DETERMINATION OF THE DEGREE OF CURE OF DENTAL RESINS USING RAMAN AND FT-RAMAN SPECTROSCOPY

FT-IR spectroscopy has traditionally been used to determine the degree of conversion of dental resins. FT-Raman scattering provided an alter nate method of obtaining degrees of conversion for these systems and w as particularly useful for measuring spectra of materials without any sample preparation. Raman and FT-Raman spectroscopy gave identical res ults, but the latter technique was preferred for the highly fluorescen t samples often encountered in commercial composites. Linear calibrati on curves were obtained for the aromatic mixtures Bis-GMA/TEGDMA and B isphenol-A/TEGDMA using C=C/Phi, and for the wholly aliphatic mixture EGDMA/EGDA using C=C/C=O, over a wide range of mole ratios. If both th e mole and intensity ratios {C=C/Phi or C=C/C=O} were known for an unc ured dental resin, then the degrees of conversion could be obtained fo r the cured materials using Raman spectroscopy. However, if the mole r atios for the uncured resin were un known, then the degree of conversi on depended on the calibration curve, since the Raman scattering cross section of the vibrational modes depended on the molecules to which t hey were attached.