• 대한소아치과학회지
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• 제32권4호
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• pp.644-648
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• 2005

과잉치는 정상치판(dental lamina)의 과도한 증식의 결과로 발생되어 가족적 성향을 보이며, 쇄골두개이형성(Cleidocranial dysplasia), Gardner 증후군 등의 여러 질환과 관련되어 나타나기도 한다. 그 빈도는 유치열에서 $0.3{\sim}0.8%$, 영구치열에서 $1.0{\sim}3.5%$이고, 남성에서 호발되며(2 : 1), 상악에서 더 많이 발생한다(9 : 1). 상악에서는 mesiodens라고 불리는 중절치 사이의 위치가 가장 흔한 부위이고, 그 다음은 fourth molar와 측절치 부위이다. 하악에서는 소구치 부위가 가장 흔한 부위이고 전치부위에서는 약 2%로 매우 드물게 발생한다. 과잉치의 만기 잔존은 치간 이개, 인접한 치아의 맹출 장애, 치근 흡수 등을 야기하고 과잉치와 관련되어 함치성 낭종이 발생될 수 있으므로 조기진단과 적절한 치료가 중요하다. 본 두 증례는 비교적 드물게 나타나는 하악에 발생한 과잉치로, 하악 전치부와 소구치부에 발생한 과잉치를 발거하고 교정치료를 시행하여 양호한 결과를 얻었기에 보고하는 바이다.

• 대한치과교정학회지
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• 제46권4호
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• pp.242-252
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• 2016

Objective: Orthodontic mini-implants (OMI) generate various horizontal and vertical force vectors and moments according to their insertion positions. This study aimed to help select ideal biomechanics during maxillary incisor retraction by varying the length in the anterior retraction hook (ARH) and OMI position. Methods: Two extraction models were constructed to analyze the three-dimentional finite element: a first premolar extraction model (Model 1, M1) and a residual 1-mm space post-extraction model (Model 2, M2). The OMI position was set at a height of 8 mm from the arch wire between the second maxillary premolar and the first molar (low OMI traction) or at a 12-mm height in the mesial second maxillary premolar (high OMI traction). Retraction force vectors of 200 g from the ARH (-1, +1, +3, and +6 mm) at low or high OMI traction were resolved into X-, Y-, and Z-axis components. Results: In M1 (low and high OMI traction) and M2 (low OMI traction), the maxillary incisor tip was extruded, but the apex was intruded, and the occlusal plane was rotated clockwise. Significant intrusion and counter-clockwise rotation in the occlusal plane were observed under high OMI traction and -1 mm ARH in M2. Conclusions: This study observed orthodontic tooth movement according to the OMI position and ARH height, and M2 under high OMI traction with short ARH showed retraction with maxillary incisor intrusion.

• Imaging Science in Dentistry
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• 제34권2호
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• pp.63-67
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• 2004

Purpose: To make a focal trough (image layer) for an average maxillary dental arch of 6-year-old korean in panoramic radiography. Materials and Methods : Phantom for the maxillary dental arch was designed using intercanine width, intermolar width, tooth size, and interdental spacing to record the data of 6-year-old child. The characteristics of pre-corrected panoramic machine (for adult) was evaluated using the phantom, resolution test pattern for margin of the image layer, and metal ball for the center of the image layer. Panoramic image layer of the child was developed by means of decreasing the speed of film-cassette and positioning the phantom backwards, and then the characteristics of post-corrected panoramic machine (for child) were reevaluated. Results: At post-corrected panoramic image layer, beam projection angles at all interdental areas increased for about 2.6-3.8°, the position of the image layer was shifted toward the rotation center for about 2.5 mm at the deciduous central incisior area. The width of image layer decreased at all areas. Conclusion : Increased beam projection angle will reduce the disadvantage of tooth overlap, and the same form between the center of the image layer and dental arch will improve image resolution.

