Medical Faculty, Centre of Dentistry, Department of Operative and Preventive Dentistry and Endodontics, Heinrich-Heine-University, Moorenstr. 5, Geb. 18.13, 40225 Düsseldorf, Germany.
Clin Oral Investig. 2010 Oct;14(5):599-605. doi: 10.1007/s00784-009-0316-y. Epub 2009 Jul 21.
The objective of this study was to investigate the effect of exposure time on color stability of resin-based restorative materials when polymerized with quartz-tungsten halogen light (QTH) or light-emitting diode light (LED). Eight samples of Ceram-X Mono, Dyract eXtra, and Tetric EvoCeram each were cured for 10, 20, and 60 s with QTH or LED. The CIE-Lab values (L*, a*, b*) were measured prior to and after performing water storage or a Suntest, and ΔL, Δa, Δb, and ΔE were calculated. Statistical analysis (p < 0.05) showed significant changes of the color values after each of the aging processes as well as between ΔL, Δa, Δb, and ΔE of the materials in dependence of the curing device, exposure time, aging condition, and material formulation. LED performed similarly or even better with 10-s exposure time than QTH with 20 s. No improvement of color stability was achieved with increasing exposure time of 60 s either for LED or for QTH. Exposure time, emission spectrum of the light-curing device, as well as the individual material formulation influence color stability. There is apparently an exposure time above which the individual material formulation, especially type and amount of photoinitiator or synergist, dominate the color stability.
本研究旨在探讨暴露时间对石英钨卤素灯（QTH）和发光二极管灯（LED）聚合时树脂基修复材料颜色稳定性的影响。分别用 QTH 或 LED 将 8 个 Ceram-X Mono、Dyract eXtra 和 Tetric EvoCeram 样本各固化 10、20 和 60 s。在进行水储存或日晒试验前后测量 CIE-Lab 值（L*、a*、b*），并计算 ΔL、Δa、Δb 和 ΔE。统计分析（p<0.05）表明，每种老化处理后以及在固化设备、暴露时间、老化条件和材料配方的影响下，材料的颜色值均发生显著变化。对于 10 s 的曝光时间，LED 的性能与 20 s 的 QTH 相当，甚至更好。对于 LED 和 QTH，增加曝光时间至 60 s 并不能提高颜色稳定性。暴露时间、光固化设备的发射光谱以及个别材料配方均会影响颜色稳定性。显然，存在一个暴露时间，超过该时间后，各个材料配方，尤其是光引发剂或增效剂的类型和数量，会主导颜色稳定性。
