex-elastic ring in closing diastema should be accompanied with removable or fixed appliance as well as close professional supervision. Its use without adequate provision for stabilization or retention on the crowns of teeth results in destruction of periodontal support and the teeth may be lost.

• The korean journal of orthodontics
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• v.21 no.3
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• pp.543-560
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• 1991

Practitioners are aware of the presence of friction between bracket system and archwire during sliding movement of teeth. Clinically a mesiodistally applied force must exceed the frictional force to produce a tooth movement. The objective of this study were to determine, on a dry condition, changes in magnitude of friction with respect to load, 3rd order inclination (Torque), archwire materials and ligature type. Three wire alloys (Stainless Steel, TMA, NiTi) in two wire sizes (.016, .016x, .022 inch) were examined respect to two bracket system (Straight, Standard), and two ligature type (Metal, Plastic ligature) at three levels of load (100g, 150g, 200g). The results were as follows; 1. Frictional resistance was found to increase with increasing load for S.S., TMA, NiTi. 2. The straight bracket system was exhibited more frictional force than standard bracket system for .016x, .022 S.S. tightly ligated metal ligature. But, torque difference did not increase friction for loose metal ligature & plastic ligature. 3. Regardless of the ligature type, torque and load, stainless steel wire sliding against stainless steel exhibited the lowest friction, and TMA sliding against stainless steel exhibited the highest friction. 4. The loose stainless steel ligature generated lower frictional resistance than plastic ligature in all experimental groups. 5. The following factors affected friction in decreasing order; wire material ligature type, and load.

• The korean journal of orthodontics
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• v.33 no.6 s.101
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• pp.465-474
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• 2003

The great variety of commercial brands of orthodontic wires available on the market, stimulated by the so called superior wires (nickel titanium with shape memory effect and superelastic nickel titanium), makes the professional choice for a suitable and less expensive material difficult. The in vitro study of the mechanical properties of the orthodontic wires acts as an auxiliary tool for the professional. In this paper, a comparative study of mechanical properties was made, using stress strain tests for 4 types of orthodontic wires (conventional stainless steel, multistranded steel, superelastic nickel titanium and thermoactivated nickel titanium) separated into 5 groups. A series of 6 tests were tested for each group of wires. Initially, each group was tested 3 times until the wires broke. Furthermore, 3 more tests for each group were performed, stretching the wires under standardized activation loads, for a reliable comparison of their mechanical properties, during loading and unloading. 1 tests were applied to check differences among the groups. In vitro, the results suggest that regarding the mechanical properties supposedly desirable for physiological teeth movement, such as resilience, elasticity modulus, strength liberated during unloading, and the way that strength is liberated, thermoactivated nickel titanium wires, acting under mouth temperature, seems to be a good choice, fellowed by superelastic nickel titanium, multistranded stainless steel, and conventional stainless sleet. Superelasticity was demonstrated for superelastic nickel titanium wires. When at $37^{\circ}C$, thermoactivated nickel titanium wires showed shape memory effect, showing that temperature is important for enhancing the mechanical properties.

• The korean journal of orthodontics
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• v.27 no.6 s.65
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• pp.943-954
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• 1997

Forces needed for orthodontic tooth movement are obtained from various appliances such as orthodontic wires or elastic rubber. Orthodontic elastic rubber is widely used clinically, but permanent deformation and force decay may occur from the environmental changes, time of clinical use and the extent of the stretch, making the Prediction of force being applied difficult. The Present study examined and compared the changes in residual force between three brands of elastomeric chains (Ormco Generation II Power Chains ; brand A, RMO : Energy-Chain ; brand B, Unitek : AlastiK ; brand C) under various environmental conditions, amount of initial force, types of elastomer and the rate of extension. The characteristic physical properies of the elastomeric chains were as follows. 1. In all three brands, the residual force ratio was largest when the chains were stored in air, with no difference between water and saliva. 2. In all three brands, after 24 hours, there was no statistical difference in residual force ratio according to the initial force level. 3. In Brand A and B, the presence of filament had no correlation with the residual force ratio. In Brand C force decay was more severe when the chain contained filament. 4. In each brand, rate of extension had no effect on residual force ratio. 5. Brand B showed relatively higher residual force ratio compared to other brands.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.3
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• pp.506-512
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• 2007

Traumatic injury of tooth in children is commonly occurred problem. It is classified into tooth, periodontal tissue, supporting bone, soft tissue injury by it's area and extent. Among the periodontal tissue injuries, traumatically intruded teeth are common in anterior maxillary area, though the occurrence rate is rather low, the pulp and supporting tissue injury is possible by vertical impact. The treatment method of traumatically intruded teeth is various. Observation on the spontaneous reeruption for 3-4 weeks is recommended if the traumatized teeth are deciduous teeth or slightly intruded immature permanent anterior teeth. If this did not occur because the extent of intrusion is severe or the traumatized teeth are mature permanent anterior teeth, orthodontic traction is applied by fixed/removable appliances. At this time, light and continuous force is applied for the extrusive movement of the intruded teeth. When above procedures are impossible, surgical repositioning and fixation is recommended. In these cases, we performed conventional endodontic therapy for pulp necrosis and orthodontic traction with fixed appliance. We obtained satisfactory results and will report that.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.1
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• pp.26-32
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• 2005

