• 대한치과교정학회지
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• 제42권4호
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• pp.169-181
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• 2012

Objective: The purpose of this study was to develop superimposition method on the lower arch using 3-dimensional (3D) cone beam computed tomography (CBCT) images and orthodontic 3D digital modeling. Methods: Integrated 3D CBCT images were acquired by substituting the dental portion of 3D CBCT images with precise dental images of an orthodontic 3D digital model. Images were acquired before and after treatment. For the superimposition, 2 superimposition methods were designed. Surface superimposition was based on the basal bone structure of the mandible by surface-to-surface matching (best-fit method). Plane superimposition was based on anatomical structures (mental and lingual foramen). For the evaluation, 10 landmarks including teeth and anatomic structures were assigned, and 30 times of superimpositions and measurements were performed to determine the more reproducible and reliable method. Results: All landmarks demonstrated that the surface superimposition method produced relatively more consistent coordinate values. The mean distances of measured landmarks values from the means were statistically significantly lower with the surface superimpositions method. Conclusions: Between the 2 superimposition methods designed for the evaluation of 3D changes in the lower arch, surface superimposition was the simpler, more reproducible, reliable method.

• 대한심미치과학회지
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• 제28권1호
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• pp.4-17
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• 2019

우리나라 치과의 CBCT 보급률은 세계적으로 높은 편으로, 최근 1만대 보급을 돌파하고 있는 것으로 파악된다. 또한 최근 각 치과 제조업체마다 DLP방식의 In-House방식의 3D 프린터 보급률 또한 가파르게 상승하고 있다. 이에 맞춰 최근 개원가에서 CBCT와 구강 스캔 정보를 이용한 컴퓨터 가이드 임플란트 수술의 활용도가 증가하고 있는 상황이다. 현재 컴퓨터 가이드를 이용한 임플란트 수술 방법에 대해 문헌상 고찰을 통해 리뷰해보고, 또한 정확성 및 신뢰성이 보장되는 가이드 수술을 위한 고려사항에 대해 정리해보고자 한다.

• Journal of Oral Medicine and Pain
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• 제47권3호
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• pp.156-160
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• 2022

Temporomandibular joint (TMJ) ankylosis is a condition in which condylar movement is restricted because of fibrous or bony union between the mandibular condyle and temporal bone. TMJ ankylosis is most often caused by trauma, followed by systemic or local infection, and secondary to unknown causes. Diagnostic imaging plays a vital role in diagnosing TMJ ankylosis and establishing a treatment plan. Computed tomography (CT) or cone beam computed tomography (CBCT) is currently the imaging technique of choice to accurately demonstrate preoperative ankylosing masses and other surgically important findings, such as the shape of the mandibular condyle and the pathological changes in the joint. The osseous changes in the mandibular condyle are easily identified in the coronal and sagittal sections of CT or CBCT images. This report describes the case of a middle-aged woman who developed TMJ ankylosis of the left TMJ while undergoing repeated treatment for TMJ disease. We report the findings observed on radiographic and CBCT images through continuous observation.

• 한국의학물리학회지:의학물리
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• 제22권1호
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• pp.28-34
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• 2011

적응 방사선 치료(Adaptive Radiation Therapy, ART)를 실행하기 위한 고도의 정확성을 갖는 변형 영상 정합 방법은 필수이다. 본 연구의 목적은 Megavoltage cone-beam CT (MV CBCT)영상의 Intensity 변화를 통한 영상 정합의 정확성의 향상이다. Intensity 변화 값을 도출 하기 위해 kilovoltage CT (kV CT)와 MV CBCT를 이용하여 12 종류의 전자 밀도 바를 제공하는 Cheese 팬텀의영상을 획득하고, 영상들로부터 kV CT와 MV CBCT의 Hounsfield Unit (HU)값들의 관계를 도출하였다. MV CBCT 영상의 잡음을 감소하기 위해 Gaussian smoothing 필터를 적용하였다. MV CBCT영상의 intensity는 마치 동일한 모달리티에서 획득된 영상과 같은 kV CT와 동일한 범위의 intensity로 변화시켰다. 이후 두 영상에 효율적이고 사용하기 쉬운 intensity 기반의 데몬 영상 정합이 적용되었다. 본 연구실에서 인체 내 폐를 모사하도록 제작된 변형 폐 팬텀을 이용하여 위와 같은 방법을 적용하여 영상 정합을 하였다. Cheese 팬텀 영상, 변형 폐 팬텀 영상을 이용한 변형영상 정합 결과는 상관 계수가 각각 6.07%, 18% 향상되었다. 변형 폐 팬텀 영상의 변형 영상 정합 정확성을 평가하기 위해 추가적으로 측정된 팬텀 내부에 삽입한 표적의 중심 좌표를 이용하여vector 차이를 계산하였다. 벡터 차이는 $2.23{\pm}1.19mm$, $1.39{\pm}0.97mm$였다. 본 연구에서 사용한 intensity 변화 방법을 통해 변형 영상 정합의 정확성이 향상됨을 확인 하였고, 본 연구는 영상 정합 정확성을 향상시키기 위한 해결 방법이 될 수 있다. 차후 연구 계획도 본 연구 내용에 의해 제안되었다.

