• The korean journal of orthodontics
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• v.28 no.3 s.68
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• pp.379-389
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• 1998

The purpose of the present study was to evaluate the change of tooth mobility following orthodontic tooth movement. Six orthodontic patients which had been treated with edgewise appliance were used. Tooth mobility was measured with Periostest at the time of the removal of orthodontic appliance and 1, 2, 3, 4, 6, 8, 10, 12, 16, 20, 24 weeks after appliance removal. Following results were obtained: 1. Tooth mobility upon the removal of orthodontic appliance showed individual variation while incisor showed greater mobility than the other teeth. 2. Tooth mobility showed continued decrease pattern until 24 weeks after appliance removal. 3. While maxillary incisors showed continued decrease pattern during the study period, the other teeth showed steep decline pattern during the first 12 weeks and gentle slope during the second 12 weeks. 4. The tooth mobility of the maxillary second premolar showed the most typical change in terms of the consistency of the decline. 5. There were no significant differences of tooth mobility between heavy- and light-contacted anterior teeth during experimental period. The results of the present study suggested that periodontal reorganization is not completed even in 24 weeks following orthodontic tooth movement.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.4
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• pp.686-692
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• 2006

The impacted teeth were surgically exposed by the closed-eruption technique and orthodontically retracted. The subject of this study are 24 patients(Mx. insiors; 10 Mx. canines; 14) who finished their treatment. The periodontal condition of the impacted teeth and the normally erupted proximal and opposed teeth were compared and analysed. The results are the followings ; 1. When the gingival index, plaque index, pocket depth and attached gingiva in periodontal evaluation were compared, there was no significant difference between the study group and the control group (P>0.05). 2. When the alveolar bone support of the mesial and the distal surface of the maxillary central incisors and proximal teeth was compared, there was no significant difference between the study group and the control group (P<0.05). 3. When the alveolar bone support of the maxillary canines was compared, there was no significant difference between the retracted teeth and the normally erupted teeth(P>0.05). The results above showed that the surgical exposure by closed-eruption technique followed by the orthodontic retraction of the impacted teeth has a positive influence on the regeneration of gingival tissue in clinical practice and is esthetically more stable. And it is considered that the clinicians should give attention to the direction of retraction power and the maintenance of normal shape of the alveolar bone in treatment of maxillary central incisors.

• The Journal of Korean Academy of Prosthodontics
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• v.48 no.2
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• pp.94-100
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• 2010

Purpose: The purpose of this study was to compare the fracture strength of the zirconia ceramic crowns according to tooth position. Material and methods: After 10 metal dies were made for each group, the zirconia ceramic crowns were fabricated using CAD/CAM system ($Lava^{TM}$ All-Ceramic System) and each crown was cemented on each metal die with resin cement (Rely $X^{TM}$ Unicem). The cemented zirconia ceramic crowns mounted on the testing jig were inclined with 30 degrees to the long axis of the tooth and the universal testing machine was used to measure the fracture strength. Results: 1. The fracture strength of the zirconia ceramic crown in the lower 1st molar (2963 N) had the highest and that in the lower central incisor (1035 N) had the lowest. 2. The fracture strength of zirconia ceramic crown was higher than that of the IPS Empress crowns in all tooth position. 3. The fracture mode of the crowns was similar. Most of fracture lines began at the loading area and extended through proximal surface perpendicular to the long axis of the crowns. 4. There were no significant differences on the fracture strength of the zirconia ceramic crowns according to tooth position except in premolar group. Conclusion: Within the limitations of this study, the results suggested that strength of zirconia ceramic crown is satisfactory for clinical use.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.3
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• pp.534-547
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• 2006

