Finite element analysis of V-shaped tooth defects filled with universal nanohybrid composite using incremental technique

The aim of the present paper is to study the stresses and strains in fillings of V-shaped tooth defects made of universal photo-cured nanohybrid composite (UPC) using incremental technique. Numerical modeling with FEA and microleakage test are performed. Inhomogeneous distribution of the equivalent Von Mises stresses after polymerization of the two UPC layers is found, as the maximal value after polymerization of the first layer is 1.5 times lower compared to that of second one. In the first layer, maximum stresses are concentrated on dentin surface in cervical region of the obturation border and in occlusal region of the obturation volume. In the second layer, maximum stresses are generated in cervical area of the obturation volume and on dentin surface occlusally along the obturation border. The displacement after polymerization of each layer is inhomogeneous, as its values are more than 2 times smaller compared to that in fillings of glass-ionomer cement and flowable composite. In the first layer, the displacement is maximal on surface in the cervical region, while in the second layer it is maximal on surface occlusal of the obturation. The adequacy of the model used is confirmed by the microleakage test results. It is proven that UPC is better choice for filling of V-shaped defects due to the lower microleakage.