de A Souza Morganna B, Briso André Lf, de Oliveira-Reis Bruna, Dos Santos Paulo H, Fagundes Ticiane C
Department of Restorative Dentistry, UNESP - São Paulo State University, Araçatuba School of Dentistry, Araçatuba, SP, Federative Republic of Brazil.
Department of Dental Materials and Prosthodontics, UNESP - São Paulo State University, Araçatuba School of Dentistry, Araçatuba, SP, Brazil.
J Contemp Dent Pract. 2019 Feb 1;20(2):204-210.
The aim of this study was to evaluate microhardness and color change (ΔE) of composite resins, light cured with different light emission diodes (LEDs) and submitted to artificial accelerated aging (AAA).
Two composite resins with lucirin- TPO photoinitiator were selected: Tetric N-Ceram (Ivoclar Vivadent, A1) and Vit-l-escence (Ultradent, WO).A resin with the only camphorquinone photoinitiat or was chosen as a negative control: Filtek Z350XT (3M ESPE, WD). Disc-shaped specimens were prepared (5 mm diameter; 1.5 mm thick) and photopolymerized with an LED with one wavelength (Radii-Cal, SDI) or multiple wavelengths (Valo, Ultradent), for each composite resin (n = 10). Surface microhardness and color evaluations were performed immediately after specimen preparation and after AAA. Microhardness results were analyzed using Kruskal-Wallis and Mann-Whitney tests for multiple comparisons. To compare the evaluation of microhardness at different times, the Wilcoxon test was used. Mean values of ΔE, ΔL, Δa, and Δb were evaluated using two-way analysis of variance (ANOVA), and Tukey test for multiple comparisons (a = 0.05).
Regarding microhardness, a statistically significant difference between the two LEDs was observed for Vit-lescence after AAA. When comparing composite resins that were light-cured with the same device, FiltekZ350XT obtained the greatest microhardness. All groups presented a statistically significant decrease in microhardness from the initial time to the AAA. Regarding ΔE, no statistically significant difference between the two LEDs was observed. When comparing composite resins, FiltekZ350XT showed the highest ΔE values.
In general, an LED with multiple wavelengths influenced the microhardness of only one resin containing lucirin-TPO after AAA. The ΔE was more influenced by the composite resin than the LED device.
The knowledge of composite resin with deficiencies in the polymerization mechanism could contribute to preventing restorations to become more susceptible to color change and reduction of the mechanical strength.
本研究旨在评估复合树脂在使用不同发光二极管（LED）光固化并经历人工加速老化（AAA）后的显微硬度和颜色变化（ΔE）。
选择两种含Lucirin-TPO光引发剂的复合树脂：Tetric N-Ceram（义获嘉伟瓦登特公司，A1）和Vit-l-escence（登士柏公司，WO）。选用仅含樟脑醌光引发剂的树脂作为阴性对照：Filtek Z350XT（3M ESPE公司，WD）。制备圆盘形试件（直径5毫米；厚1.5毫米），每种复合树脂（n = 10）分别用单一波长的LED（Radii-Cal，SDI）或多波长的LED（Valo，登士柏公司）进行光聚合。在试件制备后及人工加速老化后立即进行表面显微硬度和颜色评估。使用Kruskal-Wallis检验和Mann-Whitney检验对显微硬度结果进行多重比较分析。为比较不同时间的显微硬度评估结果，使用Wilcoxon检验。使用双向方差分析（ANOVA）评估ΔE、ΔL、Δa和Δb的平均值，并使用Tukey检验进行多重比较（α = 0.05）。
关于显微硬度，人工加速老化后，Vit-l-escence在两种LED之间观察到统计学上的显著差异。当比较用同一设备光固化的复合树脂时，Filtek Z350XT获得的显微硬度最大。所有组从初始时间到人工加速老化后显微硬度均呈现统计学上的显著下降。关于ΔE，在两种LED之间未观察到统计学上的显著差异。当比较复合树脂时，Filtek Z350XT显示出最高的ΔE值。
总体而言，多波长LED仅在人工加速老化后影响了一种含Lucirin-TPO的树脂的显微硬度。ΔE受复合树脂的影响大于LED设备。
了解聚合机制存在缺陷的复合树脂有助于预防修复体更易出现颜色变化和机械强度降低的情况。
