(A) clinical study of dental amalgam restoration : reasons for replacement and duration of primary reatoration

치의학과/석사[한글] 충전재료중 중 치과용 아말감은 비교적 조작이 간편하고, 물리적 성질이 충전재료로서 적당하며, 가격이 저렴하며, 오랫동안 쓰여져 왔고, 가장 널리 사용되고 있으나 도리어 그 때문에 임상에서 안이하게 취급하는 경향이 있어 이차우식의 발생이나 파절, 탈락, 크 기의 변화 및 변색, 부식현상 등으로 재충전을 요하는 경우가 야기된다. 이와 같은 경우 는 재료자체나 환자의 구강관리 여하에도 문제가 있겠으나 술자의 부주의, 부적절한 조작 이 더 큰 원인으로 지적되고 있다. 1977년부터 실시된 의료보험의 확대로 아말감 충전수요는 다른 충전 재료에 비해 그 이 전보다 현저히 증가되고 있으며, 재충전해야 할 경우는 더욱 격증하리라 예상된다. 이에 저자는 아말감 충전물의 재충전 이유나 재충전까지의 기간을 조사하는 것은 임상 에서 보다 좋은 치료를 위해 긴요한 과제라 믿어 1975년 1월부터 1977년 12월까지 이화여 자대학교 부속병원 치과에 내원한 환자 2,856명을 대상으로 치과병록부를 이용하여 재충 전한 아말감 260예중 단일 원인이고 기간이 명시되어 있는 205예의 재충전 이유 및 재충 전 때까지의 기간에 대해 조사하였다. 그 결과는 다음과 같다. 1. 내원환자의 전체충전물 중 58.5%는 아말감이였으며, 이 중 재충전을 한 것은 전체충 전 아말감의 15.13%이었다. 2. 아말감 재충전 이유로는 이차우식증이 56.10%, 파절이 27.80%, 탈락 8.78% 순이었다 . 3. 재충전 아말감의 52.2%가 3년 이내에, 70.7%가 5년이내에, 89.8%가 10년이내에 재충 전한 것으로 나타났고, 10년이 넘은후 재충전한 경우는 10.2%이었다. [영문] Ease of manipulation, adequate mechanical properties, long years of experience and economical cost are the factors which have established amalgam as the most widely used material for dental restorations. But amalgam restoration may require replacement because of secondary caries, fracture, "fall-out", dimensional change tarnish or corrosion etc. These failures of amalgam restorations seem to arise from failures during operations rather than from the inherent shortcomings of the material itself or of the patient's mismanagement. It is anticipated that restoration of amalgam and it's failures will both increase after more extensive utilization of the medical insurance which began in 1977. So, the author thinks that it would be helpful, for the development of better treatment in daily dental practice, to know the duration of amalgam restorations and the reasons for their replacement. The data for this survey was compiled from 2,856 out-patients of the Department of Dentistry, Ewha Woman's University Hospital from January 1975 to December 1977. 260 cases among 1, 718 fillings were studied, of which 205 cases both had a single reason for replacement and recognized the date of the previous filling. The results obtained were as follows; 1. Amalgam fillings were 58.5 percent of all dental restorative materials. Of these, 15.13 percent of the amalgam restorations had to be replaced. 2. Among those amalgms requiring replacement, 52.2 percent had been in place less than 3 years, 70.7 percent within 5 years and 89.8 percent had been in place less than 10 years. Only 10.2 percent had been in place more than 10 years.restrictio

Feasibility of High_Frame-Rate Ultrasound for Thyroid Elastography

MasterThyroid nodules are a very common clinical problem. Thyroid cancer is becoming the most common cancer among Korean women, surpassing breast cancer. a fine-needle aspiration (FNA) biopsy is recommended because FNA is the standard procedure for the preoperative evaluation of thyroid nodules. However, FNA is costly, and a large percentage (approximately 70%) of these FNAs turn out to be benign findings. Thus, it would be beneficial to reduce the number of FNAs on many benign nodules. US elastography has the potential to make a noninvasive differential diagnosis between benign and malignant thyroid nodules. With the conventional US imaging method, when the tissue motion or deformation occurs quickly (e.g., shear wave elasticity imaging or cardiac strain rate imaging), the frame rate may not be high enough to track this fast tissue deformation. Therefore, high-frame-rate US imaging methods have been developed. One of the most widely used methods in achieving high-frame-rate US is to use unfocused US beams (i.e., flash imaging). In this paper, we presents feasibility of high frame rate US for thyroid elastography whether it can provide additional information compared to conventional US imaging or not. We observed that the sum of the power spectral densities for a normal thyroid gland is larger than that for a benign nodule in the frequency range higher than 100 Hz(p < 0.05). It seems that the difference in the power spectral density sums between a normal thyroid gland and a benign nodule result from the presence of a high frequency range. We also found that the sum of power spectral densities depended on the ROI selection (distance from carotid artery and ROI size). Based on these study results, further investigations are required on data acquisition from subject with consistent view of a thyroid gland to reduce the ROI dependency of the power spectral density and on reducing undesirable motion from patients' respiration and / or transducer. To increase a confidence level of our feasibility study, enough data acquisition ( over 50 data set ) and various signal analysis methods would be needed