Evaluation of color stability of different temporary restorative materials

AbstractIntroductionTemporary restorative materials are widely used, however, little is know about their color stability.Objectiveto evaluate the color stability of the following temporary restorative materials: acrylic and bis-acrylic resins after immersion in pigmenting solutions for different periods of storage.Material and methodFour materials were tested (Dêncor/Clássico, Protemp 4/3M ESPE; Structur 2 SC/Voco; Luxatemp AM Plus/DMG) and 30 test specimens (15 mm in diameter and 2 mm thick) per material were fabricated. They were divided according to the storage medium (artificial saliva, saliva + cola type soda, and saliva + coffee) and storage time intervals (2, 5, 7 and 15 days). Color measurements were made before and after immersions, with use of a spectrophotometer, by means of the CIE L*a*b* system. The data were analyzed by the analysis of variance and the Tukey Test, at a level of significance of 5%.ResultAcrylic resin presented greater color stability in comparison with bis-acrylic resins (p<0.001). When bis-acrylic resins were compared no significant difference was observed between the resins Structur and Luxatemp (p=0.767). As regards solutions tested, coffee showed the highest color change values (p<0.001), and the longer the storage time interval, the greater was the color change in all the temporary restorative materials analyzed (p<0.001).ConclusionAcrylic resin presented greater color stability in comparison with bis-acrylic resins (p<0.001). Coffee caused the greatest color change, and immersion time was determinant in color stability of the temporary materials analyzed.

引言：临时修复材料（temporary restorative materials）应用广泛，但目前学界对其颜色稳定性（color stability）的认知仍较为有限。
目的：本研究旨在评估丙烯酸树脂（acrylic resins）与双丙烯酸树脂（bis-acrylic resins）两类临时修复材料，经不同时长浸泡于着色溶液（pigmenting solutions）后的颜色稳定性。
材料与方法：本研究共测试4种临时修复材料，分别为Dêncor/Clássico、Protemp 4/3M ESPE、Structur 2 SC/Voco及Luxatemp AM Plus/DMG；每种材料制备30个直径15 mm、厚度2 mm的试件（test specimens）。将试件按存储介质（人工唾液（artificial saliva）、唾液+可乐类碳酸饮料（cola type soda）、唾液+咖啡）与存储时长（2、5、7、15天）进行分组。采用分光光度计（spectrophotometer）基于CIE L*a*b*色空间系统（CIE L*a*b* system），在浸泡前后对试件进行颜色测量。采用方差分析（analysis of variance）与Tukey检验（Tukey Test）对数据进行统计学分析，显著性水平设定为5%。
结果：相较于双丙烯酸树脂，丙烯酸树脂的颜色稳定性更优（p<0.001）。在双丙烯酸树脂的组间比较中，Structur与Luxatemp两种材料的颜色稳定性无显著差异（p=0.767）。就本次测试的着色溶液而言，咖啡引发的颜色变化程度最高（p<0.001）；且所有受试临时修复材料的颜色变化程度均随存储时长的延长而显著升高（p<0.001）。
结论：丙烯酸树脂的颜色稳定性优于双丙烯酸树脂（p<0.001）；咖啡对试件的颜色改变作用最为显著，且浸泡时长是影响受试临时修复材料颜色稳定性的关键因素。