Abstract:Shrinkage deformation of light cured composite resin is a major cause of the failure of dental restoration. Based on the electronic speckle pattern interferometry method (ESPI), the shrinkage deformation of light cured composite resins (Type R1 and Type R2) are measured under the different conditions. The ESPI patterns are obtained during shrinkage of the Type R1 and Type R2 According to these experimental results, the relative curves of the max out of plane displacement and time are plotted. The results show that the shrinkage deformation of light cured composite resin is connected with the width of the hole in the tooth. When the width increase, the shrinkage deformation increase as well, but there was no linear relation between them. The results also show that Type R1 is more suitable for clinical application.