Color and Optical Properties of Posterior Composites under Accelerated Aging

The color and optical properties of three anterior and four posterior composites were determined from reflection spectrophotometric data and Kubelka's equations. Samples were aged for 300 hours at 43°C, 90% relative humidity, intermittent water spray, and continuous exposure to a 2500 watt xenon light. After aging the composites were generally darker, more chromatic, and more opaque. Values of S (absorption coefficient) and K (scattering coefficient) increased and values of XI (infinite optical thickness) decreased. The light-cured composites were less stable than the chemically cured ones.