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Objectives: To investigate the influence of nanoscale inorganic content over optical and surface properties of model composites before and after ageing., Methods: Three model composites were formulated with silica fillers in nanoscale of 7 nm (G1), 12 nm (G2) and 16 nm (G3), at 45.5% by weight in a matrix of BisGMA/TEGDMA 1:1. Color coordinates (CIE L*a*b* parameters), color difference (ΔE*), translucency parameter (TP), surface gloss (SG) and surface roughness (SR) were measured before and after ageing procedures of immersion in water and toothbrush abrasion. Surface hardness (SH) were evaluated before and after immersion in absolute ethanol. Results were submitted to two-way ANOVA followed by Tukey's post hoc test performed at a pre-set alpha of 0.05., Results: Regarding CIE L*a*b* parameters, a darkening, a redness and a blueness effect, were respectively detected after water storage for all groups. Smaller filler sizes (G1) had the highest CIE b* values, whereas medium (G2) (p<0.05) had higher values than larger fillers (G3) (p<0.05) either before or after water immersion. Toothbrush abrasion did not produce any significant effect on CIE a* and CIE b* values, however increased CIE L*, decreased TP in addition to produce rougher and matte surfaces in all groups. Filler size did not influence ΔE* (p>0.05), although a tendency towards lower values in smaller filler materials was observed. Ageing after immersion in absolute ethanol decreased SH for all model composites., Conclusions: Filler sizes and ageing procedures influenced the optical and surface properties of the nanostructured composites evaluated in this study., Clinical Significance: Filler size influenced optical and surface properties of resin composites. Materials containing smaller filler size offered improved optical stability and surface properties that can lead to longer maintenance of the restoration's appearance in the oral environment., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Objectives: The aim of this study was to formulate materials with high color stability and reduced degradation by using photoinitiator systems derived from phosphine oxides alternative to the traditional camphorquinone (CQ)/amine system., Methods: Materials were formulated with the monomers BisGMA and TEGDMA as organic matrix. The photoinitiators tested were CQ+amine (EDMAB), phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (BAPO), BAPO+EDMAB, diphenyl(2,4,6-trimethylbenzoyl)-phosphine oxide (TPO) and TPO+EDMAB. A 60% mass of silanated glass filler particles was added. Degree of CC conversion was evaluated by Fourier-transformed infrared spectroscopy 10min after photopolymerization. The color properties were evaluated by a digital spectrophotometer, applying the CIELab parameters, either before photoactivation, immediately after photoactivation, 24h after dry storage, and one month after water immersion. Water sorption and solubility were assessed by mass gain or loss after storage in water for 30 days. Data were analyzed using ANOVA and Tukey's test (5%)., Results: Degree of conversion did not differ statistically among all the tested formulations. Regarding color, only groups with TPO presented satisfactory color stability after one month of water storage (ΔE<3.3). Water sorption and water stability did not differ among the groups., Conclusions: Degree of conversion, water sorption and water solubility did not differ among all the tested groups. The TPO-based groups were the only materials with satisfactory color stability after one month of water storage., Clinical Significance: The use of a photoinitiator system containing TPO might improve the color stability of resin composites compared with the traditional CQ/amine system while attaining similar physico-chemical properties for the composite., (Copyright © 2012 Elsevier Ltd. All rights reserved.)