On fracture analysis of dental restorative materials under combined tensile-shear loading

Dental resins, which are used in dentistry as restorative materials, are subjected to combined shear and tensile loads during their lifetime. In this paper, mixed-mode fracture behavior of two types of dental resins is studied using different fracture criteria, with special focus on strain-based criteria. It is shown that the traditional fracture criteria, which only take into account singular terms of the crack tip stress/strain fields, are not able to properly predict the fracture test data for these materials. An extended maximum tangential strain criterion considering effect of first nonsingular strain term, as well as the singular strain terms, is then employed to predict the fracture test data. It is demonstrated that the extended maximum tangential strain criterion presents more accurate predictions of the test data than the traditional fracture criteria.