• 대한소아치과학회지
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• 제31권1호
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• pp.52-58
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• 2004

과잉치는 유치열에서 0.3-0.8%, 영구치열에서 1.0-3.5% 정도로 발생하며, 2:1로 남자에게 호발 9:1로 상악에서 호발한다. 그 중 하악 전치부에서 발생하는 빈도는 전체 과잉치중에서 2-4%의 매우 낮은 빈도를 보인다고 보고되었다. 과잉치가 계속 존재할 경우 나타날 수 있는 합병증으로서 치간이개, 인접한 정상치아의 맹출장애, 치관의 형성이상, 인접치의 치근흡수, 함치성 낭종 등을 들 수 있으며, 치열 발육 중인 어린이의 경우 성장 중임을 감안하여 바람직한 교합유도를 위한 정확한 진단과 함께 적절한 처치가 필요하다. 본 증례는 전북대학교병원 소아치과에 내원한 6세 환아의 하악 전치부에서 발견된 양측성 매복 과잉치로서 그 중 한개는 영구치와 융합된 경우를 보고하는 바이다.

• 대한치과교정학회지
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• 제49권6호
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• pp.349-359
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• 2019

Objective: The aim of this study was to analyze three-dimensional (3D) changes in maxillary dentition in Class II malocclusion treatment using arch wire with continuous tip-back bends or compensating curve, together with intermaxillary elastics by superimposing 3D virtual models. Methods: The subjects were 20 patients (2 men and 18 women; mean age 20 years 7 months ${\pm}$ 3 years 9 months) with Class II malocclusion treated using $0.016{\times}0.022-inch$ multiloop edgewise arch wire with continuous tip-back bends or titanium molybdenum alloy ideal arch wire with compensating curve, together with intermaxillary elastics. Linear and angular measurements were performed to investigate maxillary teeth displacement by superimposing pre- and post-treatment 3D virtual models using Rapidform 2006 and analyzing the results using paired t-tests. Results: There were posterior displacement of maxillary teeth (p < 0.01) with distal crown tipping of canine, second premolar and first molar (p < 0.05), expansion of maxillary arch (p < 0.05) with buccoversion of second premolar and first molar (p < 0.01), and distal-in rotation of first molar (p < 0.01). Reduced angular difference between anterior and posterior occlusal planes (p < 0.001), with extrusion of anterior teeth (p < 0.05) and intrusion of second premolar and first molar (p < 0.001) was observed. Conclusions: Class II treatment using an arch wire with continuous tip-back bends or a compensating curve, together with intermaxillary elastics, could retract and expand maxillary dentition, and reduce occlusal curvature. These results will help clinicians in understanding the mechanism of this Class II treatment.

• 대한치과교정학회지
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• 제52권5호
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• pp.313-323
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• 2022

Objective: This study aimed to estimate the clinical effects of different types of bone-anchored maxillary protraction devices by using a network meta-analysis. Methods: We searched seven databases for randomized and controlled clinical trials that compared bone-anchored maxillary protraction with tooth-anchored maxillary protraction interventions or untreated groups up to May 2021. After literature selection, data extraction, and quality assessment, we calculated the mean differences, 95% confidence intervals, and surface under the cumulative ranking scores of eleven indicators. Statistical analysis was performed using R statistical software with the GeMTC package based on the Bayesian framework. Results: Six interventions and 667 patients were involved in 18 studies. In comparison with the tooth-anchored groups, the bone-anchored groups showed significantly more increases in Sella-Nasion-Subspinale (°), Subspinale-Nasion-Supramentale(°) and significantly fewer increases in mandibular plane angle and the labial proclination angle of upper incisors. In comparison with the control group, Sella-Nasion-Supramentale(°) decreased without any statistical significance in all treated groups. IMPA (angle of lower incisors and mandibular plane) decreased in groups with facemasks and increased in other groups. Conclusions: Bone-anchored maxillary protraction can promote greater maxillary forward movement and correct the Class III intermaxillary relationship better, in addition to showing less clockwise rotation of mandible and labial proclination of upper incisors. However, strengthening anchorage could not inhibit mandibular growth better and the lingual inclination of lower incisors caused by the treatment is related to the use of a facemask.

• 대한치과교정학회지
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• 제48권1호
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• pp.3-10
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• 2018

Objective: The purpose of this study was to predict the optimal bending angles of a running loop for bodily protraction of the mandibular first molars and to clarify the mechanics of molar tipping and rotation. Methods: A three-dimensional finite element model was developed for predicting tooth movement, and a mechanical model based on the beam theory was constructed for clarifying force systems. Results: When a running loop without bends was used, the molar tipped mesially by $9.6^{\circ}$ and rotated counterclockwise by $5.4^{\circ}$. These angles were almost similar to those predicted by the beam theory. When the amount of tip-back and toe-in angles were $11.5^{\circ}$ and $9.9^{\circ}$, respectively, bodily movement of the molar was achieved. When the bend angles were increased to $14.2^{\circ}$ and $18.7^{\circ}$, the molar tipped distally by $4.9^{\circ}$ and rotated clockwise by $1.5^{\circ}$. Conclusions: Bodily movement of a mandibular first molar was achieved during protraction by controlling the tip-back and toe-in angles with the use of a running loop. The beam theory was effective for understanding the mechanics of molar tipping and rotation, as well as for predicting the optimal bending angles.

