Aromaa M K, Lassila L V J, Vallittu P K
Department of Biomaterials Science and Turku Clinical Biomaterials Centre - TCBC, Institute of Dentistry, University of Turku, Turku, Finland.
City of Turku, Welfare Division.
Eur J Prosthodont Restor Dent. 2017 Sep;25(3):131-135. doi: 10.1922/EJPRD_01700Aromaa05.
Light transmittance of dental composites varies between products and shades, but also light curing units differ to each other in their irradiance and fiber optic structure of curing tip. The aim of this study was to investigate whether there is linear relationship between the distance of the curing tip to the resin composite and irradiance at lower surface of the resin composite.
Disks of 1 mm thickness (6mm diameter) were fabricated. Light transmittance (intensity) through the disk was measured at distance of 0, 2, 4, 6, 8, 10 mm from the light tip with two light curing units Elipar S10 (3M-ESPE) and Silverlight (GC). Irradiance ratio (irradiance on the sensor surface without the composite disk / with the composite disk) was calculated and plotted against the distance of the light curing tip. Statistical analysis was carried out using analysis of covariance (ANCOVA, Tukey's, α =0.05).
Irradiance ratio varied between 18% to 24% with Silverlight and 21% to 26% with Elipar S10 light curing units. There were statistically significant differences between the ratios with different distances of the light curing tip (p⟨0.05). Interestingly, the highest irradiance ratio for Elipar S10 unit was found with 4 mm distance of the tip, whereas Silverlight unit had the highest ratio with 6 mm distance. Out of two tested resin composites, the flowable composite showed higher irradiance ratio than regular packable resin composite.
Increase of distance of the light curing tip from the composite surface decreased the absolute irradiance underneath of composite, as expected. However, there seemed to be device dependent optimal distance of 4-6 mm to reach the most efficient irradiance ratio through the composite resin keeping in mind that most efficient transmission of light through the material is reached by having light curing tip in contact to the material.
牙科复合材料的透光率因产品和色度而异，而且光固化机在其辐照度和固化头的光纤结构方面也互不相同。本研究的目的是调查固化头与树脂复合材料之间的距离和树脂复合材料下表面的辐照度之间是否存在线性关系。
制作了厚度为1mm（直径6mm）的圆盘。使用两种光固化机Elipar S10（3M-ESPE）和Silverlight（GC），在距光固化头0、2、4、6、8、10mm的距离处测量透过圆盘的透光率（强度）。计算辐照度比（无复合圆盘时传感器表面的辐照度/有复合圆盘时），并将其与光固化头的距离作图。使用协方差分析（ANCOVA，Tukey检验，α = 0.05）进行统计分析。
Silverlight光固化机的辐照度比在18%至24%之间，Elipar S10光固化机的辐照度比在21%至26%之间。光固化头不同距离下的辐照度比之间存在统计学显著差异（p＜0.05）。有趣的是，Elipar S10光固化机在固化头距离为4mm时辐照度比最高，而Silverlight光固化机在距离为6mm时辐照度比最高。在两种测试的树脂复合材料中，可流动复合材料的辐照度比高于常规可填充树脂复合材料。
正如预期的那样，光固化头与复合材料表面距离的增加会降低复合材料下方的绝对辐照度。然而，考虑到通过使光固化头与材料接触可实现光在材料中的最有效传输，似乎存在与设备相关的最佳距离4 - 6mm，以通过复合树脂达到最有效的辐照度比。
