Wang Yan, Darvell B W
Department of Prosthodontics, Guanghua School of Stomatology, Sun Yat-sen University, Guang Zhou, China.
Dent Mater. 2008 Sep;24(9):1223-9. doi: 10.1016/j.dental.2008.02.002. Epub 2008 Mar 21.
To investigate the load-bearing capacity and failure mode of various types of glass ionomer cement (GIC) under Hertzian indentation, exploring the relationship between the failure behavior and formulation, and examining claims of filler-reinforcement of GIC.
Discs 2mm thick, 10mm diameter, 8-18 replicates, were fabricated for two filler-reinforced GICs, four unmodified and unreinforced GICs, and four resin-modified GICs, with a dental silver amalgam and a filled-resin restorative material for comparison. Testing was at 23 degrees C, wet, after 7d storage at 37 degrees C in artificial saliva at pH 6, using a 20mm diameter hard steel ball and filled-nylon substrate (E: 10GPa). First failure was detected acoustically; mode was determined visually. At least 1/3 of specimens in each case were examined under scanning electronic microscope for corroboration.
Reinforced and unmodified-unreinforced GICs were indistinguishable by failure load (one-way analysis of variance, P=0.425, overall 260+/-70N) and mode. Failure loads for resin-modified GICs were 360-1150N, amalgam approximately 680N, and filled resin approximately 1200N. Resin-modified GICs tended to be tougher (incomplete fracture), all others gave complete fracture (radial cracking). The stronger materials (two resin-modified GICs and filled resin) showed some cone cracking.
While resin-modified GICs showed various extents of increase of failure load over that of the plain GICs, consistent with the hybrid chemistry, filler-reinforcement was not evident for the two claimed products, consistent with structural and theoretical expectations.
研究各类玻璃离子水门汀（GIC）在赫兹压痕下的承载能力和失效模式，探讨失效行为与配方之间的关系，并检验GIC填料增强的说法。
制作了厚度为2mm、直径为10mm的圆盘，每种材料制作8 - 18个复制品，包括两种填料增强型GIC、四种未改性且未增强的GIC以及四种树脂改性GIC，同时制作牙科银汞合金和填充树脂修复材料作为对照。在37℃的pH值为6的人工唾液中储存7天后，于23℃潮湿环境下进行测试，使用直径20mm的硬钢球和填充尼龙基板（弹性模量E：10GPa）。首次失效通过声学检测；失效模式通过目视确定。每种情况下至少1/3的试样在扫描电子显微镜下检查以进行验证。
增强型和未改性 - 未增强型GIC在失效载荷（单因素方差分析，P = 0.425，总体为260±70N）和失效模式方面无明显差异。树脂改性GIC的失效载荷为360 - 1150N，银汞合金约为680N，填充树脂约为1200N。树脂改性GIC往往更坚韧（不完全断裂），其他所有材料均发生完全断裂（径向开裂）。强度较高的材料（两种树脂改性GIC和填充树脂）出现了一些锥形开裂。
虽然树脂改性GIC的失效载荷比普通GIC有不同程度的增加，这与混合化学原理相符，但对于两种声称具有填料增强作用的产品，填料增强并不明显，这与结构和理论预期一致。
