Effect of intensity of light sources and barriers in ceramic hardness of dual-cured cement

AbstractIntroductionThe dual-cure resin cement is the main material for luting of ceramic. However, factors such as light source can influence the performance of the cement.ObjectiveEvaluate the influence of two light sources of different intensities on the microhardness of a resin cement when cured under different ceramics.Material and methodForty samples of dual resin cement were photoactivated by two LED light sources, with light intensity of 1000mW/cm² and 800mW/cm², respectively (40 seconds), under the base ceramic Zirconia, Spinel MgAl2O4 and Lithium Disilicate. In the control group, a glass plate was used. Each samples had the surface grounded (600 and 1200). After dry storage in the dark (24 hours), Vickers microhardness measurements were performed (HMV Shimadzu - 50gf/10 seconds). The data were submitted to factorial ANOVA and Tukey's test with significance level of 5%.ResultThe average hardness and standard deviation in the control group for cement polymerized 1000mW/cm² was 43.9±1.5 and 800mW/cm² the value of 43.4±1.3. The lowest value was for the Ceramic base of spinel MgAl2O4, light cured with 800mW/cm² with a value of 34.3±3.3.ConclusionThe ceramic type and intensity of the light source influence the hardness of the cement. The polymerization 1000mW/cm2 on the ceramic based on zirconia and spinel MgAl2O4 resulted in the best combination of hardness cement.

摘要与研究背景：双重固化树脂水门汀（dual-cure resin cement）是陶瓷粘接的核心材料，但光源等因素会对该水门汀的性能造成影响。
研究目的：评估两种不同光强的光源，在不同陶瓷基底下进行光固化时，对树脂水门汀显微硬度的影响。
材料与方法：选取40份双重固化树脂水门汀试样，分别置于氧化锆（Zirconia）、镁铝尖晶石（Spinel MgAl₂O₄）与二硅酸锂（Lithium Disilicate）三种陶瓷基底上，采用光强分别为1000mW/cm²与800mW/cm²的LED光源进行40秒的光固化处理；设置对照组，以玻璃板作为基底。所有试样表面均经600目、1200目砂纸打磨平整。将试样置于黑暗环境中干燥储存24小时后，采用维氏显微硬度计（HMV岛津，载荷50gf，保压10秒）开展显微硬度测试。采用析因方差分析（factorial ANOVA）与Tukey检验进行数据分析，显著性水平设定为5%。
研究结果：1000mW/cm²光固化组的对照组试样平均硬度及标准差为43.9±1.5，800mW/cm²光固化组的对照组试样平均硬度及标准差为43.4±1.3；最低硬度值出现在以800mW/cm²光固化的镁铝尖晶石（MgAl₂O₄）陶瓷基底组，其硬度值为34.3±3.3。
研究结论：陶瓷类型与光源光强均会对树脂水门汀的硬度产生显著影响；以1000mW/cm²光强对氧化锆及镁铝尖晶石（MgAl₂O₄）基底进行光固化时，可获得最佳的树脂水门汀硬度综合性能。