title: Curing shrinkage and volumetric changes of resin-modified glass ionomer restorative materials.
abstract: OBJECTIVE
  The objective of the study was to evaluate initial curing shrinkage and volumetric change during water storage of six resin-modified glass ionomer cements (Dyract, DeTrey Dentsply; Fuji II LC, GC Dental Int.; Ionosit Fil, DMG; VariGlass VLC, DeTrey Dentsply; Vitremer, 3M Dental Products; Photac-Fil, ESPE), a hybrid composite (blend-a-lux, Blendax) and a chemical-cured glass ionomer cement (ChemFil Superior, DeTrey Dentsply).
  
  
  METHODS
  The curing shrinkage was determined 5 min and 24 h after polymerization and mixing, respectively. Volumetric changes were examined after 14 d and 28 d water storage. Curing shrinkage and volumetric changes were evaluated using the hydrostatic principle. In addition, the total water content of the materials was measured after 28 d water storage.
  
  
  RESULTS
  Curing shrinkage of most of the resin-modified glass ionomers was greater than the hybrid composite and the chemical-cured glass ionomer cement. After a 28 d water storage, the resin-modified glass ionomers showed volumetric expansion and the chemical-cured glass ionomer showed volumetric loss. All of the examined glass ionomer materials had a higher total water content than the composite. SIGNIFICANCE. The large curing shrinkage of the resin-modified glass ionomer materials measured in this in vitro study could affect the marginal integrity of glass ionomer restorations.
authors.affiliation: Department of Operative Dentistry, University Clinic of Dentistry, Freiburg, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Attin
authors.forename: W
authors.initials: W
authors.lastname: Buchalla
authors.forename: A M
authors.initials: AM
authors.lastname: Kielbassa
authors.forename: E
authors.initials: E
authors.lastname: Helwig
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D000538:Aluminum Silicates / Q000737:chemistry; D000704:Analysis of Variance; D020770:Compomers; D003188:Composite Resins / Q000737:chemistry*; D004356:Drug Storage; D005899:Glass Ionomer Cements / Q000737:chemistry*; D008027:Light; D008689:Methacrylates / Q000737:chemistry; D012117:Resins, Synthetic / Q000737:chemistry; D017640:Silicates / Q000737:chemistry; D014867:Water
chemical_list: D000180:Acrylic Resins; D000538:Aluminum Silicates; D020770:Compomers; D003188:Composite Resins; C088486:Dyract; C079765:Fuji II LC cement; D005899:Glass Ionomer Cements; C091836:Ionosit; D008689:Methacrylates; C081144:Photac-Fil; D012117:Resins, Synthetic; D017640:Silicates; C081982:VariGlass VLC; C084550:Vitremer; D014867:Water; C039733:Chemfil