14
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CERECDOCTORS.COM
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QUARTER 3
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2015
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E D E L S O N
The frit colors are liquefied by the SIL shade indexing liquid
which enables the clinician to see the final shaded appear-
ance of the porcelain without firing the restoration. When
combined with the Fluorescent Spray Glaze, the system becomes
a very cost-effective and efficient way to glaze ceramic, lithium
disilicate and zirconia restorations. By using the Spray Glaze,
a very thin and consistent layer of surface glaze can be applied
to single and multiple restorations in mere seconds without filling
in the surface anatomy. This preserves the desired texture. By
sealing the surface with the Spray Glaze, not only is light trans-
mitted differently, but the restoration becomes stronger and
impenetrable to oral fluids. The inherent fluorescence in the
spray glaze will also improve continuity of shade matching of a
restoration to natural teeth — both under natural and artificial
light sources that contain ultraviolet light wavelengths. The glaze
can be fired at the same time as the stains, thus saving unneces-
sary firing steps, and will help improve esthetics by providing an
improved depth to the shades.
Of course no discussion on color and shading would be
complete without a review of the three dimensions of color:
hue, value and chroma. Hue is of course the dimension of color
that enables us to distinguish one color from another. Value is
the dimension of color that allows us to describe the relative
differences in whiteness or blackness. A restoration with a low
value would be very dark, whereas a crown with a high value
would appear bright by comparison. Value can therefore be used
to describe a restoration in terms of its brightness, lightness or
brilliance. Value can probably be argued in terms of dental resto-
rations as the most important of the three color dimensions.
Interestingly, the human eye cannot detect subtle differences in
hue or chroma, and variations in value are more easily detected.
Finally, chroma refers to the relative concentration or strength,
saturation or intensity of a hue. The more intense a color is, the
higher its chroma value.
It is this author’s preference to use LT (low translucency)
blocks as often as possible. In order for us as clinicians to prepare
a tooth enough to allow for the block manufacturer’s recom-
mended reduction thicknesses for strength and fracture resis-
tance, we will in effect prepare more of the tooth than the normal
enamel layer present in situ. Clinical preparations often entail
complete enamel removal to at least the cervical margin and into
the dentin apparatus of the tooth. Therefore, in my opinion, this
may allow for too much translucency in a given high-tranlucency
monochromatic block. Thus, the subsequent restoration will be
thicker than the particular tooth’s own enamel and will, in effect,
be too translucent. Excessively translucent components of the
restoration will then potentially provoke undesirable gray effects
in the restoration. This author prefers instead to rely more on
the stain-and-glaze process to develop the restoration’s color
contrast, translucency and fluorescence. Indenco’s Polychro-
matic Frit Shading System provides the ability to do this with
ease and accuracy.
The first example of the use of the Polychromatic Frit System
involved the replacement of two failing posterior porcelain fused
to metal crowns (Fig. 3) with Ivoclar’s eMax LT A2 block on
tooth #15 and a CeltraDuo LT A2 block on #14. The two existing
crown restorations were removed, and the teeth re-prepared
to remove recurrent caries. The final tooth preperations were
then imaged with CEREC Omnicam and designed concurrently
in 4.3 software.
After successful try-in of both milled restorations, staining and
glazing was performed with the Indenco System. Vita A shade
Fig. 3: Failing crowns
Fig. 4: Crowns cemented
