title: Factors involved in the development of polymerization shrinkage stress in resin-composites: a systematic review.
abstract: OBJECTIVE
  Polymerization shrinkage stress of resin-composite materials may have a negative impact on the clinical performance of bonded restorations. The purpose of this systematic review is to discuss the primary factors involved with polymerization shrinkage stress development.
  
  
  METHODS
  According to the current literature, polymerization stress of resin composites is determined by their volumetric shrinkage, viscoelastic behavior and by restrictions imposed to polymerization shrinkage. Therefore, the material's composition, its degree of conversion and reaction kinetics become aspects of interest, together with the confinement and compliance of the cavity preparation.
  
  
  METHODS
  Information provided in this review was based on original scientific research published in Dental, Chemistry and Biomaterials journals. Textbooks on Chemistry and Dental Materials were also referenced for basic concepts.
  
  
  CONCLUSIONS
  Shrinkage stress development must be considered a multi-factorial phenomenon. Therefore, accessing the specific contribution of volumetric shrinkage, viscoelastic behavior, reaction kinetics and local conditions on stress magnitude seems impractical. Some of the restorative techniques aiming at stress reduction have limited applicability, because their efficiency varies depending upon the materials employed. Due to an intense research activity over the years, the understanding of this matter has increased remarkably, leading to the development of new restorative techniques and materials that may help minimize this problem.
authors.affiliation: Department of Dental Materials, School of Dentistry, University of São Paulo, Av. Prof. Lineu Prestes, 2227, São Paulo, SP 05508-900, Brazil. rrbraga@usp.br
authors.forename: Roberto R
authors.initials: RR
authors.lastname: Braga
authors.forename: Rafael Y
authors.initials: RY
authors.lastname: Ballester
authors.forename: Jack L
authors.initials: JL
authors.lastname: Ferracane
mesh_terms: D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003188:Composite Resins / Q000737:chemistry*; D006801:Humans; D011108:Polymers / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties
chemical_list: D003188:Composite Resins; D011108:Polymers