Degree of conversion and cross-link density within a resin-matrix composite

Afnan O. Al-Zain, George J. Eckert, Henry Lukic, Spiro J. Megremis, Jeffrey Platt

Research output: Contribution to journalArticle

5 Scopus citations


The aims of this study were to profile light radiated from two light-curing units (LCUs) and evaluate profile relationship to polymerization patterns within a resin-matrix composite (RMC). Beam profiles of one multiple emission peak light-emitting-diode and one quartz-tungsten-halogen curing-unit were measured using a beam profiler/spectrometer system. A camera-based profiler and an integrating sphere/spectrometer assembly were used to evaluate each LCU beam. Polymerization patterns within a nano-hybrid RMC were investigated using a mapping approach by assessing the degree of conversion utilizing micro-Raman spectroscopy and indirectly estimating cross-link-density by repeated microhardness testing before and after exposure to ethanol (%KH reduction, n = 3). The irradiance received on the top and bottom specimen surfaces from both LCUs was measured using a MARC-RC system. The investigated beam profile area from both LCUs was non-uniform and yielded localized discrepancies in DC (55.7–74.9%) and %KH reduction (26.7–54.1%). The LCU irradiance received at the bottom of the specimens was ∼10% of the top value. This study demonstrated that LCU beam profiles were non-uniform in the area explored. Localized differences in DC and %KH reduction existed throughout the RMC specimens but did not follow a specific pattern.

Original languageEnglish (US)
Pages (from-to)1496-1504
Number of pages9
JournalJournal of Biomedical Materials Research - Part B Applied Biomaterials
Issue number4
StatePublished - May 1 2018


  • beam profile
  • cross-link density
  • degree of conversion
  • light curing unit
  • resin composite

ASJC Scopus subject areas

  • Biomaterials
  • Biomedical Engineering

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