Takahashi J, Kitahara K, Teraoka F, Kubo F
Department of Dental Materials Science and Technology, Osaka University Faculty of Dentistry, Japan.
Int J Prosthodont. 1999 Jul-Aug;12(4):325-9.
The purpose of this study was to develop a material with low polymerization shrinkage for resin patterns to improve the fit of a long superstructure to implants.
Three different chemical substances were added at 1, 2, 3, 5, 10, and 20 wt% to the liquid component of a self-curing acrylic resin. Specimens for measuring shrinkage during self curing were prepared in a metal mold that took the form of a conical cavity with slightly tapered walls. The specimens were prepared using three different methods: (1) a brush-on technique, (2) an injection method, and (3) an injection-press method. The percentage of linear shrinkage was calculated from the protrusion of the specimen from the bottom of the cavity.
The injection-press method and the brush-on method gave the lowest polymerization shrinkage results (P < 0.05). The standard deviation of the former method was smaller than that of the latter. The linear shrinkage in the injection-press method decreased with the increase of the powder-to-liquid ratio (P < 0.05). All three additives reduced shrinkage to about 1/3 of the shrinkage of the basic resin using the injection-press method and a 2.00:1.00 powder-to-liquid ratio.
The addition of three different chemical substances to liquid reduces linear shrinkage to about 1/3 of the shrinkage of the original self-curing acrylic resin.
本研究的目的是开发一种用于树脂模型的低聚合收缩材料，以提高长型上部结构与种植体的适配性。
将三种不同的化学物质以1%、2%、3%、5%、10%和20%的重量百分比添加到自凝丙烯酸树脂的液体组分中。在一个呈锥形腔且壁稍呈锥形的金属模具中制备用于测量自凝过程中收缩率的标本。标本采用三种不同方法制备：（1）刷涂法，（2）注射法，（3）注射压制法。根据标本从腔底部的突出量计算线性收缩百分比。
注射压制法和刷涂法得到的聚合收缩率最低（P<0.05）。前一种方法的标准差小于后一种方法。注射压制法中的线性收缩率随粉液比的增加而降低（P<0.05）。使用注射压制法和2.00:1.00的粉液比时，所有三种添加剂都将收缩率降低至基础树脂收缩率的约1/3。
向液体中添加三种不同的化学物质可将线性收缩率降低至原始自凝丙烯酸树脂收缩率的约1/3。
