title: Polymerization shrinkage and hygroscopic expansion of contemporary posterior resin-based filling materials--a comparative study.
abstract: OBJECTIVE
  To investigate the polymerization shrinkage and hygroscopic expansion of contemporary posterior resin-based filling materials.
  
  
  METHODS
  The densities of SureFil (SU), CeramXMono (CM), Clearfil AP-X (CF), Solitaire 2 (SO), TetricEvoCeram (TE), and Filtek P60 (FT) were measured using the Archimedes' principle prior to and 15min after curing for 20, 40 and 60s and after 1h, 24h, 7 d, and 30 d storage at 37 degrees C in water. Volumetric changes (DeltaV) in percent after polymerization and after each storage period in water were calculated from the changes of densities. Water sorption and solubility were determined after 30 d for all specimens and their curing times. Two-way ANOVA was calculated for shrinkage and repeated measures ANOVA was calculated for hygroscopic expansion (p<0.05).
  
  
  RESULTS
  DeltaV depended on filler load but not on curing time (SU approximately -2.0%, CM approximately -2.6%, CF approximately -2.1%, SO approximately -3.3%, TE approximately -1.7%, FT approximately -1.8%). Hygroscopic expansion depended on water sorption and solubility. Except for SU, all materials showed DeltaV approximately +1% after water storage.
  
  
  CONCLUSIONS
  Polymerization shrinkage depended on the type of resin-based filling material but not on curing time. Shrinkage was not compensated by hygroscopic expansion.
authors.affiliation: Heinrich-Heine-University, Medical Faculty, Centre of Dentistry, Department of Operative and Preventive Dentistry and Endodontics, Moorenstr. 5, Geb. 18.13, D-40225 Düsseldorf, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Rüttermann
authors.forename: Sören
authors.initials: S
authors.lastname: Krüger
authors.forename: Wolfgang H-M
authors.initials: WH
authors.lastname: Raab
authors.forename: Ralf
authors.initials: R
authors.lastname: Janda
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D003188:Composite Resins / Q000737:chemistry*; D008422:Materials Testing / Q000379:methods; D011108:Polymers / Q000737:chemistry; D011140:Polyurethanes / Q000737:chemistry*; D012995:Solubility; D013997:Time Factors; D014867:Water; D017155:Wettability