Biomaterials Research Group, The University of Manchester, School of Dentistry, UK. lara
Dent Mater. 2011 Feb;27(2):173-9. doi: 10.1016/j.dental.2010.10.002. Epub 2010 Nov 18.
To investigate the surface integrity of solvent-challenged ormocer-matrix composites, photoactivated by different light exposure modes, through surface-hardness measurements at different periods of time; and to compare such behavior with dimethacrylate-based materials.
One hundred percent ormocer-based matrix (experimental ormocer (ORM)), a commercial mixed dimethacrylate-ormocer-based matrix (Admira (ADR)) and two commercial dimethacrylate-based matrix composites (experimental controls, (Grandio (GRD) and Premise (PRE)) were evaluated. Disk specimens (4 mm × 2 mm) were prepared from each material and light-activated using either a standard (S) or soft-start (SS) light exposure protocol with an LED-curing unit. Top, irradiated surface Knoop hardness (KHN) was measured within the following experimental groups (n=5): Group 1: immediately after exposure; Group 2: after dry and dark storage, Group 3: after storage in distilled water, and Group 4: immersion in absolute ethanol. Hardness of Groups 2-4 were measured after 7 days storage. Immediate hardness values were submitted to Student's t-tests separately for each material. Hardness values after treatments were submitted to two-way ANOVA and Tukey's post hoc test to compare values among different storage media and light exposure mode protocols. Comparisons among materials were described using percentage of hardness change. Statistical testing was performed at a pre-set alpha of 0.05.
Immediate hardness values were not affected by the light exposure mode, regardless of the material. In general, exposure mode did not significantly affect hardness after 7 days storage, regardless of storage media or material. After 7 days dry storage, hardness values increased for all materials relative to immediate testing, and decreased after water and ethanol storage, with ethanol showing the greatest effect. The experimental ormocer-based material had the lowest percentage hardness change and thus proved more resistant to solvent degradation than the other materials, regardless of the light exposure method.
Irradiated surface hardness values and surface integrity were unaffected by light exposure mode, regardless of the material tested. The experimental ormocer-based material presented the least change in hardness as a result of solvent challenge than any of the commercial products: ormocer or conventional resin-based, and thus showed better surface integrity.
通过不同时间段的表面硬度测量，研究不同光暴露模式下受溶剂挑战的有机硅氧烷基质复合材料的表面完整性，并将其与二甲基丙烯酸酯基材料进行比较。
评估了 100%有机硅氧烷基基质（实验性有机硅氧烷（ORM））、一种商业混合二甲基丙烯酸酯-有机硅氧烷基基质（Admira（ADR））和两种商业二甲基丙烯酸酯基基质复合材料（实验对照物，（Grandio（GRD）和Premise（PRE））。从每种材料中制备出直径为 4 毫米×2 毫米的圆盘试件，并使用 LED 固化单元，采用标准（S）或软启动（SS）光暴露方案进行光激活。在以下实验分组中（n=5），测量顶部照射表面的努氏硬度（KHN）：第 1 组：照射后立即；第 2 组：干燥和黑暗储存后；第 3 组：储存在蒸馏水中后；第 4 组：浸入无水乙醇中。第 2-4 组在储存 7 天后测量硬度。对每种材料的即时硬度值分别进行学生 t 检验。对不同储存介质和光暴露模式方案之间的硬度值进行双因素方差分析和 Tukey 事后检验。用硬度变化百分比来描述材料之间的比较。统计检验的预设 alpha 值为 0.05。
无论材料如何，即时硬度值均不受光暴露模式的影响。一般来说，无论储存介质或材料如何，7 天干燥储存后，暴露模式对硬度没有显著影响。在 7 天的干燥储存后，所有材料的硬度值相对于即时测试都有所增加，在水和乙醇储存后则下降，其中乙醇的影响最大。基于实验性有机硅氧烷的材料的硬度变化百分比最低，因此与其他材料相比，它对溶剂降解的抵抗力更强，无论采用何种光暴露方法。
无论测试材料如何，照射表面的硬度值和表面完整性不受光暴露模式的影响。基于实验性有机硅氧烷的材料在受到溶剂挑战时，其硬度变化最小，比任何商用产品（有机硅氧烷或传统树脂基）都要好，因此具有更好的表面完整性。