Ectopic eruption and impaction of canines is a frequently encountered clinical problems. The incidence of impaction ranges between 1-3%. The cause of canine impaction can be the result of localized factors or can be a polygenic multifactorial inheritance and associated with other dental anomalies. The general dentist and pediatric dentist should know how to properly diagnose and manage potential disturbances in the eruption of maxillary canine. Diagnosis of impacted canine at age 8-10 years can significantly reduce serious ramifications, including surgical exposure and orthodontic traction as well as root resorption of the lateral incisors. Extraction of primary canine would be one of the method to prevent the impaction. The surgical procedure should be designed to minimize the destruction of periodontal tissue of impacted canine. Closed eruption technique is thought to be optimal method of surgical exposure compared with other methods. An overview of the incidence, sequela as well as the surgical periodontal, and orthodontic consideration in the management of impacted canine was presented.

• The korean journal of orthodontics
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• v.38 no.2
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• pp.95-103
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• 2008

Objective: This study was performed to investigate the labio/buccal clinical crown curvatures of Korean permanent teeth and to obtain the curve-ratio data in an attempt to fabricate bracket bases fit for each individual Korean permanent tooth. Methods: Three-dimensional digital models were made from 30 sets of dental casts with normal anatomic structures. According to the FA points, horizontal and vertical reference planes were established and lines were drawn on the tooth surfaces in reference to these planes. The curvature was expressed as the coefficient of a quadratic equation. Lines mesial, distal, gingival and occlusal to the horizontal, vertical reference planes and the FA point were drawn. Results: The curvature measured for each line revealed that there are no significant differences between male and female, except for maxillary canines and maxillary second bicuspids (p > 0.05). There were notable differences in the mesio-distal or gingivo-occlusal curvatures among the mandibular lateral incisors, maxillary canines, maxillary and mandibular first and second bicuspids and first molars (p < 0.05). Conclusions: The labial & buccal crown curvatures of teeth in Korean normal occlusion were measured on the mesial and distal, gingival and occlusal sides respectively in this study. Based on these data, a SWA can be developed to fit the individual features of Korean tooth crowns.

• 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.

• The korean journal of orthodontics
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• v.40 no.5
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• pp.334-341
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• 2010

Objective: The purpose of this study was to evaluate morphologic differences in the mandibular arch between Egyptian and Korean subjects. Methods: The Egyptian sample consisted of 94 mandibular casts (35 Class I, 32 Class II and 27 Class III). The Korean sample consisted of 462 mandibular casts (114 Class I, 119 Class II, and 135 Class III). The most facial portion of 13 proximal contact areas was digitized from photocopied images of the mandibular dental arches. Clinical bracket points were calculated for each tooth. The subjects were grouped according to arch form to compare the frequency distribution of the 3 arch forms between the ethnic groups in each Angle classification. Results: Egyptians had significantly narrower intermolar and intercanine widths ($p$ < 0.001), and shallower intermolar and intercanine depths ($p$ < 0.001) than Koreans. There was an even frequency distribution of the 3 arch forms within the Egyptian group ($p$ = 0.46). However, in the Korean group, the most frequent arch form was the square arch form (46.7%), while the frequency of the tapered arch form was significantly lower (18.8%). Conclusions: These results might provide helpful information in evaluating morphologic differences between ethnic groups in selection of preformed superelastic archwires.

• Journal of Periodontal and Implant Science
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• v.36 no.1
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• pp.239-251
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• 2006

