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황현식,Hwang, Hyeon-Shik 대한치과보철학회 2000 대한치과보철학회지 Vol.38 No.4
A treatment should be functional, esthetic, conservative and periodontally healthy in order to meet criteria of an ideal dental procedure. In a prsthodontic patient with horizontal and/or vertical space deficiency, orthodontic tooth movement should be considered as a pre-prosthetic procedure. With a conventional technique, orthodontic treatment is a time-consuming and uncomfortable procedure. Pre-prosthetic orthodontic treatment, however, is no longer difficult procedure with the help of recently developed techniques, such as passive bracketing. The present article outlines the problems and causes of horizontal and vertical space deficiency in prosthodontic patients, and presents efficient pre-prosthetic orthodontic treatment modalities with typical clinical cases.
성인 전치부 부분교정을 위한 새로운 교정장치 MTA의 이용
황현식(Hyeon-Shik Hwang),전현란(Hyun-Ran Jeon),김석필(Seok-Pil Kim),김왕식(Wang-Sik Kim),이계형(Gye-Hyeong Lee) 대한치과의사협회 2011 대한치과의사협회지 Vol.49 No.7
With an increase of public"s perception on “minimally invasive dentistry”, more patients are demanding orthodontic alignment of anterior teeth rather than restorative treatment which is more invasive. One draw back of orthodontic alignment has been that it takes long time. To overcome this limitation, a new orthodontic device named Mini-Tube Appliance (MTA), have been developed. With the combined use of light NiTi wire and inter-proximal stripping, rapid anterior alignment can be obtained efficiently. This article presents the use of MTA for rapid alignment of anterior teeth and its clinical guidelines with typical case samples.
2차원 방사선 규격사진에서 하악골 상행지 고경의 보정분석에 관한 3차원 CT 영상 연구
황현식(Hyeon-Shik Hwang),김형민(Hyung-Min Kim),이기헌(Ki-Heon Lee),임회정(Hoi-Jeong Lim) 대한치과교정학회 2007 대한치과교정학회지 Vol.37 No.1
안면비대칭 환자의 진단 및 치료계획 수립 시 하악골 상행지 고경의 좌우 차이를 정확히 판정하는 것이 필요하다. 본 연구는 2차원 방사선사진에서 정면 상행지경사도 및 측면 상행지경사도를 이용하여 하악골 상행지 고경을 보정하는 방법이 비대칭 판정에 도움이 되는지 알아보고자 시행되었다. 이부 편위가 있는 안면비대칭자 40명을 대상으로 정모두부방사선규격사진을 촬영하고 좌우 각각의 하악골 상행지 고경을 측정하는 한편 정모 및 측모 방사선사진에서 계측된 정면 상행지 경사도 및 측면 상행지 경사도를 이용하여 상행지 고경을 3차원적 개념으로 보정한 후, 실제 3차원 영상에서의 비대칭 판정 결과와 비교 분석을 시행하였다. 측정결과, 정면 및 측면 상행지 경사도는 이부 편위측에 비하여 반대측에서 크게 나타났으며 보정 후 상행지 고경의 좌우 차이는 증가하는 양상을 나타내었다. 보정 전 그리고 보정 후 각각에서 상행지 고경의 좌우비대칭 여부를 판정한 후, 3차원 영상에서의 판정을 기준으로 하여 보정에 따른 sensitivity, specificity 그리고 accuracy 변화를 살펴본 결과, specificity는 44%에서 22%로 감소하였으나 sensitivity는 74%에서 94%로 증가하는 것으로 나타났다. 아울러 accuracy가 보정 전 68%에서 보정 후 78%로 증가하는 것으로 나타나 정면 및 측면 상행지 경사도를 이용하여 상행지 고경을 3차원적 개념으로 보정할 경우, 이는 보다 정확한 비대칭 판정에 유용함을 보여주었다. Objective: Defining right and left side differences in mandibular ramus height is one of the key elements in the diagnosis of facial asymmetry. The purpose of the present study was to evaluate the effect of correction of ramus height with frontal and lateral ramal inclinations (FRI and LRI) in 2-dimensional cephalograms and observe how this affects the diagnostic accuracy of asymmetry.<br> Methods: Frontal and lateral cephalograms were obtained in 40 individuals with chin deviation. FRI and LRI were measured on each side and ramus height measurement was corrected with these inclinations using Pythagorean’s theorem. The results of diagnosis before and after correction on cephalograms were compared with the results in 3D CT images.<br> Results: Both FRI and LRI showed greater values in the contralateral side than in the chin-deviated side and these contributed to an increase in the right and left side ramus height differences. After comparison of diagnostic results before and after correction on cephalograms with the results on 3D CT images, the sensitivity increased significantly (from 74 to 94 %) whereas the specificity decreased (from 44 to 22 %). Overall accuracy increased from 68 to 78 % with the correction using FRI and LRI.<br> Conclusion:The results of the present study indicate that correction of ramus height with FRI and LRI is useful for an accurate diagnosis of facial asymmetry on frontal cephalograms.
