Detection of leached moieties from dental composites in fluids simulating food and saliva

The purpose of this study was to analyze the IR spectra of a liquid simulating food and an artificial saliva following exposure to resin composites. Fourier transform infrared (FTIR) spectroscopy was used to analyze two solutions in which three commercially available dental composites (Marathon One, Den-Mat Co.; Z100, 3M Co.; Herculite XRV, Kerr Co.) were stored. The solutions used were: a food simulating fluid, 75 vol% ethanol/water, and an artificial saliva, Moi-Stir (Kingwood Labs., Inc.). Specimens (4.3 mm diam. X 2 mm thick) of the three resin composites were stored at 37 degrees C in 60 mL of either Moi-Stir or the 75% ethanol solution for 7, 14, and 30 d. The FTIR spectra were obtained using a liquid sample ATR (attenuated total reflection) cell. No obvious leachable materials were seen from any of the composite specimens stored in artificial saliva up to 30 d of immersion. For the composites stored in ethanol, the observed spectra revealed increases in the principal absorption bands for the components of the three composite systems. Methacrylate skeletal vibrations (1015-815 cm(-1)) and -CH3 alkane, C-H asymmetrical deformation vibrations (1520-1460 cm(-1)) appeared after 14 d of storage. A very strong peak characteristic of the aliphatic C=C moiety (1640 cm(-1)) and carbonyl C=O (1730 cm(-1)) occurred after 14 d. The peak heights of these two functional bands increased as a function of time and after 30 d of storage were approximately 5-7 times those produced after 7 d. Irregular O-H bands (3500-3300 cm(-1)) were also observed after 30 d in ethanol. Irreversible processes such as the leaching of components occurs in the presence of ethanol. This phenomenon may contribute to irreversible material degradation.