Chuang Shu-Fen, Liao Chu-Chun, Lin Jui-Che, Chou Yu-Cheng, Lee Tsung-Lin, Lai Ting-Wen
School of Dentistry and Institute of Oral Medicine, National Cheng Kung University, No.1 Universal Road, Tainan 70101, Taiwan.
Department of Stomatology, National Cheng Kung University Hospital, 138 ShengLi Road, Tainan 70403, Taiwan.
Polymers (Basel). 2021 Dec 9;13(24):4304. doi: 10.3390/polym13244304.
Blue light (BL) curing on dental resin composites results in gradient polymerization. By incorporating upconversion phosphors (UP) in resin composites, near-infrared (NIR) irradiation may activate internal blue emission and a polymerization reaction. This study was aimed to evaluate the competency of the NIR-to-BL upconversion luminance in polymerizing dental composites and to assess the appropriate UP content and curing protocol. NaYF (Yb/Tm co-doped) powder exhibiting 476-nm blue emission under 980-nm NIR was adapted and ball-milled for 4-8 h to obtain different particles. The bare particles were assessed for their emission intensities, and also added into a base composite Z100 (3M EPSE) to evaluate their ability in enhancing polymerization under NIR irradiation. Experimental composites were prepared by dispensing the selected powder and Z100 at different ratios (0, 5, 10 wt% UP). These composites were irradiated under different protocols (BL, NIR, or their combinations), and the microhardness at the irradiated surface and different depths were determined. The results showed that unground UP (d50 = 1.9 μm) exhibited the highest luminescence, while the incorporation of 0.4-μm particles obtained the highest microhardness. The combined 20-s BL and 20-120-s NIR significantly increased the microhardness on the surface and internal depths compared to BL correspondents. The 5% UP effectively enhanced the microhardness under 80-s NIR irradiation but was surpassed by 10% UP with longer NIR irradiation. The combined BL-NIR curing could be an effective approach to polymerize dental composites, while the intensity of upconversion luminescence was related to specific UP particle size and content. Incorporation of 5-10% UP facilitates NIR upconversion polymerization on dental composites.
蓝光（BL）固化牙科树脂复合材料会导致梯度聚合。通过在树脂复合材料中掺入上转换荧光粉（UP），近红外（NIR）照射可激活内部蓝光发射并引发聚合反应。本研究旨在评估近红外到蓝光的上转换发光在聚合牙科复合材料方面的能力，并评估合适的UP含量和固化方案。选用了在980 nm近红外光下呈现476 nm蓝光发射的NaYF（Yb/Tm共掺杂）粉末，并进行4 - 8小时的球磨以获得不同粒径的颗粒。对未处理的颗粒评估其发射强度，并将其添加到基础复合材料Z100（3M EPSE）中，以评估它们在近红外照射下增强聚合的能力。通过以不同比例（0、5、10 wt% UP）混合所选粉末和Z100制备实验复合材料。这些复合材料在不同方案（蓝光、近红外或它们的组合）下进行照射，并测定照射表面和不同深度处的显微硬度。结果表明，未研磨的UP（d50 = 1.9 μm）发光最强，而掺入0.4 - μm粒径的颗粒时显微硬度最高。与单纯蓝光照射相比，20秒蓝光和20 - 120秒近红外光联合照射显著提高了表面和内部深度的显微硬度。5%的UP在80秒近红外照射下有效提高了显微硬度，但在更长时间近红外照射时，10%的UP效果更佳。蓝光 - 近红外联合固化可能是聚合牙科复合材料的有效方法，而上转换发光强度与特定的UP粒径和含量有关。掺入5 - 10%的UP有助于牙科复合材料的近红外上转换聚合。
