Measurement of local deformation fields in dental composites using 3d optical system

Polymerization shrinkage is the single most important local deformation of dental composites that has a substantial effect on the quality of the tooth-restoration interface in clinical conditions. The aim of this study was to investigate the possibility to analyze local deformation fields of a dental composite upon polymerization using the 3D optical method of digital image correlation with two cameras. Conventional, microhybrid composite samples were prepared in custom-made Teflon molds and polymerized with a conventional halogen light. Local deformation fields were determined using the two-camera system, Aramis 2M, by correlating sample dimensions before and after polymerization. The greatest deformations of up to 6 % with the average of 3.5 % were observed along the periphery of the samples in contrast to substantially lower deformations of about 1-1.5% in the central parts. Polymerization of dental composites yields heterogeneous deformation with variations in shrinkage values. The 3D optical system is a promising tool enabling qualitative and quantitative mapping of local deformation fields in dental composites.