• The korean journal of orthodontics
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• v.18 no.1 s.25
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• pp.105-112
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• 1988

To predict duration of orthodontic treatment of malocclusion, 304 male and female patients whose orthodontic treatment was finished in department of orthodontics, Infirmary of dental college, Chosun University were studied. The duration of treatment was studied according to types of malocclusion, beginning ages of treatment, Hellman's dental ages, the determination of tooth extraction, types of tooth extraction and types of orthodontic appliance. The following results were obtained. 1. The duration of treatment was 18 months in Class I malocclusion, 20 months in Class II malocclusion and 24 months in Class III malocclusion. 2. The more early treatment was done, the more duration of treatment was needed according to beginning age of treatment and Hellman's dental ages. 3. Treatment of tooth extraction case was needed for 78 days more than that of non-extraction case. 4. The duration of treatment with unilateral extraction of premolars was the shortest (598 days) and that with single arch extraction of premolars was the longest (685 days) according to types of tooth extraction. 5. The duration of treatment by removable appliance was the shortest (237 days) and the combination of removable appliance, headgear and full banded appliance was the longest (1425 days) according to types of orthodontic appliance. 6. The duration of treatment was 18 months in typical orthodontic treatment with 4 extraction of premolar and full banded appliance.

• The korean journal of orthodontics
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• v.20 no.1
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• pp.183-195
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• 1990

The purposes of present study were to identify possible relationships between post-treatment changes and post-retention changes. The patient's models were composed of 58 samples, and were classified non-extraction group (30 samples) and extraction group (28 samples). For each sample the first models were taken prior to the start of treatment, the second models just after the end of treatment, and the third models two years after. The results were as follows: 1. In the cases of non-extraction group, increases were in intermolar width of maxilla, interbicuspid width of maxilla and arch perimeter of mandible during treatment period, but decreases were in the same measurements during post-retention period. 2. In the cases of extraction group, decreases were in intermolar width of mandible, interbicuspid widths of maxilla and mandible, arch length of mandible, arch perimeters of maxilla and mandible during treatment period. 3. Significant decreases were in the irregularity index of both extraction and non-extraction group during treatment period. 4. There were significant differences of arch dimensional changes in intermolar widths of maxilla and mandible, interbicuspid widths of maxilla and mandible, arch lengths of maxilla and mandible, arch perimeters of maxilla and mandible between non-extraction and extraction group.

• The korean journal of orthodontics
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• v.17 no.2
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• pp.235-246
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• 1987

The purpose of this study was to detect out the changes occured during orthodontic treatment. The sample was consisted of 77 orthodontic patients. For this study 13 linear lengths and arch area were measured in maxilla, mandible respectively and were analyzed statistically. The results were as follows 1 The sequence of changes in the form and dimensions of dental arches following orthodontic treatment was as follows Class I malocclusion, Class III malocclusion, Class II malocclusion. 2 Changes in the form and dimensions of dental arches were greater in extraction cases than those of non-extraction cases 3 In comparison with maxilla and mandible on the amount of changes following orthodontic treatment in each malocclusion group, significant differences were greatest in class III malocclusion 4 In comparison with maxilla and mandible on the amount of changes following orthodontic treatment in extraction and non-extraction cases, significant differences were greater in extraction cases than those of non-extraction cases 5. The amount of changes during orthodontic treatment in extraction and non-extraction cases in male was not different from female's.

• The Journal of the Korean dental association
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• v.57 no.6
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• pp.326-332
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• 2019

Extraction treatment has been used for a long time to treat crowding or lip protrusion patients and still extraction decision is the most difficult and important decision during diagnosis and treatment planning. If the amount of crowidng is severe, premolar extraction is often considered. Because of their location, premolar extractions would seem to allow for the most straightforward relief of crowding and the improvement of soft tissue profile. But patients and their parents often prefer nonextraction approach if possible and such a preference gives us serious question about the boundary of nonextraction treatment. Because Orthodontic Mini-Implant (OMI) become popular these days, distalization of posterior teeth can be obtained easily without patient's compliance. For this reason, many orthodontists are trying to treat crowding patient with nonextraction than before. But sometime, unexpected side effects are observed including unesthetic profile, impaction of second molar and long treatment time. All the tools for space gaining - extraction, arch expansion, molar distalization and interproximal enamel reduction - have their limitations and indications. Possible side effects and limitations should be carefully considered during the treatment planning. Although Korean patients usually require extraction more often than US or European patients, more knowledge about the tools for space gaining would help us to decrease the rate of extraction and the problems during treatment of crowding patients.

• The korean journal of orthodontics
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• v.23 no.1 s.40
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• pp.123-136
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• 1993

The purpose of this report is to present the successful improvement of occlusal relationship and facial esthetics in class II division 1 malocclusion with severe labioversion of upper anterior teeth and severe overjet, and in class II malocclusion with infraversion of bilateral maxillary canines by MEAW mechanics, which enables us to get effective distal on mass movement of maxillary dentition, with upper second molar extraction. After treatment, there were natural contact points at canine and premolar regions, normal occlusal relation-ship and treatment results, satisfied the gnathologic concept, in this 2 cases. Compared with the routine treatment with premolar extraction, the treatment time and patients' discomfort were reduced. And the MEAW mechanics, which enables us to get effective distal on mass movement of maxillary dentition, resulted in reduction of the treatment time and getting the good treatment results. Consequently, the majot concerns in orthodontic treatment are appropriate diagnosis and treatment plan, so, the application of second molar extraction with appropriate case analysis and diagnosis is very helpful to orthodontic treatment.

