The influence of postcuring on the fracture properties of photo-cured dimethacrylate based dental composite resin.

The dependence of the fracture behavior of photocured dimethacrylate-based composite resins on the matrix crosslink density (varied by postcuring at various temperatures) was investigated. In general, the fracture toughness (KIc) was increased by postcuring as has been observed for epoxy-amine networks. The flexural and diametral tensile strength was also raised by postcuring. Calculation of the inherent flaw size (ao) from these properties produced conflicting dependencies on the state of cure. It is suggested that improved wear resistance and incisal edge strength of dental composite resin restoratives may be achieved by increased degree of cure.