Meriç Gökçe, Ruyter I Eystein
Department of Prosthetic Dentistry, Institute of Clinical Dentistry, University of Oslo, Oslo, Norway.
Dent Mater. 2008 Aug;24(8):1050-7. doi: 10.1016/j.dental.2007.12.003. Epub 2008 Feb 1.
The purpose was to investigate the effect of water storage and thermal cycling on the flexural properties of differently sized unidirectional fiber-reinforced composites (FRCs) containing different quantities of fibers. The effect of fiber orientation on the thermal expansion of FRCs as well as how the stresses in the composites can be affected was considered.
An experimental polymeric base material was reinforced with silica-glass fibers. The cleaned and silanized fibers were sized with either linear PBMA-size or crosslinked PMMA-size. For the determination of flexural properties and water uptake, specimens were processed with various quantities of differently sized unidirectional fibers. Water uptake of FRC was measured. Water immersed specimens were thermally cycled for 500 and 12,000 cycles (5 degrees C/55 degrees C). Flexural properties of "dry" and wet specimens with and without thermal cycling were determined by a three-point bending test. The linear coefficients of thermal expansion (LCTE) for FRC samples with different fiber orientations were determined using a thermomechanical analyzer.
Water uptake of the FRC specimens increased with a decrease in fiber content of the FRC. Flexural properties of FRCs improved with increasing fiber content, whereas the flexural properties were not influenced significantly by water and thermal cycling. Fiber orientation had different effects on LCTE of FRCs. Unidirectional FRCs had two different LCTE in longitudinal and transverse directions whereas bidirectional FRCs had similar LCTE in two directions and a higher one in the third direction.
The results of the study suggest that the surface-treated unidirectional silica-glass FRC can be used for long-term clinical applications in the oral cavity.
本研究旨在探讨水储存和热循环对不同尺寸、含不同纤维量的单向纤维增强复合材料（FRC）弯曲性能的影响。同时考虑纤维取向对FRC热膨胀的影响以及复合材料中的应力如何受到影响。
用二氧化硅玻璃纤维增强一种实验性聚合物基体材料。清洁并硅烷化后的纤维用线性PBMA尺寸或交联PMMA尺寸进行上浆处理。为了测定弯曲性能和吸水率，制备了含不同数量、不同尺寸单向纤维的试样。测量FRC的吸水率。将浸泡在水中的试样进行500次和12000次热循环（5℃/55℃）。通过三点弯曲试验测定“干燥”和湿态、有无热循环的试样的弯曲性能。使用热机械分析仪测定不同纤维取向的FRC样品的线性热膨胀系数（LCTE）。
FRC试样的吸水率随FRC纤维含量的降低而增加。FRC的弯曲性能随纤维含量的增加而提高，而水和热循环对弯曲性能没有显著影响。纤维取向对FRC的LCTE有不同影响。单向FRC在纵向和横向上有两种不同的LCTE，而双向FRC在两个方向上有相似的LCTE，在第三个方向上有更高的LCTE。
研究结果表明，表面处理的单向二氧化硅玻璃FRC可用于口腔的长期临床应用。
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