title: Degree of conversion of resin-based materials cured with dual-peak or single-peak LED light-curing units.
abstract: BACKGROUND
  There is a lack of data on polymerization of resin-based materials (RBMs) used in paediatric dentistry, using dual-peak light-emitting diode (LED) light-curing units (LCUs).
  
  
  OBJECTIVE
  To evaluate the degree of conversion (DC) of RBMs cured with dual-peak or single-peak LED LCUs.
  
  
  METHODS
  Samples of Vit-l-escence (Ultradent) and Herculite XRV Ultra (Kerr) and fissure sealants Delton Clear and Delton Opaque (Dentsply) were prepared (n = 3 per group) and cured with either one of two dual-peak LCUs (bluephase(®) G2; Ivoclar Vivadent or Valo; Ultradent) or a single-peak (bluephase(®) ; Ivoclar Vivadent). High-performance liquid chromatography and nuclear magnetic resonance spectroscopy were used to confirm the presence or absence of initiators other than camphorquinone. The DC was determined using micro-Raman spectroscopy. Data were analysed using general linear model anova; α = 0.05.
  
  
  RESULTS
  With Herculite XRV Ultra, the single-peak LCU gave higher DC values than either of the two dual-peak LCUs (P < 0.05). Both fissure sealants showed higher DC compared with the two RBMs (P < 0.05); the DC at the bottom of the clear sealant was greater than the opaque sealant, (P < 0.05). 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Lucirin(®) TPO) was found only in Vit-l-escence.
  
  
  CONCLUSIONS
  Dual-peak LED LCUs may not be best suited for curing non-Lucirin(®) TPO-containing materials. A clear sealant showed a better cure throughout the material and may be more appropriate than opaque versions in deep fissures.
authors.affiliation: Department of Paediatric Dentistry, Edinburgh Dental Institute, Edinburgh, UK.
authors.forename: Siobhan M
authors.initials: SM
authors.lastname: Lucey
authors.forename: Ario
authors.initials: A
authors.lastname: Santini
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Roebuck
mesh_terms: D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D003188:Composite Resins / Q000737:chemistry*; D055117:Curing Lights, Dental; D055115:Light-Curing of Dental Adhesives / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy; D008422:Materials Testing; D058105:Polymerization; D019279:Resin Cements / Q000737:chemistry*
chemical_list: D003188:Composite Resins; D019279:Resin Cements; C515948:Vit-l-escence Trans Ice; C065770:Herculite XR; D017438:Bisphenol A-Glycidyl Methacrylate