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Spectrophotometric Evaluation of the Influence of Different Backgrounds on the Color of Glass-Infiltrated Ceramic Veneers Dimitrios Charisis, CDT, DDS, MS Clinical Associate, Department of Prosthodontics, School of Dentistry National and Kapodistrian University of Athens, Greece
Spiridon-Oumvertos Koutayas, CDT, DDS, Dr Med Dent Assistant Professor, Department of Prosthodontics, School of Dentistry Albert-Ludwig University, Freiburg, Germany
Photini Kamposiora, DDS, MS, Dr Dent Lecturer, Department of Prosthodontics, School of Dentistry National and Kapodistrian University of Athens, Greece
Asterios Doukoudakis, DDS, MS, Dr Dent FICD Professor and Chairman, Department of Prosthodontics, School of Dentistry National and Kapodistrian University of Athens, Greece
Correspondence to: Dr Dimitrios Charisis 44 Eftihidou Str, Athens 116 34, Greece; fax: 30 210 7567117; e-mail:
[email protected].
142 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY VOLUME 1 • NUMBER 2 • AUGUST 2006
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Abstract The purpose of this spectrophotometric
trophotometer. Mean color differences (ΔE)
study was to evaluate the influence of dif-
between each study group and the control
ferent color backgrounds on Vita In-Ceram
group were: 3.79 for S2M2; 7.24 for S5M1;
(Vident) glass-infiltrated ceramic veneers.
5.86 for A2M2, and 7.32 for A5M1. Two-way
A total of 50 color background disks were
ANOVA showed statistically significant dif-
fabricated from Vitadur Alpha 2M2 (n = 30)
ferences in ΔE between all groups. Howev-
and 5M1 (n = 20) dentin porcelain (Vi-
er, a t test revealed that the statistically sig-
dent). Ceramic veneer disks were fabricat-
nificant differences only existed between
ed from In-Ceram Spinell (n = 20) or In-
groups S2M2/S5M1, A2M2/A5M1, and
Ceram Alumina (n = 20) glass-infiltrated
S2M2/A2M2. The results suggest that vac-
core veneered using Vitadur Alpha 2M2
uum infiltration with a translucent glass pro-
dentin porcelain. In addition, 10 ceramic
vides the Spinell and Alumina ceramic ve-
veneer disks were fabricated from felds-
neers with increased semi-translucency,
pathic dentin porcelain Vitadur Alpha 2M2.
which makes them highly influenced by
The
were
discolored backgrounds. In-Ceram Spinell
bonded onto the color background speci-
ceramic
veneer
specimens
glass-infiltrated ceramic veneers could be
mens using dual-curing luting composite
considered as an alternative to conven-
cement, creating the following groups
tional feldspathic veneers for the restora-
(each n = 10): S2M2 (Spinell/2M2), S5M1
tion
(Spinell/5M1), A2M2 (Alumina/2M2), A5M1
Spinell and Alumina ceramic veneers
(Alumina/5M1), and control (Vitadur Al-
could enhance the final color establish-
pha/2M2). L*a*b* color coordinates were
ment of discolored teeth, the results would
measured five times for each specimen
not be clinically acceptable.
using a Vita Easyshade (Vident) spec-
(Eur J Esthet Dent 2006;1:142–156.)
of
nondiscolored
teeth.
Although
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Esthetic treatment planning for discolored
fabricating ceramic veneers using these
anterior teeth using ceramic veneers has
materials in a 0.2- to 0.4-mm modified ce-
presented a significant restorative chal-
ramic core (instead of the 0.5 mm suggest-
1–4
Appropriate
ed for all-ceramic crowns) veneered with
bleaching usually offers good short-term
feldspathic porcelain (0.3 to 0.9 mm in
esthetic results for intact natural teeth with
width).24–26 It is assumed that these bilayer
slight or moderate discoloration; however,
veneers will provide adequate masking of
bleaching procedures are not always pre-
discoloration because of the controlled
dictable for severe discolorations.5–7 Ce-
opacity of the core and approximate natural-
ramic veneers are widely used in contem-
looking teeth with an essential depth
porary esthetic dentistry because they are
of translucency resulting from the semi-
lenge for several decades.