• 대한소아치과학회지
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• 제35권2호
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• pp.376-381
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• 2008

성장기 아동의 치열은 대부분 혼합 치열로, 이 시기에는 유치 탈락 또는 계승치 미맹출로 인해 치열에 빈 공간이 많아지고, 계승치가 맹출되었다 하더라도 고정성 장치를 부착시키고 강한 호선을 적용시키기는 매우 어렵다. 이런 치료 진행의 문제점을 해결하기 위해 horseshoe 장치가 유용하게 사용될 수 있다. 이 장치는 치열에 빈 공간이 있는지의 여부에 관계없이 장치 제작이 가능하며, 치열 상태와 무관하게 전 치열을 하나로 묶어준다. 그리고 구강내에 이미 맹출된 치아의 모든 치면을 피개하므로 치아의 정출과 회전이 발생하지 않으면서 악간 고무줄의 힘에 의해 치조골의 골개조가 상악과 하악 치궁에서 서로 반대 방향으로 유도된다. 경희대학교 치대병원 소아치과에 내원한 환아에서, Horseshoe Appliance를 이용하여 III급 부정교합에서 양호한 결과를 얻었기에 보고하는 바이다.

• 대한치과교정학회지
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• 제35권5호
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• pp.371-380
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• 2005

제1소구치 또는 제2소구치 발치 후 발치공간 폐쇄 시 치아이동의 양상 즉, 치아이동방향과 이동량을 구명하는 것이 본 연구의 목적이었다. 상악 우측 인공 치조골부에 제1소구치 또는 제2소구치를 제외한 중절치부터 제2대구치 까지 실험용 치아들을 식립하고 bull loop이 형성된 반쪽 호선에 15도의 gable bend를 부여한 후 전치부를 후방견인하여 발츠공간을 폐쇄시켰다. 실험 전후에 교합면 방사선사진과 시상면 방사선사진을 촬영하고 인공치조골부 하단에 식립된 기준표지점에 중첩하여 이동방향 및 이동량을 계측하였다. 그 결과 제2소구치 발치군의 전치부후방이동량이 제1소구치 발치군에 비해 더 적었으며 구치부의 고정원 소실 및 고정원의 근심설측회전량은 제2소구치 발치군에서 더 크게 나타났다.

• 대한치과교정학회지
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• 제53권2호
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• pp.125-136
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• 2023

Before progress was recently made in the application of temporary anchorage devices (TADs) in bio-mechanical design, orthodontists were rarely able to intrude molars to reduce upper posterior dental height (UPDH). However, TADs are now widely used to intrude molars to flatten the occlusal plane or induce counterclockwise rotation of the mandible. Previous studies involving clinical or animal histological evaluation on changes in periodontal conditions after molar intrusion have been reported, however, studies involving human histology are scarce. This case was a Class I malocclusion with a high mandibular plane angle. Upper molar intrusion with TADs was performed to reduce UPDH, which led to counterclockwise rotation of the mandible. After 5 months of upper molar intrusion, shortened clinical crowns were noticed, which caused difficulties in oral hygiene and hindered orthodontic tooth movement. The mid-treatment cone-beam computed tomography revealed redundant bone physically interfering with buccal attachment and osseous resective surgeries were followed. During the surgeries, bilateral mini screws were removed and bulging alveolar bone and gingiva were harvested for biopsy. Histological examination revealed bacterial colonies at the bottom of the sulcus. Infiltration of chronic inflammatory cells underneath the non-keratinized sulcular epithelium was noted, with abundant capillaries being filled with red blood cells. Proximal alveolar bone facing the bottom of the gingival sulcus exhibited active bone remodeling and woven bone formation with plump osteocytes in the lacunae. On the other hand, buccal alveolar bone exhibited lamination, indicating slow bone turnover in the lateral region.