Raman study of composite resins polymerized by a halogen lamp and an argon laser

Abstract

Raman Spectroscopy was used on the present investigation to monitor the degree of conversion of microparticled composite resin (Z100-3M), polymerized by both the conventional halogen light and the Argon Laser beam. Circular blocks of composite 6mm diameter and 3mm of thickness were used on this study. The tip of the halogen light source ((lambda) = 400-500nm, 478mW/cm<SUP>2</SUP>) or the Argon laser beam ((lambda) = 488nm, 624mW/cm<SUP>2</SUP>) was positioned on the surface of the composite resin and both activated for different irradiation times (5, 10, 20, 30, 40 and 60 seconds). The top surface which was directly irradiated and the non-irradiated (inferior) surface were analyzed immediately after curing by Raman Spectroscopy. The Raman results show systematic changes of the relative intensities between the peaks at 1610 (aromatic C=C stretching mode) and the 1640 cm<SUP>-1</SUP> (methacrylate C=C stretching mode), as a function of irradiation time. The degree of conversion was calculated based on the relative intensity change of these two modes and compared for each light source. The change in the relative intensity shows that Raman Spectroscopy can be used as an effective method to study the degree of conversion of composite resins.