title: Influence of curing mode with a LED unit on polymerization contraction kinetics and degree of conversion of dental resin-based materials.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the influence of photopolymerization mode with a light emitting diode (LED) lamp on the curing contraction kinetics and degree of conversion of 3 resin-based restorative materials.
  
  
  METHODS
  The curing contraction kinetics of Admira (ADM), Filtek P60 (P60), and Filtek Flow (FLO) were measured by the glass slide method. The materials were exposed to light from a 1,000 mW/cm-(2) power LED lamp (Elipar Freelight 2) in 3 modes: 2 continuous modes of 20 and 40 seconds (C20 and C40), and 1 exponential mode (E20; 5 seconds of exponential power increase followed by 15 seconds of maximum intensity). The degree of conversion (DC) was measured for each of the materials, and each of the modes by Fourier transformed infra-red spectrometry.
  
  
  RESULTS
  P60 had the significantly lowest final contraction and FLO the highest among all light exposure modes. The C20 and C40 modes did not produce any difference in contraction or degree of conversion. The E20 mode led to a significant slowing of contraction speed combined with greater final contraction.
  
  
  CONCLUSIONS
  Use of a LED lamp (1,000 mW/cm2) in continuous mode reduces the exposure time by half for identical curing shrinkage and degree of conversion.
authors.affiliation: Laboratory of Physics of Materials, Unite Mixte de Recherche, Centre National de Recherche Scientifique, Nancy, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Mortier
authors.forename: Yorick
authors.initials: Y
authors.lastname: Simon
authors.forename: Abdelsellam
authors.initials: A
authors.lastname: Dahoun
authors.forename: David
authors.initials: D
authors.lastname: Gerdolle
mesh_terms: D003188:Composite Resins / Q000737:chemistry*; D055117:Curing Lights, Dental; D003764:Dental Materials / Q000737:chemistry*; D007700:Kinetics; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry*; D012833:Siloxanes / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D003188:Composite Resins; D003764:Dental Materials; C467913:Filtek Flow; C438835:Filtek P60 Composite Resin; D008689:Methacrylates; D012833:Siloxanes; C479084:admira