Abstract
It is well known that spectral reflectance and transmission differ with various instruments. We proposed that these differences were caused by unhomogeneous distribution of reflective or transmissive light. Three-dimensional spectral reflectance of dental porcelains were measured with a goniophotometer. The spatial distributions of specular and diffuse reflections from dental porcelains were differed along with the porcelain type. The colors of the body, enamel and translucent porcelain were affected by these specular reflections. The specular reflected light on dental porcelains can not be removed with a uniform light trap, because these spatial distributions differed with the porcelain type. These specular reflections could be removed with a 15-degree flap angle. However, spatial distributions of diffuse reflection depend on the wavelength of light, so the color of dental porcelain changes along with view the angle. Accordingly, the determination of color on dental porcelain with diffuse reflection light is yet incomplete, so particulars study is necessary on unhomogeneity of specular and diffuse reflections, and spectral reflectance.
