• 치과방사선
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• 제21권2호
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• pp.261-273
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• 1991

This study was undertaken to document and better defined this condition to help clarify this clinical and radiographical appearances by the analysis of clinical and radiographical features of fibro-osseous lesions in the jaws. A study was made of a series of 128 cases with fibro-osseous lesions. The obtained results were as follows. 1. Fibrous dysplasia of the jaws occurred with equal predilection for males and females. But the females occurred in 68% of cemento-ossifying fibroma and 75% of periapical cemental dysplasia. 2. 43% of fibrous dysplasia and 32% of cemento-ossifying fibroma occurred in the 2nd decades and 33% of periapical cemental dysplasia in 5th decades. 3. 62% of fibrous dysplasia occurred in the maxilla, 73% of cemento-ossifying fibroma in mandible, 90% of periapical cemental dysplasia in mandible. 4. 98% of fibrous dysplasia occurred in premolar-molar region, 77% of cemento-ossifying fibroma in molar region, 68% of periapical cemental dysplasia in incisor region. 5. In serial radiographic features, mature stage were 55% of fibrous dysplasia, 45% of cemento-ossifying fibroma, 59% of periapical cemental dysplasia. 6. 87% of fibrous dysplasia had monostotic lesion, 67% of periapical cemental dysplasia had multiple lesions. 7. In fibrous dysplasia and cemento-ossifying fibroma, migration of tooth occurred in 61.7% and 36.4%, retention of tooth occurred in 4.3% and 9.1%, loss of lamina dura occurred in 6.4% and 9.1%, and root resorption had not occurred in fibrous dysplasia, but occurred in 18% of cemento-ossifying fibroma, displacement of mandibular canal occurred in 14.9% and 31.8%.

• 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.

• 한국해양공학회지
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• 제28권4호
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• pp.314-323
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• 2014

In this study, a gearbox and blade were modeled in the MASTA program, and the housing and carrier components were modeled using a finite element method. Using substructure synthesis, all the components were combined and used to establish a vibration model of a 2.5-MW wind turbine gearbox. In addition, the safety displacement factor was evaluated using an AGMA data sheet about bearing's outer race for the input shaft and output shaft. As a result, the bearing's outer race for the input shaft, and the radial and axial responses were satisfied by the $1^{st}$ and $2^{nd}$ planetary gears and the $3^{nd}$ helical gear transmission error(TE), respectively. However, the output shaft support bearing's outer race responses were not satisfied with the radial response by the $2^{nd}$ TE and axial response by the $3^{rd}$ TE. To reduce the vibration, tooth modification was needed. After profile tooth modification, at the outer race of the output shaft support bearing, the radial response was reduced by approximately $20{\mu}m$, and the axial response was reduced by approximately $6{\mu}m$.

• 대한소아치과학회지
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• 제44권1호
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• pp.99-107
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• 2017

유착된 유구치의 치료에 있어 조기 진단이 매우 중요하다. 유착으로 인하여 발생된 저위교합을 방치하는 경우 교합적인 문제가 생길 수 있으므로 정기검진을 통한 진단과 이에 따른 적절한 치료가 필요하다. 저위교합 된 유구치의 치료 방법으로 정기검진, 보존적 접근, 보철적 수복, 발치를 수반한 공간획득 등이 있다. 본 증례에서는 상악 제2유구치의 유착으로 인하여 제2소구치 치배의 변위를 보이는 두 명의 환아를 대상으로 이환치의 발거를 먼저 시행하고 고정성 혹은 가철성 교정장치를 이용하여 공간확장술을 함으로써 변위 되었던 제2소구치 치배의 정상 맹출을 유도하였으며 장기간에 걸쳐 부작용이 없었음을 보고하는 바이다.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제29권2호
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• pp.135-139
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• 2003

저자 등은 본과에 내원하여 함치성 낭종으로 진단된 5명의 소아 환자에서 보존적인 조대술을 이용하여 매복된 영구치를 발거하지 않고 이차 치유를 유도하였다. 술 후 병소는 신생골로 치유되었으며 매복 영구치도 정상적인 위치로 맹출하였다. 이와 같이 소아에서 함치성 낭종의 경우 주기적인 예후 관찰이 가능하다면 보다 보존적인 조대술 등을 이용시에는 영구치의 정상적인 유도와 낭종의 치유를 유도할 수 있으리라 사료된다. 또한 인접치아의 경사 등에 의한 정상적인 치아의 맹출이 어려운 경우에는 교정치료와 병행시에 정상적인 영구 치열을 확보할 수 있을 것으로 사료되어 문헌고찰과 함께 보고하는 바이다.