• 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.

• Journal of Korean Society of Water and Wastewater
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• v.12 no.3
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• pp.30-40
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• 1998

Increasing water consumption produced sludge problems of the water treatment plants. The objective of this study is to investigate aluminium coagulants recovery n acidic and alkaline conditions. Water treatment plant sludge produced in Pusan Metropolitan City were tested for the aluminium extraction process. Experiment samples were obtained in summer from water treatment plants of Deoksan and Myongjang. Aluminium coagulants used in these plants during the test period were polyaluminium chloride(PAC), polyaluminium sulfate organic(PSO), polyaluminium sulfate silicate(PASS). Aluminium contents of water treatment sludge were in the range of 7.2~10.9% of the total solids. The recovery percentages for aluminium and iron by acidic extraction method was evaluated to 88% and 42% respectively. Extracted mass variation for other materials such as iron, manganese, total organic carbon was observed during the extraction operation. Alkaline extraction produced more than two times amount of total organic carbon than that in the acidic extraction process.

• Food Science and Preservation
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• v.12 no.2
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• pp.130-134
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• 2005

This study was conducted to investigate the effects of pretreatment and extraction methods on the water extraction yields of sugar, protein and phenolic compounds, and the antioxidative activity of extract from Ganoderma lucidum. The herb was ground, sifted, and treated for 10 min with microwave (2,450 MHz) and ultrasound (20 kHz), and then extracted by boiling underatmospheric pressure and pressured boiling. Particle size $(0.8\~2.4\;mm)$, extraction time (2 hr) and solvent/solid ratio (20:1) were selected as optimal conditions for extraction.. Microwave and ultrasound treatment increased the extraction yields of total sugar, protein and phenolic compounds and the radical scavenging activity of extract. In comparison with microwave treatment and ultrasound treatment, microwave treatment was more effective than that of ultrasound treatment. The yields of all three compounds and the radical scavenging activity of extract were higher in pressured boiling extraction than in boiling underatmospheric pressure. The results showed that microwave radiation and sonication prior to extraction, and pressured extraction could be utilized for improving the extraction efficiency of G. lucidum.

• The korean journal of orthodontics
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• v.48 no.3
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• pp.172-181
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• 2018

Objective: This study was performed to investigate buccal facial depth (BFD) changes after extraction and nonextraction orthodontic treatments in post-adolescent and adult female patients, and to explore possible influencing factors. Methods: Twelve and nine female patients were enrolled in the extraction and nonextraction groups, respectively. Changes in BFD in the defined buccal region and six transverse and two coronal measuring planes were measured after registering pretreatment and posttreatment three-dimensional facial scans. Changes in posterior dentoalveolar arch widths were also measured. Treatment duration, changes in body mass index (BMI), and cephalometric variables were compared between the groups. Results: BFD in the buccal region decreased by approximately 1.45 mm in the extraction group, but no significant change was observed in the nonextraction group. In the extraction group, the decrease in BFD was identical between the two coronal measuring planes, whereas this differed among the six transverse measuring planes. Posterior dentoalveolar arch widths decreased in the extraction group, whereas these increased at the second premolar level in the nonextraction group. The treatment duration of the extraction group was twice that of the nonextraction group. No differences were found in BMI and Frankfort horizontal-mandibular plane angle changes between the groups. BFD changes in the buccal region moderately correlated with treatment duration and dental arch width change. Conclusions: BFD decreased in adult female patients undergoing extraction, and this may be influenced by the long treatment duration and constriction of dentoalveolar arch width. However, nonextraction treatment did not significantly alter BFD.

• The korean journal of orthodontics
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• v.49 no.4
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• pp.222-234
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• 2019

Objective: To investigate the three-dimensional lip vermilion changes after extraction and non-extraction orthodontic treatment in female adult patients and explore the correlation between lip vermilion changes and incisor changes. Methods: Forty-seven young female adult patients were enrolled in this study (skeletal Class III patients were excluded), including 34 lip-protruding patients treated by extraction of four first premolars (18 patients requiring mini-implants for maximum anchorage control and 16 patients without mini-implants) and 13 patients requiring non-extraction treatment. Nine angles, seven distances, and the surface area of the lip vermilion were measured by using pre- and post-treatment three-dimensional facial scans. Linear and angular measurements of incisors were performed on lateral cephalograms. Results: There were no significant changes in the vermilion measurements in the non-extraction group. The vermilion angle, vermilion height, central bow angle, height/width ratio, and vermilion surface area decreased significantly after the orthodontic treatment in the extraction groups, but the upper/lower vermilion proportion remained unchanged. Significant correlations were found between the changes in incisor position and those in vermilion angles, vermilion height, and surface area. Conclusions: Extraction of the four first premolars probably produced an aesthetic improvement in lip vermilion morphology. However, the upper/lower vermilion proportion remained unchanged. The variations in the vermilion were closely related to incisor changes, especially the upper incisor inclination changes.