How filler properties, filter fraction, sample thickness and light source affect light attenuation in particulate filled resin composites

Objective. It was hypothesized that by standardizing variables such as light sources, filter types and fitter surface treatment, it should be possible to use Beer-Lambert's law to predict light absorption in visible light-cured dental composites. Methods. Mixture of 50 wt% bisGMA and 50 wt% TEGDMA to which a photo-initiator (0.35wt% champhorquinone) and a co-initiator (0.7wt% of dimethylaminoethyl-methacrylate) was prepared. Three different filter types (HBB, SBB and KU) were added to that mixture in eight different volume percentage. Filter particles were either silane surface treated or not. Specimens were made with thicknesses of 1-5 mm. Total number of 1200 specimens were made for this study. Light transmission was obtained for halogen source and laser lights, which made the number of observations 2400. The absorbance values of the different materials were analyzed in Matlab with respect to the differences in filter fraction and sample thickness. Results: The obtained results revealed that of the two light sources, more tight was absorbed by the composite when the laser light was used. Among different filter types, the HBB filter absorbed most light and the KU filter the least. There were significant differences (p < 0.05) in light absorption between all three filter types. Significance. By comparing the modeled surfaces generated by Matlab for different materials it was possible to determine how different variables such as filter type, filter surface treatment and light source affect Light attenuation. The characteristic of incident light affected the Light absorbance, meaning that not only the composite's composition needs to be considered in Light absorption studies of dental composites. (c) 2005 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.