Techniques of shrinkage stress reduction in dental restorations

Shrinkage stresses are one of the major problems in dental restoration practice. New techniques of stresses reduction at the restoration-tooth interface are proposed. The propositions are tested for bonded inlays restorations using finite element analysis based on the ABAQUS program. Mechanical properties of photo-cured material, as well as, dentin, enamel and pulp are based on data given in the literature. Two kinds of restorations are taken into account: class I and class II. The paper consists of two parts. At first, polymerization shrinkage for restoration made by classical incremental technique is investigated. Here, a corresponding Huber-Mises’ stress distributions in the whole tooth and two classes of restorations are presented. Next, two methods of stress reduction based on a selective light curing of restoration are investigated. Both methods provide significant reduction of the Huber-Mises stresses in restoration and tooth tissue, especially in the class I restorations.