Third 3 Flashcards
What’s translucency ?
Between Opaque and transparent
Human teeth are characterized by varying degrees of translucency.
What’s translucency ?
Between Opaque and transparent
Human teeth are characterized by varying degrees of translucency.
Pieces of frosted glass or snow can have the exact same chroma, hue, and value but not look the same WHY ?
Due to different translucency
Who’s does translucency affect value ?
increasing the translucency of a crown lowers its value because less light returns to your eye.
With increased translucency, light that enters is scattered within the body of porcelain.
Why do we compare the illuminated light to the enamel as a fiber-optic cable ?
When light enters enamel it gets bounced around the enamel like a fiber-optic cable.
If you illuminate one side of a tooth with a curing light, the entire crown is lighted.
Similar to the fiber-optic cable, enamel is an optically dense material bordered on either side by air or dentin, both with significantly lower optical densities.
How does prosthetic crown can be bright and translucent at the same time ?
increasing opacity or reflectivity increases value.
By increasing the optical density of the dental ceramics, the fiber-optic properties of natural enamel can be replicated and the prosthetic crown can be bright and translucent at the same time.
It is with the translucent enamel layer that the ceramist achieves color depth and the illusion of a vital natural tooth.
How does wavelengths affect translucency of enamel ?
In which light enamel is more translucent ?
The longer the wavelength, the higher the translucency.
Therefore, enamel is more translucent in light rich in yellow and red, and will show more dentin making the tooth appear redder with a higher chroma and lower
3 value than it actually is.
What’s Fluorescence ?m where does it occur in natural teeth ?
by defini- tion is the absorption of light by a material and the 4 spontaneous emission of light in a longer wavelength.
Fluorescence in a natural tooth primarily occurs in the dentin due to the higher amount of organic materia
present.
How does UV light affect our teeth appearance ?
UV light can have a dramatic affect on the level of vitality exhibited by our restorations.
With the characteristic of fluorescence, our restorations look brighter and more alive.
So whether the patient is at a disco or at the beach, the crown will look more genuine
Ambient near-UV light is ?
absorbed and then fluoresced back as light primarily in the blue end of the spectrum but it will occur at all wavelengths.
How does chroma level affect fluoresces ?
the lower the chroma —> more the dentin fluoresces
Fluorescence is a subset of what ?
Reflectivity
What’s Fluorescent powders ?
are added to crowns to increase the quantity of light returned back to the viewer, to block discolourations and decrease chroma .
The powder is beneficial to ?
in high-value shades as it can raise value without negatively affecting translucency when placed within the dentin porcelain layers.
The powder is beneficial to ?
in high-value shades as it can raise value without negatively affecting translucency when placed within the dentin porcelain layers.
