Dental restorative materials experience different combinations of tensile and shear loads. In this paper, the fracture initiation is studied under mixed-mode loading for two types of dental resins. A significant discrepancy is shown to exist between the test data reported for these materials and the theoretical results. A generalized maximum tangential stress criterion is then used for fracture analysis of the tested dental resins. The generalized criterion provides considerably improved estimates for fracture resistance of the tested materials.