Dental composite restorative materials consist of an organic matrix, ceramic fillers, and the interface between the inorganic fillers and the matrix. Marked variations in the composition of the composite materials, as well as different degrees of conversion after polymerization, have been observed. These circumstances lead to substantial differences in the properties of polymerized composite materials. The variations in clinical behavior of the different composite materials, e.g., discoloration or lack of wear resistance, may be explained on the basis of differences in composition. This review paper describes the composition, conversion, and properties of presently available composite materials

Composites — Characterization of composite filling materials: reactor response.
Ruyter IE.