성숙가토의 관절원판후조직 절단 후 하악골의 위치변화가 악관절에 미치는 영향에 관한 연구
황현식(Hyeon-Shik Hwang),손병화(Byung-Wha Sohn) 대한치과교정학회 1992 대한치과교정학회지 Vol.22 No.2
The purpose of this experiment was to study the effects of changes of mandibular position on temporomandibular joint in internal derangement patients. Twenty-four female New Zealand White Rabbits, weighing over 3.5kg, were utilized in this study. Bilateral temporomandibular joint surgery was performed in twenty one of the rabbits to displace disc anteriorly through incising the retrodiscal tissue 1-2mm posterior to the disc, thus inducing internal derangement. They were divided into three groups: nine were left untreated after surgery, six were fitted with functional protrusive appliances 4 weeks after surgery, and six wore collar appliances to apply 4 ounces of mandibular retractive force per side 4 weeks after surgery. The remaining three served as the control group. Histologic examinations were performed after sacrificing them by threes at 4-week intervals. The results were as follows: 1. Histologic findings similar to internal derangement were observed in the rabbits whose retrodiscal tissues had been incised. 2. In the rabbits untreated after surgery, articular surface on condylar process and articular eminence showed severe erosion and deformation, and displaced disc manifested changes in both shape and internal architecture. 3. Functional protrusion after surgery resulted in progressive remodeling on posterosuperior portion of condyle and glenoid fossa, while it also brought about erosion on articular eminence and anterior portion of condyle. 4. Mandibular retraction after surgery resulted in compression of retrodiscal tissue and regressive remodeling of posterior portion of condyle.
방사선상 enhancement 정도에 따른 측모두부방사선규격사진 계측점 설정의 재현도
유황석(Hwang-Sog Ryu),황현식(Hyeon-Shik Hwang) 대한치과교정학회 2002 대한치과교정학회지 Vol.32 No.1
본 연구는 측모두부방사선규격사진의 디지털 영상을 enhancement하였을 때 계측점 설정의 재현도를 비교 평가하여 두부방사선사진 계측점 설정에 도움이 되고자 시행되었다. 10명의 측모두부방사선규격사진을 촬영하여 컴퓨터에 입력하고 Quick Ceph Image Pro<sup>TM</sup>에서 gray-scale equali zation number를 50으로, detail enhancement numbe를 50으로 설정하여 방사선상을 4단계까지 enhancement하였다. 5명의 조사자가 모니터 상에서 32개의 계측점을 설정하고 방사선상의 각 enhancement 단계에서 각 계측점에 대하여 5명의 조사자가 설정한 점과 이 점들의 중심점간의 거리인 편위량으로 조사자간 계측점 설정의 재현도를 비교 평가하여 다음과 같은 결과를 얻었다. 1. Enhancement를 하지 않은 방사선상에서 조사자간 재현도는 계측점에 따라 다양하게 나타났다. 2. 방사선상 enhancement에 따른 계측점의 편위량을 비교한 결과, 5개의 계측점에서 방사선상의 enhancement 단계간에 조사자간 계측점 설정의 재현도가 통계적으로 유의한 차이를 보였다. 3. 계측점 pterygomaxillary fissure는 enhancement 단계 1과 2의 방사선상에서, 계측점 posterior nasal spine은 enhancement 단계 1의 방사선상에서, 계측점 menton은 enhancement 단계 2,3과 4의 방사선상에서 조사자간 계측점 설정의 재현도가 enhancement하지 않은 영상에 비하여 높게 나타났다. 이상의 결과로 모니터 상에서 측모두부방사선규격사진의 계측점 설정시 디지텅 방사선상의 enhancement를 통하여 일부 계측점에서 재현도를 증가시킬 수 있음을 알 수 있었다. The purpose of this study was to evaluate the reproducibility of lateral cephalometric landmarks according to radiographic image enhancement, and to contribute to the identification of cephalometric landmarks. Lateral cephalograms of ten individuals were taken and stored into computer. The images were then enhanced up to four grades by Quick Ceph Image Pro TM on condition that the gray-scale equalization number was 50 and the detail enhancement number was 50. After thirty two landmarks were identified on monitor images by five observers, the deviations from the mean, the distances estimated between identified points and the mean point of five identified points, were evaluated for each landmark at each enhancement grade. Through the statistical analysis, following results were obtained. 1. In case of unenhanced radiographic images, the inter-observer reproducibility of the landmarks showed a large variation. 2. The comparison of deviation from the mean according to the degree of radiographic image enhancement for each landmark showed that the inter-observer reproducibility was significantly different at 5 landmarks. 3. The landmark of pterygomaxillary fissure showed higher reproducibility at enhancement grade 1 and 2 images than at unenhanced images. So did the landmark of posterior nasal spine at enhancement grade 1 images, and the landmark of menton at enhancement grade 2, 3 and 4 images respectively. The above results suggest that the reproducibility of some landmarks can be increased by radiographic image enhancement during the identification of the lateral cephalometric landmarks on the monitor.