Heat curing behavior of light-cured composite resins investigated by dynamic differential scanning calorimetry.

The heat curing behavior of light-cured restorative composite resins, light-cured crown and bridge veneering resins, pure dimethacrylate monomers, Bis-GMA monomers containing various initiators, and monomer mixtures were investigated by slow heating at a constant rate with differential scanning calorimetry (DSC) without any light irradiation--the so-called dynamic DSC measurement. Some of the light-cured restorative composite resins and the light-cured crown and bridge veneering resins showed a sharp exothermic peak due to heat curing. Pure TEDMA also showed a sharp exothermic peak, whereas the Bis-GMA monomers containing catalysts for light curing showed no exothermic peak. It seems that heat curing behavior of light-cured composite resins depends not on the decomposition of camphorquinone, but on that of the monomer itself.