Simulation of color perception of layered dental composites using optical properties to evaluate the benefit of esthetic layer preparation technique.

Esthetic restorations require that dental restorative materials have similar optical properties to teeth. To improve the color perception, the inhomogeneous morphology of the native tooth can be imitated by layering two optically different restorative materials. However until now the benefit of this method has not been satisfactorily demonstrated.The optical parameters, absorption coefficient μ(a), scattering coefficient μ(s), anisotropy factor g and effective scattering coefficient μ'(s), were determined for the enamel and dentin material of the restorative material systems Artemis(®) and Herculite XRV(®). This was carried out for each material system in the wavelength range between 400 and 700nm using integrating sphere measurements followed by inverse Monte Carlo simulations.Using the optical parameters and a forward Monte Carlo simulation, the color perception of layered samples could be predicted with a sufficient degree of accuracy. The total color impression was shown to be dependent on the sample thickness and the transparency/translucency of the single layers of enamel and dentin materials.The study demonstrated that the use of two materials is well-suited for the restoration of front teeth with their relatively high proportion of enamel. This study will continue further with the compilation of a data pool of optical parameters which will enable the application of calculation models to optimize the optical approximation of the natural tooth.