The influence of stratification on color and appearance of resin composites

The aim of this in vitro study was to determine the influence of the order of composite layers' stratification on resin composites color and appearance when restoring an anterior composite tooth on the 3D color coordinates L*a*b* by use of a spectrophotometer. A total of 192 discs samples made of two different commercial available composite materials (Miris 2 and HRI) of enamel (E) and dentin (D) shade, each with a 1 mm thickness, were divided into 6 configurations. The superposition of 4 samples for a total of 16 specimens per group determined the investigated configurations. All groups showed significant (p < 0.05) differences between them except groups E1DDE and EDDE1 which represent the same order of stratification, measured from the buccal side and from the palatal side. Perceptible differences were detected between all groups except for E1DDE, EDDE1 and EDDD, independent of the background (white or black). The realization of the palatal layer with dentin composite shade did not change the final outcome within the limit of a total 4 mm thickness in comparison to the palatal layer with enamel composite shade.