Cas clinique Naoto Yuasa

Naoto Yuasa
Introduction
It is an essential requirement for single crowns
surrounded by healthy natural teeth to be in harmony
with the surrounding natural teeth. They have to
harmonize with the teeth on the opposite side in the
same position and their adjacent teeth. Although many
patients have a wide range of requests in different
cases, harmony is the major target.
As far as the requirements are concerned, it is of the
utmost importance that the prostheses should match
the natural teeth. The dental technician is expected
to produce prostheses which are as individualized as
possible and which harmonize with both the color and
the shape of the natural teeth.
Color reproduction is a long-standing problem. A wide
variety of materials have been produced, and a broad
range of theories have been developed and published
connected to this issue. Compared with the generation of
metal-ceramic crowns, an optically more advantageous
solution, zirconium, has recently been found, and it is
becoming more and more widespread nowadays.
However, even now that materials have developed
a lot, true harmony cannot be achieved unless the
prostheses are anatomically individualized, natural
looking and lifelike.
The following article focuses on a few single crown
cases aiming for harmony with the teeth on the
opposite side and the adjacent teeth and would like to
illustrate the important points of harmonization where
it is the most difficult to reproduce color.
AUTUMN 2018
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Materials
In-Ceram Spinell (VITA) +
Cerabien (Noritake)
Description: Internal staining with Noritake Internal
Stain Bright and White to control contrasting density. In
order to create natural look, internal staining on dentin
and enamel structure is applied separately.
Materials
KATANA Zirconia (Noritake) +
Cerabien ZR (Noritake)
Description: There is semi-dry condition in the incisal edge
area due to slightly open lips in daily life. Characterization is
done to match with the semi-dry condition.
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Materials
Metal + Noritake Super
Porcelain EX-3 (Noritake)
Materials
KATANA Zirconia (Noritake) +
Cerabien ZR (Noritake)
Description: Margin porcelain was used in order to
achieve the suitable sub-gingival condition of the
marginal line. It is important to select a base color to
match with the higher value in dentin structure and to
pay attention to balancing the translucency between
the central and lateral teeth since the lateral incisal has
higher translucency on the incisal edge than the centrals.
Staining on the cervical area should be avoided.
Description: It is essential to pay attention to the contrast
of the white band and the layer of the characterization
because the target tooth has a lower contrast on white
band area. In addition, there was a lower value on the
incisal edge due to the enamel loss created by the facet
angle. Special care was taken of creating a balance
between translucency and low-value color.
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Materials
KATANA Zirconia (Noritake) +
Cerabien ZR (Noritake)
Description: In order to show clear mamelon structure
with Internal Stain technique on the upper central,
higher translucency on the incisal area was created with
the help of base color construction. In case of the lower
incisal and lateral teeth, their opacity was adjusted
repeatedly on a quasi-abutment on the model, because
the opacity, the translucency, the target shades and
the layering techniques of porcelains were significantly
affected by the color of the abutment.
Materials
KATANA Zirconia (Noritake) +
Cerabien ZR (Noritake)
Description: The situation is the same as in the
previous case; there is only a thin layering space in the
lower lateral. Therefore, layering is carefully done with
serious consideration of the balance between the value
of dentin structure and translucency.
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Materials
Materials
KATANA Zirconia (Noritake) +
Cerabien ZR (Noritake)
Description: The target tooth has a flat texture on
the facial surface and only orange color on the incisal
area. A precisely simple characterization is necessary,
and the result is immediately seen from the base
color of the dentin structure and the color&thickness
of the enamel structure.
Metal + Noritake Supper
Porcelain EX-3 (Noritake)
Description: There is a quite large white area on the
enamel of right upper central. It is necessary to have
characterization of the dentin structure without
surface characterization. During the internal staining
of the enamel, a white area is made with Internal Stain
White applying Dilution technique in order to create
different varieties of contrast.
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Materials
KATANA Zirconia (Noritake) +
Cerabien ZR (Noritake)
Description: It is widely known that the layering
methods of the anterior and posterior crowns
are different due to the different thickness of
the enamel structure. During posterior layering,
bluish or grayish translucent color and whitish
translucent color are present at the same time, and
opalescence on the surface layer is necessary to
have color designing.
Materials
KATANA Zirconia (Noritake) +
Cerabien ZR (Noritake) on lower
left 1st and 2nd pre-molar, Metal
+ Noritake Supper Porcelain EX-3
(Noritake) on both 1st molars
Description: Description: This is a case of implantsupported
single crowns. Once the articular layering
method of molars is acquired, it is possible to use
the same method for all the molar restorations
with only a small adjustment of the base colors
and balance. The important point of molar color
matching is creating the enamel structure with
translucent porcelain.
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Naoto Yuasa
• 2002 Graduation from Toho Dental College
• 2004 Graduation from Toho Dental College
Advanced Program
• 2004 Working at Kondo Dental Clinic
• 2010 Working AS main ceramist in Otani Dental Clinic,
Kuraray Noritake Dental International Instructor, Chairman
of Yuasa Seminar
Specials thanks to Dr. Ohtani for his
continuous collaboration.
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