• Maxillofacial Plastic and Reconstructive Surgery
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• v.28 no.4
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• pp.320-328
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• 2006

Purpose: The aim of this study was to evaluate the effects of pterygomaxillary separation on dimensional changes of dental arch following surgically-assisted rapid maxillary expansion (SARME). Patients and Methods: Eighteen adults who had been treated by SARME for transverse maxillary deficiency from May 2000 to August 2005 were evaluated. Thirteen patients (Group 1) were treated with subtotal Le Fort I osteotomy including pterygomaxillary separation and anterior midpalatal osteotomy. The same operation was performed in five patients (Group 2) except pterygomaxillary separation. Dental study casts were taken before operation and after removal of expansion device. And then, skeletal and dental parameters were measured pre- and post-operatively. Results: 1. Changes of mean interdental width 1) In group 1, mean maxillary interdental width was increased 70%($47{\sim}99%$), 95%($84{\sim}115%$), and 77%($57{\sim}94%$) of total expansion on canine, first premolar, and first molar region, respectively after retention. 2) In group 2, mean maxillary interdental width was increased 77%($59{\sim}100%$), 78%($45{\sim}107%$), and 86%($57{\sim}116%$) of total expansion on canine, first premolar, and first molar region, respectively after retention. 3) There was a statistical difference between the change of interdental width of group 1 and group 2 at first premolar(p<0.05). 2. Changes of mean interalveolar width 1) In group 1, mean maxillary alveolar bone width was increased 66%($42{\sim}84%$), 74%($42{\sim}104%$), and 57%($31{\sim}78%$) of total expansion on canine, first premolar, and first molar region, respectively after retention. 2) In Group 2, mean maxillary alveolar bone width was increased 73%($55{\sim}98%$), 67%($36{\sim}89%$), and 59%($48{\sim}73%$) of total expansion on canine, first premolar, and first molar region, respectively after retention. 3) There were no statistical differences between group 1 and group 2 at each teeth area. Conclusion: These results suggest that SARME without pterygomaxillary separation may allow the relatively equal expansion at both anterior and posterior teeth area and most amounts of maxillary interdental expansions were acquired with the expansion of the maxilla by SARME.

• The korean journal of orthodontics
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• v.31 no.1 s.84
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• pp.25-38
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• 2001

The purpose of this study was to compare the force, the displacement and the stress distribution on the maxillary first molars altered by the application of various asymmetric head-gear. For this study, the finite element models of unilateral Cl II maxillary dental arch was made. Also, the finite element models of asymmetric face-bow was made. Three types of asymmetric face-bow were made : each of the right side 15mm, 25mm and 35mm shorter than the left side. We compared the forces, the displacement and the distribution of stress that were generated by application of various asymmetric head-gear, The results were as follows. 1. The total forces that both maxillary first molars received were similar in all groups. But the forces that mesially positioned tooth received were increased as the length of the outer-bow shortened, and the forces that normally positioned tooth received were decreased as the length of the outer-bow shortened. 2. In lateral force comparison, the buccal forces that normally positioned tooth received were increased as the length of the outer-bow shortened, and the buccal fortes that mesially positioned tooth received were decreased as the length of the outer-bow shortened. Though the net lateral force moved to the buccal side of normally positioned tooth as the length of the outer-bow shortened, both maxillary first molars received the buccal force. That showed 'Avchiai Expansion Effect' 3. The distal forces, the extrusion forces and the magnitudes of the crown distal tipping that mesially positioned tooth received were increased as the length of the outer-bow shortened, and the forces that normally positioned tooth received were decreased as the length of the outer-bow was shortened. 4. The magnitude of the distal-in rotation that normally positioned tooth received were increased as the length of the outer-bow was shortened. But, mesially positioned tooth show two different results. For the outer-bow 15mm shortened, mesially positioned tooth showed the distal-in rotation, hut for the outer-bow 25mm and 35mn shortened, mesially positioned tooth showed the distal-out rotation. Thus, the turning point exists between 15mm and 25mm. 5. This study of the initial stress distribution of the periodontal ligament at slightly inferior of the furcation area revealed that the compressive stress in the distobuccal root of the normally positioned tooth moved from the palatal side to the distal side and the buccal side successively as the length of the outer-bow shortened. 6. This study of the initial stress distribution of the periodontal ligament at slightly inferior of the furcation area revealed that the magnitudes of stress were altered but the total stress distributions were not altered in the mesiobuccal root and the palatal root of normally positioned tooth, and also three roots of mesially positioned tooth as the length of the outer-bow shortened.