• 대한치과의사협회지
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• 제56권2호
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• pp.113-119
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• 2018

Trifid mandibular canal (TMC) is one of the anatomical variation of mandibular canal with clinical importance. An extra mandibular canal may explain inadequate anesthesis and be damaged causing paresthesia or bleeding during mandibular surgery. CBCT with high-level spatial resolution is an useful tool for the detection of mandibular canal and its variation. The aim of this report is to present a case of trifid mandibular canal with CBCT images and to give information on this anatomical variation of mandibular canal.

• Imaging Science in Dentistry
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• 제39권1호
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• pp.19-25
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• 2009

Purpose: To longitudinally observe the healing process of extracted socket and the alterations of the residual ridge in healthy adult dogs using cone beam CT (CBCT). Materials and Methods: The mandibular premolars of two beagle dogs were removed and the extraction sites were covered with the gingival tissue. CBCTs (3D X-ray CT scanner, Alphard vega, Asahi Co.) were taken at baseline and at 1 week interval for 12 weeks. Radiographic density of extracted wounds was measured on normalized images with a custom-made image analysis program. The amount of alveolar crestal resorption after the teeth extraction was measured with a reformatted three-dimensional image using CBCT. Bony healing pattern of extracted wound of each group was also longitudinally observed and analyzed. Results: Dimensional changes occurred during the first 6 weeks following the extraction of dogs' mandibular premolars. The reduction of the height of residual ridge was more pronounced at the buccal than at the lingual aspect of the extraction socket. Radiographic density of extracted wounds increased by week 4, but the change in density stabilized after week 6. New bone formation was observed at the floor and the peripheral side of extracted socket from week 1. The entrance of extracted socket was sealed by a hard-tissue bridge at week 5. Conclusion: The healing process of extracted wound involved a series of events including new bone formation and residual ridge resorption.

• Imaging Science in Dentistry
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• 제45권4호
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• pp.205-211
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• 2015

Purpose: This study was performed to compare the accuracy of micro-computed tomography (CT) and cone-beam computed tomography (CBCT) in detecting accessory canals in primary molars. Materials and Methods: Forty-one extracted human primary first and second molars were embedded in wax blocks and scanned using micro-CT and CBCT. After the images were taken, the samples were processed using a clearing technique and examined under a stereomicroscope in order to establish the gold standard for this study. The specimens were classified into three groups: maxillary molars, mandibular molars with three canals, and mandibular molars with four canals. Differences between the gold standard and the observations made using the imaging methods were calculated using Spearman's rho correlation coefficient test. Results: The presence of accessory canals in micro-CT images of maxillary and mandibular root canals showed a statistically significant correlation with the stereomicroscopic images used as a gold standard. No statistically significant correlation was found between the CBCT findings and the stereomicroscopic images. Conclusion: Although micro-CT is not suitable for clinical use, it provides more detailed information about minor anatomical structures. However, CBCT is convenient for clinical use but may not be capable of adequately analyzing the internal anatomy of primary teeth.

