Objectives: The purpose of this study was to investigate the effect of prolonged chemical challenges on color stability and staining susceptibility of a silorane-based composite material when compared to methacrylate-based composites.
Methods: Cylindrical specimens (n=24) were fabricated from methacrylate (Filtek Z250, 3M ESPE; Filtek Z350XT, 3M ESPE; Master Fill, Biodinâmica) or silorane-based (Filtek P90, 3M ESPE) composite materials. Initial color was registered in a spectrophotometer. Specimens were divided in four groups and individually stored at 37°C in 0.02N citric acid, 0.02N phosphoric acid, 75% ethanol or distilled water (control) for 7, 14, 21, and 180 days, when new measurements were performed. A staining test was performed (n=12) after 21 days of chemical challenge by immersion in coffee during 3 weeks at 37°C. Color changes (¿E) were characterized using the CIEL*a*b* color system. Data were submitted to two-way analysis of variance or analysis of variance for repeated measures, and Tukey’s multiple comparison test (a= 0.05).

Results: Although significantly different (p<0.05), color changes on the methacrylate-based resins and the silorane-based material were not visually perceptible after immersion in water, citric acid, phosphoric acid or ethanol up to 21 days (¿E<3.3). After 180 days of immersion, color change was similar (¿E<3.3) amongst all investigated materials, except for the silorane when immersed in ethanol, which demonstrated visible color change (¿E=4.1±1.3). The methacrylate-based resins stored in ethanol were significantly (p<0.05) more stained by coffee (Filtek Z250 ¿E=24.1±1.1; Filtek Z350XT ¿E=24.0±2.9; Master Fill ¿E=12.8±0.6) than the ones stored in other media, while the silorane-based material demonstrated no staining (Filtek P90 ¿E=2.0±0.6), regardless of the immersion medium (p<0.05).

Conclusions: Ethanol influenced color stability of the silorane-based material and increased the staining susceptibility of the methacrylate-based resins. Storage in phosphoric acid or citric acid did not influence the color stability or staining susceptibility of the investigated materials.

This abstract is based on research that was funded entirely or partially by an outside source: North of Paraná University and private funds supported this study. Authors acknowledge the donation of the investigated materials by 3M ESPE and Biodinâmica