BULETINUL INSTITUTULUI POLITEHNIC DIN IAŞI

52 Irina Grădinaru et al.
from these findings, to the color characterization and transmission in dental
laboratory is a long and difficult way .
This paper presents a synthesis of data from the literature concerning
color which, together with translucency, gloss and fluorescence, contributes to
the aesthetic qualities of dental restorations.
The color of a natural dental structure is influenced by the thickness of
the enamel and the color of the subjacent dentin. Similar considerations can be
applied to dental restorations with layered structure (eg porcelain restorations
which are composed of body porcelain over inner opaque porcelain and resin
composites over more opaque resins). In case of these layered structures, diffuse
reflectance and the relationship between the translucency and thickness of the
outer layer and the color and reflectance of the inner layer represent challenges
to esthetic concerns (Fig.1). The outer translucent layer acts as a light-scattering
filter over the inner layer. As the thickness of the outer layer increases, the
effect of the inner layer is diminished. Similar situations exist when the
translucency of the outer layer decreases (Bratu, 1994; O’Brien, 2008).
Fig.1 – Porcelain–fused-to-metal indirect restoration: optical considerations
after O’Brien.
Color is considered a subjective phenomenon which can be regarded
differently by different observers.
Color may be produced in several different ways, including: selective
reflection, selective absorption, diffraction, scattering, interference.
The color of an object or a dental material result from a number of factors
including: the composition of the material, its thickness, the surface
roughness; the nature of illuminating light (McCabe & Walls, 2008).
The translucency of an object represents the amount of the incident light
transmitted and scattered by the respective object. A color which has a high