Relative merits of narrow versus standard diameter light guides

The purpose of this study was to assess the relative effectiveness of narrow versus standard diameter light guides at curing the initial increment of composite in a deep cavity. The micro-hardness of 2 mm thick samples of a light activated microfilled posterior composite was determined. Composite was irradiated at 0, 1 or 6 mm light guide tip/composite surface distances. Light intensity was measured with a computer-based radiometer. Lower surface cure was reduced with increasing light guide tip distances. Narrow diameter guides offered no advantage over standard guides for polymerisation of the initial increment of composite in the base of a cavity.