A tooth impaction means a state that a tooth does not erupt out of oral mucosa or alveolar bone for many reasons. The reasons for an impaction of the Maxillary central incisor are an odontoma, supernumerary tooth, space loss, prolonged remaining or early loss of a preceding deciduous tooth, abnormalities of crown or root caused by trauma of a deciduous tooth and an ectopic position of a tooth germ. In the case of the impacted maxillary incisor, a rapid mesial movement of a lateral incisor leads a space loss and a midline deviation can be happened. Furthermore, it can cause a cyst. When we treated a patient with an impacted central incisor early, we could see a better prognosis. It means an early diagnosis and an exact treatment are very important. Generally if the impaction is not severe or it is caused by a keratinized covering tissue, a surgical exposure can induce an eruption easily but an orthodontic force is recommended when an eruption does not happen after a surgical method, when the eruption path is too transpositioned to be corrected spontaneously and when an impacted tooth is located so deeply. In the treatment using an orthodontic force, careful considerations about a root length, pulp, and a periodontal tissue can improve the periodontal and esthetic prognosis for the long follow-up results. This case is using an orthodontic traction following a periodic observation and in no expectation of spontaneous eruption. After treatment of this case, I have got some knowledges, so I report this case.

• The korean journal of orthodontics
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• v.30 no.6 s.83
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• pp.677-685
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• 2000

Anchorage plays an important role in orthodontic treatment. Because of limited anchorage Potential and acceptance problems of intra- or extraoral anchorage aids, endosseous implants have been suggested and used. However, clinicians have hesitated to use endosseous implants as orthodontic anchorage because of limited implantation space, high cost, and long waiting period for osseointegration. Titanium miniscrews and microscrews were introduced as orthodontic anchorage due to their many advantages such as ease of insertion and removal, low cost, immediate loading, and their ability to be placed in any area of the alveolar bone. In this study, a skeletal Class II Patient was treated with sliding mechanics using M.I.A.(micro-implant anchorage). The maxillary micro-implants provide anchorage for retraction of the upper anterior teeth. The mandibular micro-implants induced uprighting and intrusion of the lower molars. The upward and forward movement of the chin followed. This resulted in an increase of the SNB angle, and a decrease of the ANB angle. The micro-implants remained firm and stable throughout treatment. This new approach to the treatment of skeletal Class II malocclusion has the following characteristics . Independent of Patient cooperation. . Shorter treatment time due to the simultaneous retraction of the six anterior teeth . Early change of facial Profile motivating greater cooperation from patients These results indicate that the M.I.A. can be used as anchorage for orthodontic treatment. The use of M.I.A. with sliding mechanics in the treatment of skeletal Class II malocclusion increases the treatment simplicity and efficiency.

• The korean journal of orthodontics
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• v.27 no.4 s.63
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• pp.585-597
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• 1997

The purpose of this study was to evaluate the effect of estrogen on the periodontium and alveolar bone tissue response during experimental tooth movement in ovariectomized rats. Eighty female rats, 250gm in body weight, were classified into four groups ; sham operated group(NN), ovariectomized group(ON), ovariectomized & estrogen injected group(OE), sham operated & estrogen injected group(NE). flats were ovariectomized before 3 weeks to begin the experiment, which resulted in estrogen-deficient osteoporosis. In OE group & NE group, estrogen was injected $50{\mu}g/kg\;B.W.$ every other days. The left maxillary 1st molar was moved mesially with 60g force. Each foot rats were sacrificed after 1, 3, 7, 15 days from application of orthodontic appliance and alter additional 7 days from removal of orthodontic appliance. Histological findings on mesial roots of upper 1st molar in pressure and tension side are observed. The results were summarized as follows ; 1. In pressure side of alveolar bone, the number of osteoclasts and Howship's lacuna of ON group was significantly more than that of NN group from 1 day to 15 days(P<0.05). Especially the number of Howship's lacuna of ON group was significantly more than that of OE group during all experimental period(P<0.05). 2. In tension side of alveolar tune, the number of osteoclasts of ON group was significantly increased from 1 day to 3 days and decreased after 7 days. But the number of osteoclast of ON group was significantly mote than that of NN group during all experimental period(P<0.05). Also the number of Howship's lacuna of all groups was abruptly increased at 1 day, but slowly decreased till experimental 15 days. And the number of Howship's lacuna of of group was significantly more than that of NN group from 0 hr to 7 days(P<0.05). 3. The speed of tooth movement of OE group & NE group was similar to that of NN group(P>0.05). The amount of tooth movement of ON group between 7 days and 15 days was significantly greater than those of other groups(P<0.05). 4. The degree of relapse of ON group after 7 days from removal of orthodontic appliance was similar to those of other groups(P>0.05).