The polymerization shrinkage of a light cure composite resin, a dental restoration material, was studied using X-ray CT images and a digital image correlation method. An artificial cylindrical cavity in a bovine tooth was filled with the resin after spreading a bonding agent. The two CT images were recorded before and after irradiation of visible-light. The shrinkage behavior was evaluated from the two images by matching them at the bottom of the cavity floor. The result showed that a large deformation was caused on the top free surface of the cavity, suggesting that this surface deformation can decrease the contraction stress around the interface between the resin and tooth structure. The inhomogeneous shrinkage behavior was also observed from the internal displacement and strain fields of the resin.
