title: Does layering minimize shrinkage stresses in composite restorations?
abstract: Polymerization shrinkage of resin composites may impair restoration longevity. It is hypothesized that layering, rather than bulk, techniques result in less stress in the tooth-restoration complex. The aim of this study was to compare shrinkage stresses for different restorative techniques used for cusp-replacing restorations with direct resin composite. In a 3-D FE model, the dynamic process of shrinkage during polymerization was simulated. Time-dependent parameters (shrinkage, apparent viscosity, Young's modulus, Poisson ratio, and resulting creep), which change during the polymerization process, were implemented. Six different restorative procedures were simulated: a chemically cured bulk technique, a light-cured bulk technique, and 4 light-cured layering techniques. When polymerization shrinkage is considered, a chemically cured composite shows the least resulting stress. The differences seen among various layering build-up techniques were smaller than expected. The results indicate that the stress-bearing locations are the interface and the cervical part of the remaining cusp.
authors: (PCT 117) Department of Preventive and Community Dentistry and Pedodontology, University Medical Centre Nijmegen, PO Box 9101, 6500 HB Nijmegen, The Netherlands. R.Kuijs@dent.umcn.nl
authors: R H
authors: RH
authors: Kuijs
authors: W M M
authors: WM
authors: Fennis
authors: C M
authors: CM
authors: Kreulen
authors: M
authors: M
authors: Barink
authors: N
authors: N
authors: Verdonschot
mesh_terms: D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003188:Composite Resins / Q000737:chemistry*; D003198:Computer Simulation; D003737:Dental Cavity Preparation; D003743:Dental Enamel / Q000502:physiology; D003793:Dental Restoration, Permanent / Q000379:methods*; D004548:Elasticity; D020342:Finite Element Analysis; D006801:Humans; D008422:Materials Testing; D008954:Models, Biological; D011108:Polymers / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D019237:Tooth Cervix / Q000502:physiology; D014783:Viscosity
chemical_list: D003188:Composite Resins; D011108:Polymers