• 대한소아치과학회지
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• 제31권1호
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• pp.46-51
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• 2004

Talon cusp는 전치부의 치관부에 부가적으로 생성된 교두양 구조물로서 치과이상중 하나이다. Talon cusp는 비심미성, 교합 장애, 치아변위, 발육부의 우식으로 인한 치수 괴사 및 치근단 병변 등을 야기할 수 있다. 그밖에 교모나 치주적인 문제, 혀에의 자극, 그리고 턱관절 동통등의 문제점을 야기할 수 있다. 따라서, Talon cusp의 정확한 조기 진단이 필요하며 각각의 증례에 맞는 처치를 통해 Talon cusp로 인한 문제점을 방지할 수 있다. 본 증례는 각각 영구전치와 유전치에 형성된 Talon cusp로서 이차 상아질을 유도하면서 점차적으로 교두를 삭제하는 치료와 근관 치료를 동반해 교두를 완전 절단하는 치료를 시행하였다.

• 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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• 제23권3호
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• pp.375-389
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• 1993

The delivery of optimal orthodontic treatment is greatly influenced by a clinician's ability to predict and control tooth movement achieved by applying known force systems to the dentition. It is important to determine the location of the center of resistance of a tooth or group of teeth to better understand the nature of their displacement characteristics under the various force levels. The purpose of this study was to define the location of the centers of resistance of various units of the upper anterior segment for lingually directed 100gm and 200gm force in a dry human skull. The units investigated were composed of four incisors and six anterior teeth. In addition, the effect of change in force magnitude on the location of the center of resistance of these units was investigated. The laser reflection technique was used to measure the initial displacements of the consolidated teeth under loading. The results were as follows: 1. The instantaneous center of resistance for the four anterior teeth was located vertically between level 4 and level 5-that is, at $37.4\%$ apical to the cementoenamel junction level. 2. The instantaneous center of resistance for the six anterior teeth was located vertically just beneath level 5-that is, at $50.3\%$ apical to the cementoenamel junction level. 3. Increasing force levels had little effect on the location of the center of resistance of a given unit. 4. The location of the instantaneous center of resistance shifted apically as the number of dental units consolidated increased.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제45권6호
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• pp.332-342
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• 2019

Objectives: Socket grafting is vital to prevent bone resorption after tooth extraction. Several techniques to prevent resorption have been described, and various bone graft substitutes have been developed and used with varying success. We conducted this pilot study to evaluate the performance of nanohydroxyapatite (nHA) derived from chicken eggshells in socket preservation. Materials and Methods: This was a prospective, single center, outcome assessor-blinded evaluation of 23 sockets (11 patients) grafted with nHA and covered with platelet-rich fibrin (PRF) membrane as a barrier. Bone width and radiographic bone density were measured using digital radiographs at 1, 12, and 24 weeks post-procedure. Postoperative histomorphometric and micro-computed tomography (CT) evaluation were performed. The study protocol was approved by the Institutional Ethics Committee. Results: All patients had uneventful wound healing without graft material displacement or leaching despite partial exposure of the grafted socket. Tissue re-epithelialized with thick gingival biotype (>3 mm). Width of the bone was maintained and radiographic density increased significantly with a trabecular pattern (73.91% of sockets) within 12 weeks. Histomorphometric analysis showed 56.52% Grade 3 bone formation and micro-CT analysis revealed newly formed bone with interconnecting trabeculae. Conclusion: Use of a PRF membrane with nHA resulted in good bone regeneration in sockets. Use of a PRF membrane prevents periosteal-releasing incisions for primary closure, thereby facilitating the preservation of keratinized mucosa and gingival architecture. This technique, which uses eggshell-derived nHA and PRF membrane from the patient's own blood, is innovative and is free of disease transfer risks. nHA is a promising economic bone graft substitute for bone regeneration and reconstruction because of the abundant availability of eggshell waste as a raw material.

• 대한치과보철학회지
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• 제62권2호
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• pp.174-182
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• 2024

다수의 구치를 상실한 환자에서는 전방부 치아들의 마모나 변위, 교합평면의 붕괴와 교합수직고경의 감소가 일어날 수 있다. 특히 편측으로 소수의 치아만 가진 경우 국소의치는 생역학적으로 불리하므로, 소수의 임플란트 서베이드 크라운을 추가한 임플란트 보조 국소의치가 대안이 될 수 있다. 본 증례의 환자는 하악 우측 구치부 상실로 인해 전방부 치아들이 심하게 마모되고, 교합평면이 붕괴되어 있었다. 최소한의 교합 수직고경 거상과 함께 상악 고정성 보철 및 하악 임플란트 보조 국소의치로 수복을 진행하였고, 기능적 및 심미적으로 양호한 임상 결과를 얻을 수 있었다.