Color stability of new composite restorative materials under accelerated aging.

The color stability of seven commercial composite restorative materials under conditions of accelerated aging was evaluated by reflection spectrophotometry at baseline and 300, 600, and 900 h. During early aging the composites generally became darker, more chromatic, and more opaque. Changes in color of the conventional composites during aging were influenced by erosion of the resin matrices and exposure of filler particles. Color stability of the microfilled composites under the in vitro conditions tested was better than that of the conventional composites and did not appear to be influenced as much by erosion.