OPTICAL PROPERTIES OF DENTAL BIOCERAMICS EVALUATED BY KUBELKAMUNK MODEL

摘要

Bioceramic prostheses have been widely used in restorative dentistry due to their superior aesthetics. The mechanical properties of bioceramics for dental prosthesis have been studied extensively. However, data regarding their optical properties are scarce, despite the fact that they are necessary for modeling and predicting the light interaction with restorations. The aim of this work was to investigate the optical behavior of bioceramics used for dental restorations by Kubelka-Munk (K-M) model. Samples of a vacuum-sintered porcelain and three ceramic composites (Al_2O_3, Al_2O_3-ZlO_2, MgAl_2O_4) infiltrated with glass were prepared. Reflectance was measured using a spectrophotometer using white and black backgrounds. Scattering (S) and absorption (K) coefficients, determined by K-M model, varied significantly among the investigated materials. In all bioceramics, the value of absorption coefficient decreased strongly with the increase in wavelength, while the value of scattering coefficient increased or remained almost constant. In general, the value of scattering coefficient increased with the decrease in the material's transparency, but this tendency was not observed for the value of absorption coefficient. The optical properties were correlated with the material's microstructure and mean free path for light propagation. The results indicated that the scattering was the dominant mechanism that determined the light transmission in the investigated materials, but, in low wavelength range, the absorption also had a significant effect.