Park S H, Lee C S
Yonsei University, College of Dentistry, Department of Conservative Dentistry, Seoul, Korea.
Oper Dent. 1996 Sep-Oct;21(5):213-7.
This study was designed to determine the changes in the degree of conversion throughout composite resins of varying thicknesses after heat curing and to evaluate whether or not the thin wafer technique that was applied in this study was sensitive to changes in distance from the light source. A 5 mm-in-diameter hole was made in a 4 mm-thick Teflon plate, and composite resin was placed in the hole and light cured from the top for 60 seconds. Twenty samples were prepared; 10 of these were additionally heat cured in an inlay oven. After light curing or light and heat curing, the samples were sectioned into four parts and assigned to groups A, B, C, or D according to their distance from the light source. These sections were then thinned to 50-70 microns, and analyzed by use of a standard baseline technique with a Fourier Transform Infrared Spectrometer (FT-IR) to determine the degree of conversion. The degree of conversion diminished as the distance from the light source increased; however, once the samples were heat cured, significant increases in the degree of conversion were noted throughout the samples. In the heat-cured composites, the degree of conversion in the outer portion of the sample was higher than in the inner portion. The thin wafer technique with FT-IR is considered to be a reliable method for measuring the degree of conversion in a composite resin, because changes between groups were clearly noted.
本研究旨在确定热固化后不同厚度复合树脂的转化率变化程度，并评估本研究中应用的薄晶片技术是否对距光源距离的变化敏感。在一块4毫米厚的聚四氟乙烯板上钻一个直径5毫米的孔，将复合树脂放入孔中并从顶部光固化60秒。制备了20个样品；其中10个另外在嵌体炉中进行热固化。在光固化或光热固化后，将样品切成四部分，并根据它们与光源的距离分为A、B、C或D组。然后将这些切片减薄至50 - 70微米，并使用傅里叶变换红外光谱仪（FT - IR）的标准基线技术进行分析，以确定转化率。转化率随着距光源距离的增加而降低；然而，一旦样品进行了热固化，整个样品的转化率显著提高。在热固化的复合材料中，样品外部的转化率高于内部。使用FT - IR的薄晶片技术被认为是测量复合树脂转化率的可靠方法，因为组间变化明显。
