Vallittu P K
Department of Prosthetics and Stomatognathic Physiology, University of Kuopio, Faculty of Dentistry, Finland.
J Prosthet Dent. 1996 Jun;75(6):617-21. doi: 10.1016/s0022-3913(96)90246-2.
The aim of this study was to determine the dimensional accuracy and stability of denture base polymethyl methacrylate (PMMA), which was reinforced in various ways. Autopolymerizing PMMA and heat-cured PMMA were reinforced either with semicircular steel wire or with a prefabricated experimental reinforcement made of continuous E-glass fiber. Control specimens had no reinforcement. The width of each U-shaped test specimen was measured with a digital micrometer under a light microscope immediately after the test specimen was cured and when stored in water for 1, 2, 7, and 14 days. The results revealed that both the type of PMMA and the type of reinforcement affected the dimensional accuracy of the test specimens, especially after 7 and 14 days in water storage (p < 0.001). The greatest dimensional accuracy was found with the unreinforced test specimen made from autopolymerizing PMMA and with test specimens reinforced with the metal wire made from heat-cured PMMA. In terms of the width of the test specimens, the lowest dimensional accuracy was found in unreinforced and glass fiber reinforced specimens made from heat-cured PMMA. Storage in water did not affect the stability of the width (p > 0.1). The results suggest that the polymerization shrinkage of PMMA causes lower dimensional accuracy of the test specimens reinforced with glass fiber. This should be considered when glass-fiber reinforcement is used clinically.
本研究的目的是确定通过各种方式增强的义齿基托聚甲基丙烯酸甲酯（PMMA）的尺寸精度和稳定性。自凝PMMA和热凝PMMA分别用半圆形钢丝或由连续E玻璃纤维制成的预制实验增强材料进行增强。对照样本未进行增强。在测试样本固化后以及在水中储存1、2、7和14天时，立即在光学显微镜下用数字千分尺测量每个U形测试样本的宽度。结果显示，PMMA的类型和增强类型均会影响测试样本的尺寸精度，尤其是在水中储存7天和14天后（p < 0.001）。由自凝PMMA制成的未增强测试样本以及由热凝PMMA制成的金属丝增强测试样本的尺寸精度最高。就测试样本的宽度而言，由热凝PMMA制成的未增强和玻璃纤维增强样本的尺寸精度最低。储存在水中不会影响宽度的稳定性（p > 0.1）。结果表明，PMMA的聚合收缩会导致玻璃纤维增强测试样本的尺寸精度降低。临床上使用玻璃纤维增强材料时应考虑这一点。
