Department of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, ETH Zurich, 8093 Zurich, Switzerland.
Dent Mater. 2012 Mar;28(3):304-11. doi: 10.1016/j.dental.2011.11.018. Epub 2012 Jan 28.
Light-curable polymers are commonly used in restorative surgery, prosthodontics and surgical procedures. Despite the fact of wide application, there are clinical problems due to limitations of blue light penetration: application is restricted to defects exposed to the light source, layered filling of defect is required.
Combining photo-activation and up conversion allows efficient polymer hardening by deep penetrating near-infrared (NIR) light. The prerequisite 450 nm blue light to polymerize dental resins could be achieved by filler particles, which absorb the incident NIR irradiation and convert it into visible light.
The on spot generated blue light results in uniform polymer hardening. Composite samples of 5mm thickness were cured two times faster than pure polymer cured by blue light (30 and 60 s, respectively). Overall degree of monomer conversion resulted in higher values of more than 40%. The enhanced transmission of NIR light was confirmed by optical analysis of dentin and enamel. The NIR transmittance surge in the 800-1200 nm window could improve sealing of complex and deep caries lesions.
We demonstrate faster curing and an improved degree of polymerization by using upconversion filler particles as multiple light emission centers. This study represents an alternative approach in curing dental resins by NIR source.
光固化聚合物在修复外科、修复学和外科手术中被广泛应用。尽管应用广泛，但由于蓝光穿透的局限性，仍存在临床问题：应用仅限于暴露于光源的缺陷，需要分层填充缺陷。
光激发和上转换相结合，可以通过深穿透近红外（NIR）光实现高效聚合物固化。填充颗粒可以吸收入射的 NIR 辐射并将其转化为可见光，从而实现聚合牙科树脂所需的 450nm 蓝光。
现场产生的蓝光可实现均匀的聚合物固化。5mm 厚的复合材料样品的固化速度比纯聚合物（分别为 30s 和 60s）快两倍。单体转化率总体上达到了 40%以上。通过对牙本质和牙釉质的光学分析证实了 NIR 光的增强传输。800-1200nm 窗口中 NIR 透射率的跃升可以改善复杂和深龋病的密封。
我们通过使用上转换填充颗粒作为多个光发射中心，证明了更快的固化速度和更高的聚合度。这项研究代表了一种通过近红外光源固化牙科树脂的替代方法。
