Optical behavior of one-shaded resin-based composites

•One-shaded resin-based composites show lower spectral scattering and absorbance than the group-shaded resin-based composite.•One-shaded resin-based composites present higher spectral transmittance than the group-shaded resin-based composite.•One-shaded resin-based composites are more translucent than the group-shaded resin-based composite.•Value of opalescence parameter and the effect of thickness on opalescence are material-dependents. To evaluate optical properties, and translucency and opalescence parameters of one-shaded resin-based composites. Three one-shaded resin composites (OM — Omnichroma; VP — Venus Pearl; and VD — Venus Diamond) and a group-shaded resin composite (FU- Filtek Universal A2) were used. Three composite discs from each material were fabricated for each of the following thickness: 0.5, 1.0 and 2.0 mm. Diffuse reflectance was measured against white and black backgrounds using a calibrated spectroradiometer, CIE D65 illuminant and the CIE 45°/0° geometry. Translucency parameter (TP) was calculated using ΔEab * and ΔE00. Scattering (S) and absorption (K) coefficients and transmittance (T%) were calculated using Kubelka–Munk’s equations, and a reflection spectrophotometer was used to measure the opalescence parameter (OP). Data was statistically analyzed using Kruskal–Wallis, Mann–Whitney tests, and VAF coefficient. Spectral distributions of S, K and T were wavelength dependent, showing significant differences between materials of the same thickness and for different thicknesses of the same material (p < 0.001). OM showed the greatest translucency values for all thicknesses. Translucency decreased as thickness increased with statistically significant differences (p < 0.005). Values of ΔTPab and ΔTP00 between thicknesses were above of translucency thresholds for all materials. VP and VD showed the lowest OP values. One-shaded resin-based composites showed different optical behavior than the group-shaded resin-based composite. Understanding the optical behavior of the one-shaded resin-based composites is essential to optimize their clinical performance.