Quantum yield of conversion of the photoinitiator camphorquinone

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

Research output: Contribution to journalArticlepeer-review

85 Scopus citations


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
Issue number6
StatePublished - Jun 2007


  • 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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