Light curing and ratio of glass/fumed silica fillers on degree of conversion and mechanical properties of experimental composite resins

Abstract

This study evaluated the degree of conversion and mechanical properties of experimental composite resins made with different fillers and light-curing methods. All composites had the same organic matrix (40% wt) and photoinitiator system (1.2% wt). Experimental composite groups were divided according to ratio (%) of silanated ground glass (0.5 mu m) (BaAlSi) and fumed silica (SiO2): 100/0, 90/10, 80/20, and 70/30. Light-emitting diode light was used in the continuous, soft-start, and pulse-delay modes (n = 10). Degree of conversion was determined using attenuated total reflectance-Fourier transform infrared spectroscopy. Flexural strength and modulus were obtained using a universal testing machine, and Knoop microhardness was measured in a Knoop indenter. The data were subjected to a two-way ANOVA and Tukey's post hoc test (alpha = 0.05). Continuous-light exposure of the 100/0 group produced the highest degrees of conversion. Soft-start exposure of the 70/30 groups produced the highest Knoop microhardness. The pulse-delay method produced the lowest flexural strength and modulus values. The 100/0 and 70/30 groups had the lowest flexural strength and flexural modulus, respectively. Application of continuous-light output with composite resins containing a ratio of 80/20 (BaAlSi/SiO2) fillers generated the best results regarding the degree of conversion and mechanical properties. (c) 2018 Wiley Periodicals, Inc.