GC EUROPE GRADIA Direct (X) - Manual (Page 4)

4
Perfect translucency and
opalescence
gc gradia direct
Optical properties determine
the ‘look’
of a
natural tooth
Colour is the optical property which contributes most to
the appearance of a tooth.
It is actually a three-dimensional space composed of:
• hue - the pure colour itself
• chroma - the saturation of the colour
• value - the lightness or darkness of the colour
In dentistry, the nature of tooth structure also brings into
play other optical properties, such as translucency,
opalescence and fluorescence.
How these optical properties are perceived and hence the
tooth’s appearance, is determined by the way the tooth
reflects light back into the viewer’s eye. There are two
types of reflection:
• Mirror reflection is when all wavelengths are reflected
back to the eye.
• Diffuse reflection occurs when light within the tooth is
reflected off the complex series of interfaces and this
type of reflection is responsible for how the tooth's hue,
chroma and value are actually perceived as well as its
translucency and opalescence.