3,4,8
have good long-term
transparent behavior of the veneering
prognosis,9–11 and ultimately lead to an im-
material. Nevertheless, little scientific data is
minimally invasive,
12,13
proved esthetic outcome.
available concerning the ability of conven-
The clinical application of ceramic veneers is a very promising approach for the
tional feldspathic or bilayer veneers to successfully restore discolored teeth.
restoration of nondiscolored anterior teeth;
Zhang et al27 illustrated that a 0.2-mm
however, the viability of color matching ve-
densely sintered aluminium oxide core
neers in the discolored dentition mainly
(Procera, Nobel Biocare) has in itself a de-
depends on the severity of the discol-
gree of masking capability, while veneering
oration and the remaining tooth sub-
with feldspathic porcelain (Procera AllCer-
14,15
In these cases, the problem lies
am) in a total thickness of 0.6 mm can neu-
in achieving natural tooth shades using ce-
tralize the color of dark substrates and suc-
ramic veneers. Enamel preservation for
cessfully modify the final shade. In a
successful bonding leaves only 0.5 to 1.0
subsequent study of identical bilayer ve-
mm available (cervical to incisal third) for
neers, Zhang et al28 demonstrated that the
ceramic
the
increase of porcelain chroma produces a
stance.
layering,
thereby
16
limiting
Efforts to achieve pre-
yellow shade and decreases the value of
dictable color management have included
the final color of the restoration. Moreover,
methods such as adding opaque porce-
Okamura et al29 examined feldspathic ve-
lain masses to feldspathic ceramic ve-
neers (Procera AllCeram) with a total thick-
shade possiblities.
17–19
neers,
using porcelain veneering tech-
niques,20,21
or
selecting 22,23
opaque
ness of 0.7 mm and bilayer veneers with
luting
0.25- or 0.4-mm thick densely sintered alu-
However, it has re-
minium oxide core (Procera) and pro-
mained very difficult to fabricate a felds-
posed that the bilayer veneers with the
pathic ceramic veneer that can offer both
0.25-mm core could offer sufficient mask-
optimal masking and a natural appear-
ing for discolored teeth.
composite cements.
ance in the restoration of moderate or
Accurate and reliable color assessment
severe discolorations. Current technology
of both teeth and restorations is crucial for
in dental ceramics includes new high-
effective communication of instructions
toughness ceramics such as glass-infiltrated
to a dental laboratory and ultimately a
aluminium oxide and yttrium-stabilized zirco-
successful
nium dioxide. Many clinicians have begun
measurements performed using visual
144 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY VOLUME 1 • NUMBER 2 • AUGUST 2006
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outcome.
However,
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Method and materials
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niques are highly subjective. Recently, electronic intraoral devices such as col-
A total of 50 disk-shaped color specimens
orimeters
and
10.0 mm in diameter and 2.0 mm in thick-
ShadeVision, X-Rite) and spectrophotome-
ness were made out of Vitadur Alpha felds-
ters (eg, Color-Eye 7000A, GretagMacbeth
pathic dentin porcelain. For the fabrication,
and Vita Easy-Shade, Vident) were intro-
two different color shades, 2M2 (n = 30)
duced to eliminate the subjectivity of the
and 5M1 (n = 20) were selected in order
human eye. These devices are easy-to-
to imitate the shade of a natural and a dis-
use, high-precision measurement tools
colored tooth, respectively (Fig 1).
(eg,
ShadeEye,
Shofu
that can objectively detect color differences
In addition, 50 disk-shaped ceramic ve-
and metrically deliver consistent results us-
neer specimens with a 10.0-mm diameter
ing the CIE (Commission International de
and a total thickness of 0.7 mm were fab-
l’Eclairage [illumination]) L*a*b* system in
ricated as follows: (1) 10 specimens of
order to improve the communication be-
Vitadur
Alpha
2M2
feldspathic
dentin
tween the dentist and the laboratory re-
porcelain, (2) 20 specimens of a 0.4-mm-
garding color determination.30,31
thick In-Ceram Spinell glass-infiltrated core
Vita Easyshade, the newly developed
veneered using the Vitadur Alpha 2M2
visible-range spectrophotometer used in
dentin porcelain, and (3) 20 specimens of
the present study, captures the full visible
a 0.4-mm-thick In-Ceram Alumina glass-
light spectrum of 400 to 700 nm. Using the
infiltrated core veneered using the Vitadur
color-matching functions of the standard
Alpha 2M2 dentin porcelain.
