Shrinkage characteristics of light-cured composite resin

Polymerization shrinkage of a light-cured composite resin was studied using artificial cylindrical cavities. To examine the property change as functions of cavity depth and irradiation time, we performed two experiments; micro-Vickers hardness and tensile tests. Then we determined the hardness H _v and modulus E of the resin specimens, and the following results were obtained. The values of H _v and E exhibited the maximum near the irradiation surface and then decreased gradually with the depth and the maximum values increased as the irradiation time increased. To study the property change, we introduced an analytical model and suggested that it can predict all the important features of the property change as functions of the depth and irradiation time.