Luster Flashcards
Give an example about reducing the luster
Lets imagine , piece of clear window glass by wet sanding or etching will produce a frosty white look.
As light hits the surface of the etched glass, it scatters or bends irregularly. This scattering of the light at the surface causes an increase in opacity.
The light isn’t carried off and away from the surface but rather reflected.
As the glass becomes less translu-cent, the value goes up.
The net effect is more light returns to the viewer as the luster goes down.
What’s determines specular reflection?
surface texture and not luster
See the card of value
Although the surface luster has been roughened the glass remains flat and has low texture so it will ?
remain a specular reflector.
How polishing affect restoration appearance ? And why super polish appears bright ?
Polishing the rough glaze off of a porcelain restoration is a subtle way to lower value by making the porcelain clearer and more translucent.
Super polished surfaces can appear bright due to the specular reflection but they are also more translucent because the light isn’t scattered or bent at the surface.
How A heavy surface texture affect value ? And high luster ?
will produce a lower value by redirecting reflections away from the viewer or with double inward reflections, and a high surface luster also makes a tooth or crown darker and more translucent.
Due to the impact they have on the optical properties of the tooth, the wise practitioner will note them in their lab prescription.
Translucent means ?
Light not scattered or bent at the surface
Less translucent = light reflection = value
Why heavy texture decrease value ?
Value =opacity
Heavy cause , tend to diffuse light by reflecting it many directions and less light return to the viewer , less light return = low value
More light return = high value
Low texture = reflection in few or one direction = more light return = high value
It’s why the most of bright restorations with minimal texture
