Translucency, opalescence and light transmission characteristics of light-cured resin composites

ObjectivesTo evaluate the translucency, opalescence and light transmission characteristics of resin composites with different thicknesses.MethodsDisks of three resin composites (Estelite∑, Beautifil II, Clearfil Majesty) of A2 shade were prepared in diameter of 10 mm with various thicknesses (0.5 mm, 1.0 mm and 2.0 mm). Color was measured according to CIELAB color scale on a reflection spectrophotometer and a color haze meter, and translucency parameter (TP) and opalescence parameter (OP) were calculated. Using the distribution graphs of transmitted light intensity on a goniophotometer, diffusion factor (DF) as an indicator for a diffuse transmission property and peak gain (G0) for a straight-line transmission property were calculated.ResultsThe TP and G0 values significantly decreased in the order: 0.5 mm > 1.0 mm > 2.0 mm thickness (p < 0.05). The OP value increased as the thickness of resin composite increased from 1.0 mm to 2.0 mm (p < 0.05), while was similar for the 0.5 mm- and 1.0 mm-thick groups. The DF value increased from 0.5 mm to 1.0 mm, but was similar for the 1.0 mm- and 2.0 mm-thick groups. There was a significant correlation between TP and DF (R2 = 0.96, p < 0.001). On the other hand, there was a weak correlation between OP and DF (R2 = 0.21, p < 0.005), however within the values of the 0.5 mm-thick group, OP was highly correlated with DF (R2 = 0.84, p < 0.001).SignificanceAt the 0.5 mm thickness, the translucency (TP) and opalescence (OP) of resin composites had a significant correlation with a diffuse transmission property (DF). When more than 1.0 mm thickness of resin composites, translucency and opalescence were influenced by the thickness, in which translucency significantly decreased and opalescence significantly increased.