• The korean journal of orthodontics
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• v.26 no.4
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• pp.325-340
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• 1996

Along with traditional goal of 'straightening teeth', today's orthodontics put more and more emphasis on facial esthetics. Naturally, the importance of soft tissue, which dictates one's facial form, is noticed. There have been many cephalometric studies on growth of hard tissue ; however, only a few on that of soft tissue. In Korea, various methods of sampling, measuring and analysing were used to study soft tissue changes, and yet, soft tissue changes along with process of normal growth have not been studied. The author carried out this study as a part of semi-longitudinal study on craniofacial growth and development of Korean children from ages of six to seventeen. 409 boys and 436 girls who'd had no systemic disease for the last three years and shown normal developmental and occlusal status were chosen as subjects. Cephalometric X-rays were taken of each subject, and facial form, lip position & form, nose form, and lip thickness were measured. Mean values and standard deviations were calculated according to age and gender, and figures and tables were drawn accordingly. The following results were obtained: 1. In respect to facial form, boys showed growth for longer period compared to girls. Also, lower face showed higher growth rate than upper face. 2. There was not much change in thickness of upper and lower lips with age; however, they appeared more prominent compared to caucasian children. 3. Nose grew horizontally with age. 4. Horizontal thickness of lower face increased with age, and upper lip thickness at nose base[A-Sn(FH)] showed more growth than anywhere else.

• The korean journal of orthodontics
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• v.27 no.4 s.63
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• pp.549-557
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• 1997

This study was designed to investigate the attrition pattern in Angle Class III malocclusion with facial asymmetry. The sample consisted of three groups, the 20 subjects of normal occlusion group(Group I), the 12 subjects of class III malocclusion without facial asymmetry group(Group II) and 17 subjects of Class III malocclusion with facial asymmetry group(Group III). Attrition areas from canine to second molar on both sides in upper and lower arch, totally twenty, was marked by pencil and mesured by computer system(INTERGRAPH CO. USA) 2 times and the average value was used for date processing. Attrition areas from canine to second molar on both sides in upper and lower arch, totally twenty, was marked by pencil and mesured by computer system(INTERGRAPH CO. USA) 2 times and the average value was used for date Processing. All attrition areas were measured 2 times and the average value was used for data processing The data were statistically analyzed by SAS program. The results of this study were as follows. 1. Total attrition area in Group I was larger than in Group II and III. 2. There was no significant difference in attrition area between right and left side in each group, but attrition area in Group III was larger than in Group I and II. 3. In Group I, Maxillary attrition area was larger than mandibular attrition area, but in Group ll and III, there was no significant difference in attrition area between maxilla and mandible. 4. In Group III, the attrition area of deviated side was target than undeviated side 5. There was no significant difference in attrition area between chewing side and non-chewing side in each group. 6. The total attrition area was unaffected by gender.

• The korean journal of orthodontics
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• v.33 no.5 s.100
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• pp.339-350
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• 2003

The purpose of this study was to investigate the micro-implant height and anterior hook height to prevent maxillary six anterior teeth from lingual tipping and extruding during space closure. We manufactured maxillary dental arch form, bracket and wire, using the computer aided three-dimensional finite element method. Bracket was $.022'{\times}.028'$ slot size and attached to tooth surface. Wire was $.019'{\times}.025'$ stainless steel and $.032'{\times}.032'$ stainless steel hook was attached to wire between lateral incisor and canine. Length of hook was 8mm and force application points were marked at intervals of In. Four micro-implants were implanted on alveolar bone between second premolar and first molar. The heights of them were 4, 6, 8, 10mm starting from wire. We analyzed initial displacement of teeth by various force application point applying force of 150gm to each micro-implant and anterior hook. The conclusions of 4his study are as the following : 1. When the micro-implant height was 4m and the anterior hook height was 5mm and below, anterior teeth were tipped lingually. When the anterior hook height was 6mm and above, anterior teeth were tipped labially. 2. When the micro-implant height was 6mm and the anterior hook height was 6mm and below, the anterior teeth were tipped lingually. When the anterior hook height was 6m and above, the anterior teeth were tipped labially. But lingual tipping of anterior teeth decreased and labial tipping Increased when the micro-implant height was 6mm, compared with 4mm micro-implant height. 3. When the micro-implant height was 8mm and the anterior hook height was 2mm, the anterior teeth were tipped lingually. When the anterior hook height was 3mm and above, labial tipping movement of the anterior teeth increased proportionally. 4. When the micro-implant height was 10mm and the anterior hook height was 2mm and above, labial tipping of the anterior teeth increased proportionally. 5. As the anterior hook height increased, aterior teeth were tipped more labially. But extrusion occurred on canine and premolar area because of the increase of wire distortion. 6. Movement of the posterior teeth was tipped distally during maxillary six anterior teeth retraction using micro-im plant because of the friction between bracket and were Based on the results of this study, we could predict the pattern of the tooth movement according to position of micro-implant and height of anterior hook. It seems that we can find the force application point for proper tooth movement in consideration of inclination of anterior anterior teeth, periodontal condition, overjet and overbite