결합조직이식을 이용한 치근피개 술식에 많은 관심이 집중되고 있다. 최근에는 acellular dermal matrix가 자가 결합조직 이식편의 대체물로써 소개되었다. 본 실험의 목적은 치근피개를 위해 acellular dermal matrix을 사용시, 그 임상 효과 빚 조직 치유 양상을 평가하고, 이를 자가 결합조직 이삭시의 결과와 비교하기 위함이다. 3마리의 성견에 인위적인 치은 퇴축부 형성을 위해서, 상악 좌우견치의 협측에서 각화치은을 모두 제거하고, 법랑백악경계부로부터 12mm 정도 치조골을 삭제한 후에 판막을 봉합하였다. 그 후 35일을 치유 기간으로 부여하였다. 총 6 부위의 결손부가 실험에 포함되었고, 각각 3 부위씩이 대조군과 실험군으로 분류되었다. 실험군에서는 acellular dermal matrix 이식과 치관측 변위 판막을 시행하였고, 대조군에서는 치은 퇴축부위에 자가 결합조직 이식과 치관측 변위 판막을 시행하였다. 치주낭 깊이, 임상적 부착 수준, 치은 퇴축 높이, 각화조직 높이 등을 인위적 결손부 형성전, 치은 피개술 시행 직전, 피개술 시행후 4주 경과시에 각각 측정하였다. 술후 4주시에, 상악 좌우 견치 부위에서 시편을 얻어 조직학적으로 관찰하고 Wilcoxon signed rank test 와 Mann-Whitney U test으로 통계처리하였다. 임상결과 관찰시, 대조군과 실험군 모두에서, 술전과 비교시 치은 퇴축 감소와 각화조직의 증가, 임상 부착수준의 개선이 나타났다.(p ( 0.05) 평균 치근 피개율은 실험군에서 61.33(5.67%(n=3), 대조군에서 55.67(5.67%(n=3) 이었고, 대조군과 실험군에서 임상결과에서는 통계학적으로 유의성 있는 차이는 없었다.(p ( 0.05). 조직학상으로는, 두 군 모두에서 이식편이 수여부에 잘 융화되어 있었고 비슷한 치유 양상을 보였다. 이상의 실험결과에 의하면, Acellular dermal matrix은 치근피개술 시행시에 결합조직 이식편의 대용품으로 사용할 수 있고 비슷한 피개 결과를 얻을수 있었다.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.4
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• pp.535-539
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• 2000

Ectopic eruption of a tooth into the oral environment occurs commonly whereas ectopic eruption of a tooth into other sites is rare. Those that have been reported include the nasal cavity, chin, mandibular condyles, coronoid processes, orbits and maxillary sinus. The etiologic factors of ectopic eruption are developmental disturbances such as cleft palate and teeth displaced by trauma or cysts, maxillary infection, genetic factors, crowding and exceptionally dense bone. In many cases, however, the etiology cannot be identified. Eruption of the teeth into the maxillary sinus is uncommon, however the identification of such teeth can be important since they have the potential to cause considerable morbidity. The definitive treatment is surgical removal of the teeth. A 7 year-old-boy visited the Department of Pediatric Dentistry, College of Dentistry, Yonsei University for treatment of dental caries. The abnormal erupting paths of the left and right maxillary canines were found during routine panoramic radiographic investigations. A panoramic radiograph taken at 13 years old revealed that two maxillary canines were located into the sinus. The teeth were extracted by the Caldwell-Luc approach.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.4
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• pp.696-706
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• 2003

The purpose of this study was to clarify the palatal forms through palatal curvatures of right to left, anterior to posterior direction, and difference of right and left palatal volumes in the primary and permanent dentition. Samples were consisted of normal occlusion of both dentition(50 males and 50 females each). Their upper plaster casts were used, measuring points were decided, through 3-dimensional laser scanning(3-D Laser Scanner, DS4060, LDI, U.S.A.), and fitting standard horizontal plane were made for measuring the height and sectioned volumes of palate. The results were as follows: 1. Palatal volume and height were greater at the right side of the palate in the primary and permanent dentition of male and female, but there was no significance. 2. Palatal height was greater in male compared to female, especially, there was significant difference at intercuspid, inter-second premolar area in the permanent dentition(P<0.05). 3. To the height of A-P direction of mid-palatal area, the highest point was 20mm in the primary dentition, 30mm in the permanent dentition from interdental papilla of central incisors. 4. Palatal height of inter-cuspid and inter-second premolar became shallow and broad, high and broad each, compared to inter-deciduous canine and inter-second deciduous molar.