Oper Dent. 2019 Jul/Aug;44(4):365-378. doi: 10.2341/16-242. Epub 2019 Jan 31.
Light activation is an important clinical step for achieving success in restorative procedures. This study evaluated the influence of beam profile from different light emission tip types of multiwave light-emitting diodes (LEDs) on the curing profile of resin-based composites. Experimental composites were produced containing either camphorquinone (CQ) or diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO) as a photoinitiator. Multiwave LEDs with either a bundle light guide tip (Bluephase G2, Ivoclar Vivadent) or a microlens tip (VALO Cordless, Ultradent) were characterized using a beam profiler. Block-shaped samples (5×5×3 mm depth) of the two composites were cured in a custom-designed mold with the multiwave LEDs positioned to compare the regions exposed to the 420-495 nm (blue) and 380-420 nm (violet) emittances. To map the curing profile, the degree of conversion (DC) of longitudinal thin cross sections from each block was evaluated using transmission FT-NIR. Radiant exposure transmitted through the composites during curing was evaluated at different thicknesses. Data were analyzed using analysis of variance and Tukey test (α=0.05; β=0.2). The results indicated that there were differences in the beam profile and the overall radiant exposures transmitted through the composites using each multiwave LED (<0.01, =1 =73.18). However, there were no differences in the curing profiles provided by the two multiwave LEDs (=0.89, =12 =0.52), and similar effects were found according to the different LED emittance regions (=0.09, =5, =2.11). When considering up to 1 mm in depth, no differences in the DC were found between the composites containing either photoinitiators. Starting at 2 mm in depth, the composite containing TPO showed a decrease in DC in the 420-495 nm emittance region, while the composite containing CQ showed a similar decrease in cure efficiency only at 3-mm depth under both 380-420 nm and 420-495 nm emittance regions. Thus, despite the fact that the nonuniform light beam emitted from the two multiwave LEDs was visually distinctly different when delivering 24 J/cm, this difference did not seem to affect the curing profile of the composites. However, light transmission within 380-420 nm seems to be reduced with depth, directly affecting the curing profile of composites containing a photoinitiator with absorbance falling within this emission range.
光激活是修复程序成功的重要临床步骤。本研究评估了多波长发光二极管（LED）不同发光尖端类型的光束分布对树脂基复合材料固化性能的影响。实验性复合材料中含有樟脑醌（CQ）或二苯基（2,4,6-三甲基苯甲酰）氧化膦（TPO）作为光引发剂。使用光束轮廓仪对具有束状导光尖端（Bluephase G2，义获嘉伟瓦登特）或微透镜尖端（VALO Cordless，优锐）的多波长 LED 进行了特性描述。将两种复合材料的块状样本（5×5×3mm 深度）在定制模具中固化，将多波长 LED 放置在可比较暴露于 420-495nm（蓝色）和 380-420nm（紫色）发射的区域。为了绘制固化曲线，使用传输式傅里叶变换近红外（FT-NIR）评估每个块体的纵向薄横截面的转化率（DC）。在固化过程中，通过复合材料传输的辐射暴露量在不同厚度下进行评估。使用方差分析和 Tukey 检验（α=0.05；β=0.2）对数据进行分析。结果表明，使用每种多波长 LED 时，光束分布和通过复合材料传输的整体辐射暴露量存在差异（<0.01，=1 =73.18）。然而，两种多波长 LED 提供的固化曲线没有差异（=0.89，=12 =0.52），根据不同的 LED 发射区域也发现了相似的效果（=0.09，=5，=2.11）。在考虑深度达 1mm 时，两种光引发剂的复合材料之间的 DC 没有差异。在 420-495nm 发射区域，深度为 2mm 时，含有 TPO 的复合材料的 DC 降低，而含有 CQ 的复合材料仅在 380-420nm 和 420-495nm 发射区域深度为 3mm 时，固化效率也出现类似降低。因此，尽管从两个多波长 LED 发射的非均匀光束在输送 24J/cm 时在视觉上明显不同，但这种差异似乎并没有影响复合材料的固化曲线。然而，在 380-420nm 范围内的光传输似乎随着深度的增加而降低，这直接影响到吸收落在该发射范围内的光引发剂的复合材料的固化曲线。
