Polymerization shrinkage and polymerization shrinkage stress in polymer-based restoratives

Objectives: This paper is intended to contribute to the recognition and understanding of problems related to polymerization shrinkage. Data sources: Scientific publications of relevance with regard to this subject were critically reviewed. Study selection: The dimensional changes which develop during the curing of resin composites and glass polyalkenoate cements are studied, with special reference to methods of determining shrinkage, shrinkage stress and stress relief. Conclusions: As no method for handling the adhesive restorative materials has yet been described which guarantees a leakproof restoration, the practitioner has to accept the problem of polymerization shrinkage and destructive shrinkage stress. Only a proper understanding of the mechanisms that cause these problems and the techniques that may reduce their effects will enable the practitioner to derive maximum benefit from the application of resin composites and glass polyalkenoate cements in restorative dentistry.