• Imaging Science in Dentistry
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• 제42권2호
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• pp.65-70
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• 2012

Purpose : The aim of this study was to compare the effective dose for imaging of mandible between multi-detector computed tomography (MDCT) and cone-beam computed tomography (CBCT). An MDCT with low dose technique was also compared with them. Materials and Methods : Thermoluminescent dosimeter (TLD) chips were placed at 25 organ sites of an anthropomorphic phantom. The mandible of the phantom was exposed using 2 different types of MDCT units (Somatom Sensation 10 for standard-dose MDCT, Somatom Emotion 6 for low-dose MDCT) and 3 different CBCT units (AZ3000CT, Implagraphy, and Kavo 3D eXaM). The radiation absorbed dose was measured and the effective dose was calculated according to the ICRP 2007 report. Results : The effective dose was the highest for Somatom Sensation 10 (425.84 ${\mu}Sv$), followed by AZ3000CT (332.4 ${\mu}Sv$), Somatom Emotion 6 (199.38 ${\mu}Sv$), and 3D eXaM (111.6 ${\mu}Sv$); it was the lowest for Implagraphy (83.09 ${\mu}Sv$). The CBCT showed significant variation in dose level with different device. Conclusion : The effective doses of MDCTs were not significantly different from those of CBCTs for imaging of mandible. The effective dose of MDCT could be markedly decreased by using the low-dose technique.

• 구강회복응용과학지
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• 제36권2호
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• pp.88-94
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• 2020

목적: 본 연구는 한국인에서 상악 전치의 치근 위치를 시상면에서 분석하고, 분류에 따른 빈도를 보고함으로써 즉시 식립 임플란트를 위한 방사선학적 자료를 수집하기 위함이다. 연구 재료 및 방법: 콘빔형 전산화단층영상(cone-beam CT)을 촬영한 환자 중 연구 기준에 적합한 120명(남성 60명, 여성 60명)을 대상으로 후향적 분석을 시행하였다. 축의 방향설정을 시행한 후에, 상악 전치부 치아와 치조골 사이의 관계에 대한 시상 치근 위치를 분석하였다. 치근이 치조골의 협측, 중앙, 구개측으로 위치한 경우 각각 Class I, II, III로 분류하였으며, 치근이 협측과 구개측 모두에서 피질골판에 2/3 이상 닿아있는 경우에는 Class IV로 하였다. 다음으로, 치아의 장축과 치조골의 장축 사이의 각도를 측정하였다. 기술적 분석 및 Kruskal-Wallis 분석을 시행하였으며, 치아의 위치 및 분류에 따른 시상각을 비교하였다. 결과: 상악 전치부의 시상 치근 위치에 대한 빈도분석 결과, Class I은 81.1%, Class II는 10.3%, Class III는 1.9%, 그리고 Class IV는 6.7%로 나타났다. 상악 전치부의 77.5%에서 시상각이 20도 이하로 나타났다. 그러나 견치의 경우, 42.7%에서 20도 이상의 시상각을 보였다. 분류에 따라서는 Class I (16.19)에서 Class II (8.72) 및 Class III (9.93)에 비해 통계학적으로 유의하게 높은 시상각을 보였으며, Class IV (3.79)에서 낮았다. 결론: 본 제한된 연구의 결과를 근거로, 상악 전치의 치근은 일반적으로 협측 치조골에 가깝게 위치하고 있으나, 일부 치아는 매우 얇은 치조골을 가지고 있으며, 30도 이상의 큰 시상각을 보였다. 따라서 적절한 치과 임플란트 치료 계획 수립을 위해 시상 치근 위치 및 시상각에 대한 cone-beam CT 분석이 필요할 것이다.

• Imaging Science in Dentistry
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• 제43권2호
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• pp.63-69
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• 2013

After over one decade development, cone beam computed tomography (CBCT) has been widely accepted for clinical application in almost every field of dentistry. Meanwhile, the radiation dose of CBCT to patient has also caused broad concern. According to the literature, the effective radiation doses of CBCTs in nowadays market fall into a considerably wide range that is from $19{\mu}Sv$ to $1073{\mu}Sv$ and closely related to the imaging detector, field of view, and voxel sizes used for scanning. To deeply understand the potential risk from CBCT, this report also reviewed the effective doses from literatures on intra-oral radiograph, panoramic radiograph, lateral and posteroanterior cephalometric radiograph, multi-slice CT, and so on. The protection effect of thyroid collar and leaded glasses were also reviewed.