• The korean journal of orthodontics
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• v.15 no.2
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• pp.163-174
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• 1985

The requirements of orthodontic wire should include chemical stability, non-discoloration and non-corrosion in oral environment. Ability to be soldered, ease of fabrication and elasticity should be also considered. The purpose of this study was to compare and analyze the physical properties of Tru-chrome wire and manufactured E.S.S. (Experimental Stainless Steel) wire similar to Tru-chrome. The results were as follows: 1. Tru-chrome wire and E.S.S. wire were SUS 304 which was 18 Cr-8Ni austenite stainless steel. There was not significant difference in each composition between two wires. 2. There were not significant differences in ultimate tensile strength, yield strength, elongation and modulus of elasticity between Tru-chrome and E.S.S. wires. 3. There was not significant difference between flexuree modulus of elasticity of Tru-chrome and E.S.S. wires. 4. Micro-hardness value of E.S.S. wire was more than that of Tru-chrome wire and they were softened significantly by solution heat reatment. 5. Micro-structure of Tru-chrome and E.S.S. wires showed fibrous interlocking grains, and an austenite structure after solution heat treatment. 6. There was significant difference between corrosion rate of Tru-chrome and E.S.S. wires.

• The korean journal of orthodontics
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• v.20 no.3 s.32
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• pp.593-608
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• 1990

Facial cleft is not a common anomaly of craniofacial region. But it is often accompanied with cleft lip and/or palate, so it seems important to orthodontist. Facial cleft is defined as a fissure or elongated opening of the facial region, and it's etiology is the failure of the fusion of the parts which will form the face in embryonic developmental period. Facial cleft can be classified according to the time of occurrence and the area involved during developmental period. It developes 1-2.5 weeks earlier than cleft lip and/or cleft palate. In facial cleft, the deformity is generally confined to the facial region, but sometimes deformity of other body region can accompany. The interaction of the facial cleft and the genetic anomaly is not confirmed, but genetic anomaly is known to be able to occur with the patient with other anomaly of body. As an orthodontist we should know the general considerations of facial cleft and it's treatment procedures other than orthodontic treatment.

• 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.36 no.6
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• pp.474-482
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• 2006

Self-ligating brackets have a permanently installed movable component to entrap the archwire which reduces much of the friction created by conventional ligation. Therefore, it allows for rapid tooth movement and shorter overall treatment time. Due to these advantages, interest in self-ligating brackets is increasing. In this report, several practical considerations for using self-ligating brackets are given to appreciate and maximize their benefits. It is thought that self-ligating brackets make shorter and more efficient treatment possible.

• The korean journal of orthodontics
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• v.24 no.2
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• pp.367-394
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• 1994

The purpose of this study was to evaluate self perception of occlusal status and recognition for orthodontic treatment as well as the prevalence of orthodontic treatment need objectively and subjectively. 3979 (male 2107, female 1872) school students of age 7~18 were analyzed by questionnaire and clinical examination and the results were as follows, 1. Perception of occlusal status on one's own was more generous than that of orthodontist's and it was affected by the factors such as age, patterns of malocclusion. 2. Recogniuon of subjective need for orthodontic treatment was more generous than that of objective need for the treatment, and factors such as age and sex of patient, parents' age and rate of education, income, occupation, classification of malocclusion and regional discrepancy were influenced. 3. Negative aspect of orthodontic treatment was influenced by the environmental factors. 4. A survey of want for orthodontic treatment showed one's alteration in recognition of the occlusal status with age and esthetic component was much more emphasized than functional component. 5. The multivariate discriminanat analysis for orthodontic treatment group showed that mother's rate of education, classification of malocclusion, demographic characteristics were critical in the determination of treatment group. 6. Test of inter-examiner reliability showed moderate coincidence.

• The korean journal of orthodontics
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• v.19 no.3
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• pp.35-48
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• 1989

1795 patients who visited orthodontic department from 1979 to 1987, were surveyed on the yearly tendency of patient distribution and state of Angle's classification. The results were as follows; 1. There was increased visiting rate of patient per year and higher visiting rate in female than in male. 2. 8-15 age group was 70.3% in total visiting patients and over 20 age group was 10.8%, under 7 age group was 7.3%. 3. Class I malocclusion was 26.3%, Class II div 1 was 31.0%, Class II div 2 was 1.6% and Class III was 41.1% in total visiting patient. 4. There was increased tendency to be received preventive treatment than fixed treatment and increased extracting rate per year in fixed treatment. 5. There was increased tendency for the number of the patient to be received orthognathic surgery.

• The korean journal of orthodontics
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• v.18 no.1 s.25
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• pp.155-163
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• 1988

The purpose of this study was to evaluate and compare frictional forces generated between orthodontic brackets and arch wires. Independent variables were chosen for study: arch wire size and shape, arch wire material, bracket width, and second-order angulation between bracket and arch wire. Kinetic frictional forces of stainless steel (0.014', 0.016', 0.018', 0.016' ${\times}$ 0.022', 0.018' ${\times}$ 0.022'), $\beta-titanium$ (0.016' ${\times}}$ 0.022') arch wires were measured on wide and junior edgewise twin brackets (0.018' ${\times}$ 0.022' slot). Instron was used to pull arch wires while $0^{\circ},\;3^{\circ},\;6^{\circ},\;or\;9^{\circ}$ angulation between and wire and bracket was given. The results were as follows: 1. The frictional force of $\beta-titanium$ wire was larger than that of stainless steel wire. 2. The frictional force was generally increased as the size of wire is increased. 3. The frictional force of rectangular wire was larger than that of round wire. 4. As second order angulation was increased, the frictional force was also increased. 5. The frictional force was larger on a wide bracket than on a junior bracket.

• The korean journal of orthodontics
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• v.18 no.1 s.25
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• pp.227-234
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• 1988

To study diagnosis and treatment plan of malocclusion, comparison of race and nation and consideration of treatment technique, 885 orthodontic patients of the department of orthodontics, Infirmary of dental college, Chosun University were evaluated. The frequency and pattern of tooth extraction were studied according to malocclusion types and developmental stages of occlusion and sex. Thefollowingresultswereobtained. 1. Average frequency of tooth extraction for orthodontic treatment was $38.3\%$. 2. The frequency of tooth extraction was $43.7\%$ in class I malocclusion, $34.2\%$ in class II malocclusion and $32.1\%$ in class III malocclusion. 3. The drequency of tooth extraction was the highest in permanent dentition $(49.2\%)$. 4. The frequency of tooth extraction was not different between male and female. 5. The frequency of 3-4 premolars extraction was the highest $(57.5\%)$ and that of lower incisor extraction was the lowest $(2.9\%)$ in patterns of tooth extraction. 6. Both frequency of unilateral and single arch extraction were the highest in class III malocclusion.

• The korean journal of orthodontics
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• v.35 no.2 s.109
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• pp.148-152
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• 2005

This case report describes the treatment of an impacted tooth in relation to pediatric mandibular fracture. A 10-rear-old girl presented with au impacted mandibular canine related with a miniplate in the left mandibular body area. An ordinary surgical traction ended in failure. Good occlusion was established by removal of the miniplate. It would be considered important to make an exact diagnosis of the cause and remove the mechanical obstruction instantly for successful orthodontic treatment of an impacted tooth.

• Proceedings of The Korean Cleft Lip And Palate Association
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• 1997.06a
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• pp.41-41
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• 1997