title: Conversion-dependent shrinkage stress and strain in dental resins and composites.
abstract: The placement of dental composites is complicated by the contraction that accompanies polymerization of these materials. The resulting shrinkage stress that develops during cure of a bonded restoration can induce defects within the composite, the tooth or at the interface resulting in compromised clinical performance and/or esthetics. In light of the substantial efforts devoted to understanding and attempting to control shrinkage stress and strain in dental composite restoratives, this paper offers a perspective on the conversion dependent development of shrinkage and stress. The relationships between polymer property development and the physical evolution of the network structures associated with dental polymers as well as the interrelated kinetics of the photopolymerization reaction process are examined here. Some of the methods used to assess conversion in dental resins and composites are considered. In particular, newly introduced techniques that allow real time analysis of conversion by near-infrared spectroscopy to be coupled directly to simultaneous dynamic measurements of either shrinkage stress or strain are described. The results are compared with reports from the dental materials literature as well as complementary studies in other related fields of polymer science. The complex, nonlinear correlation between conversion, shrinkage and stress are highlighted. A brief review of some of the materials-based approaches designed to minimize polymerization shrinkage and stress is also provided.
authors.affiliation: Department of Restorative Dentistry, University of Colorado Health Sciences Center, Aurora, CO 80045-0508, USA. jeffrey.stansbury@uchsc.edu
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Stansbury
authors.forename: Marianela
authors.initials: M
authors.lastname: Trujillo-Lemon
authors.forename: Hui
authors.initials: H
authors.lastname: Lu
authors.forename: Xingzhe
authors.initials: X
authors.lastname: Ding
authors.forename: Yan
authors.initials: Y
authors.lastname: Lin
authors.forename: Junhao
authors.initials: J
authors.lastname: Ge
mesh_terms: D003188:Composite Resins / Q000737:chemistry* / Q000528:radiation effects*; D018772:Dental Marginal Adaptation; D003799:Dental Stress Analysis; D004548:Elasticity; D006244:Hardness; D008027:Light; D008422:Materials Testing; D044367:Phase Transition; D011108:Polymers / Q000737:chemistry; D013055:Spectrophotometry, Infrared; D013314:Stress, Mechanical; D014783:Viscosity
chemical_list: D003188:Composite Resins; D011108:Polymers