The specific aim is to determine the degree of conversion in cured dental composite resins following polymerization by light using Raman spectroscopy. The ultimate goal is to use Raman spectroscopy as an in situ tool for rapid quantitative monitoring of curing during dental cavity restoration procedures. In the experiment, first dental resins in the monomer form obtained from various manufacturers were cured for various times using conventional visible green light source. Raman spectra of these materials were obtained using 830 nm laser excitation. Raman spectra exibited dramatic differences between uncured and cured composites. While the intensity of aromatic double bonds at 1610 cm-1 remain constant, the aliphatic C=C at 1645 cm-1 decreased as the curing time of the composite varies from 0 secs to 120 secs, indicating polymerization. There is also a concomitant decrease in C-H bending modes in the region near 1400 cm-1 with increase of curing time. It was first demonstrated that laser excitation itself does not induce any polymerization. The plot of the intensity ratio of aliphatic to aromatic C=C bands showed the extent of polymerization or curing at each time. The initial results suggested the potential of Raman in quantitatively monitoring curing of dental resins. The effect of white light versus argon ion laser on degree of curing is under investigation.
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