Strategies to overcome polymerization shrinkage--materials and techniques. A review.

UNLABELLED: Stress generation at tissue/resin composite interfaces is one of the important reasons for failure of resin-based composite (RBC) restorations owing to the inherent property of polymerization shrinkage. Unrelieved stresses can weaken the bond between the tooth structure and the restoration, eventually producing a gap at the restoration margins. This can lead to postoperative sensitivity, secondary caries, fracture of the restorations, marginal deterioration and discoloration. As polymerization shrinkage cannot be eliminated completely, various techniques and protocols have been suggested in the manipulation of, and restorative procedures for, RBCs to minimize the shrinkage and associated stresses. Introduction of various newer monomer systems (siloranes) may also overcome this problem of shrinkage stress. This review emphasizes the various material science advances and techniques advocated that are currently available or under trial/testing phase to deal with polymerization shrinkage in a clinical environment. CLINICAL RELEVANCE: Minimizing the shrinkage stresses in RBC restorations may lead to improvement in the success rate and survival of restorations. Thus, it is important for dental practitioners to be aware of various techniques and materials available to reduce these shrinkage stresses and be updated with the current knowledge available to deal with this issue.