Quantum yield of conversion of the photoinitiator camphorquinone

Yin Chu Chen, Jack L. Ferracane, Scott A. Prahl

Research output: Contribution to journalArticle

71 Scopus citations

Abstract

The primary absorber in dental resins is the photoinitiator, which starts the photo polymerization process. We studied the quantum yield of conversion of camphorquinone (CQ), a blue light photoinitiator, in dental resin composites using a LED lamp (3M FreeLight) and a Quartz Tungsten Halogen (QTH) lamp (VIP) as the light curing units at five different irradiances. The molar extinction coefficient, ε469, of CQ was 46 ± 2 cm-1/(mol/L) at 469 nm. The reciprocity of irradiance and exposure time holds for changes of CQ absorption coefficient, that is, irradiance × exposure time (=radiant exposure) = constant. Both LED and QTH lamps yielded the same curing threshold (the radiant exposure when CQ absorption drops to 1/e) and the same quantum yield conversion under different irradiances. In our dental resin formulation (0.7 wt.% CQ with reducing agents 0.35 wt.% dimethylaminoethyl methacrylate (DMAEMA) and 0.05 wt.% butylated hydroxytoluene (BHT)) the quantum yield was measured as 0.07 ± 0.01 CQ conversion per absorbed photon.

Original languageEnglish (US)
Pages (from-to)655-664
Number of pages10
JournalDental Materials
Volume23
Issue number6
DOIs
StatePublished - Jun 1 2007

Keywords

  • Curing threshold
  • Dynamic absorption coefficient
  • Light-activated polymerization
  • Molar extinction coefficient
  • Radiant exposure
  • Reciprocity

ASJC Scopus subject areas

  • Materials Science(all)
  • Dentistry(all)
  • Mechanics of Materials

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