• Restorative Dentistry and Endodontics
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• 제27권1호
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• pp.77-86
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• 2002

Current composites are made with dimethacrylate monomers and silane-treated silica microfillers, either alone or with silane treated glass fillers The main reasons for clinical failure of dental composites are secondary caries, wear and fracture. Most of practitioner want to get a composite which is more tougher under occlusal stress, less polymerization contraction, and better handling properties in application clinically. The aim of this study was to investigate the influence of resin matrix with various flows on the physical proper-ties such as fracture toughness and degree of conversion of the experimental resins. It was hypothesized that flexible or tough resin composites can be designed by judicious choice of monomer composition Various flow resin matrices containing Bis-GMA, UDMA, and TEG-DMA were made by altering the pro-portion of the monomers. After the unfilled resins were light-cured for different light intensity, the fracture toughness(K$_{1c}$) was measured according to ASTM standard using the single edge notched geometry, and degree of conversion(DC) was measured by FTIR. And experimental composites were formulated with variations in the proportion of silanated quartz and strontium glass fillers as 60, 75, and 77wt%. Also, the physical properties of composites with various filer contents were evaluated as same manner. All resulting data were compared by ANOVA/Tukeys test at 0.05 level. The results were as follows; 1. The degree of conversion of high flow resin containing less Bis-GMA was higher than that of low flow unfilled resin 2. While the degree of conversion of unfilled resin was increased according to light intensity for polymerization, there was no significant increase with moderate and high light intensity. Also, the fracture toughness was not increased by high light intensity. 3. The fracture toughness was high in the low flow unfilled resin containing higher contents of Bis-GMA. 4. There was a significant increase for fracture toughness and a tendency for degree of conversion to be reduced when the content of fillers was increased. 5. In the experimental composites, the flow of resin matrix did not affected on the fracture toughness, even, which was decreased as increase of viscosity. These results showed that the physical properties of a dental composite could be attributed to the flow of resin matrix with relative content of monomers. Specific combination of resin monomers should be designed to fulfil the needs of specific indication for use.

• Journal of Chest Surgery
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• 제37권3호
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• pp.245-251
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• 2004

심폐바이패스하 관상동맥우회술과 달리 심폐바이패스 없이 시행하는 관상동맥우회술의 경우 수술 후 혈액응고 기능이 항진되어 이식편의 혈전과 같은 문제가 발생되는 것이 우려된다. 비교연구를 통하여 심폐바이패스 없이 시행하는 관상동맥우회술 후 혈액응고기능이 항진되는지를 규명하고자 하였다. 2001년 11월부터 2002년 5월까지 관상동맥우회술을 시행받은 환자 중 심폐바이패스 없이 시행하는 관상동맥우회술을 시행받은 11명(I군, 연구군)과 같은 기간에 좌심실 심첨부와 중격의 무운동성으로 관상동맥우회술과 Dor 술식을 시행받은 11명의 환자들을(II군, 대조군)비교하였다. 술후 혈액응고기능이 항진되는지를 알아보기 위해 thromboelastography 검사를 수술 전, 술 후 1, 2, 3, 5일째 시행하여 r time, k time, $\alpha$ angle, MA값을 측정하였고 동시에 혈액응고기능검사, fibrinogen, D-dimer, protein S, protein C, antithrombin III, plasminogen, 혈소판 수 등을 시행하여 비교하였다. TEG검사의 각각의 변수값과 혈액응고기능검사 중 MA값, $\alpha$ angle, 혈소판수가 양 군 간 의미있는 차이를 보였다. MA값이 I군의 경우 술 후 3일과 5일째 140$\pm$72%와 153$\pm$98%로 증가하였으나 II군의 경우 87$\pm$27%와 78$\pm$28%로 감소하였다(p<0.05). $\alpha$ angle은 술후 3일째 I군이 122$\pm$92%로 증가하였고 II군이 69$\pm$23%로 감소하였다(p=0.09). 혈소판수는 술 후 3일째 I군이 63$\pm$55%였으며 II군이 33$\pm$13%였다(p<0.05). 심폐바이패스하 관상동맥우회술과 비교하여 심폐바이패스 없이 시행하는 관상동맥우회술의 경우 혈액응고기능이 항진되며 따라서 보다 적극적인 항응고치료의 필요성이 제기된다고 할 수 있다.