observer
and
the
spectrum
of
the
For the fabrication of the Spinell and Alu-
illuminant, it converts the measurement of
mina cores, a disk-shaped wax pattern 10.0
the spectral reflectance of the color into a
mm in diameter and 0.5 mm in thickness
tri-stimulus value (XYZ) or an international-
was initially carved with the use of a mod-
ly accepted numerical form (ie, L*a*b*),
eling wax (Bellewax, Belle de St. Claire),
which provides a highly detailed definition
and a silicone (Zetalabor, Zhermack) im-
of the color measured.32
pression was taken. The silicone index was
The purpose of this spectrophotometric
cut to the level of the wax disk, then fixed
study was to determine whether Vita
onto a plate made from class IV dental
In-Ceram (Vident) glass-infiltrated ceram-
stone (Velmix Stone, Kerr). This resulted in
ic veneers could mask discolorations sat-
a 10.0-mm-diameter, 0.5-mm-thick mold
isfactorily. Specifically, the study evaluated
with silicone walls and dental stone base to
the influence of two different color back-
facilitate duplicating procedures. After the
grounds (Vitadur Alpha 2M2 and 5M1, Vi-
application of an insulated gel (Insulation
dent) on the color of bilayer ceramic ve-
Gel, Vita) to the mold, In-Ceram slicker
neers made from a glass-infiltrated core
(Spinell or Alumina) was mixed according
(In-Ceram Spinell or In-Ceram Alumina)
to the manufacturer’s instructions and
veneered with a feldspathic porcelain (Vi-
placed in the mold using the slip-cast tech-
tadur Alpha).
nique. When the In-Ceram slicker had dried, the silicone material was displaced and the disk-shaped core was sintered on
145 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY VOLUME 1 • NUMBER 2 • AUGUST 2006
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Disk-shaped color background specimens made of feldspathic dentin porcelain. (left) 2M2 represents
normal tooth shade; (right) 5M1 represents discolored tooth shade.
the dental stone plate in a special furnace
held at this temperature for 10 minutes and
(Inceramat 3, Vita) at 1,180°C for Spinell and
under vacuum for 21 minutes. The glass-
1,120°C for Alumina (both for 2 hours at the
layered Alumina cores were initially pre-
final
sintering
dried at 600°C for 6 minutes, heated to
process, the final thickness of the cores was
1,120°C for 12 minutes, then held at this
controlled with 3-point measurements using
temperature for 30 minutes and under
a calliper (SDI original, Upplands Väsby),
vacuum for 41 minutes. After the glass-
and where necessary cores were leveled
infiltration firing, specimens were allowed
down using 400-grit glasspaper in order to
to cool to room temperature in the open
achieve a uniform thickness of 0.4 mm.
furnace.
temperature).
After
the
Excess
remaining
glass
was
lanthanum-glass
removed using a heatless rotating stone
powder Vita S11 (Vident) was mixed with
instrument at 10,000 rpm and afterwards by
distilled water, providing a homogeneous
sandblasting with aluminum oxide (50 μm)
mixture of which a thin layer was applied
at 2.5 bar compressed air. Finally, an addi-
to both sintered cores using a small brush.
tional glass control firing was accomplished
Glass infiltration for Spinell sintered cores
(starting at 600°C without pre-drying, heat-
was performed using a glass fiber pad
ing for 5 minutes, holding at 1,000°C for 5
(Fibrous Pad, Vita) and for Alumina cores
minutes) without vacuum, and excess glass
using a platinum firing foil (Pt/Au 95/5, Her-
again was removed by sandblasting (Fig 2).
A
semi-transparent
aeus) in a special furnace (Vacumat 40, Vi-
Veneering of both Spinell and Alumina
ta). The glass-layered Spinell cores were
cores was performed using the Vitadur Al-
initially pre-dried at 600°C for 6 minutes,
pha 2M2 feldspathic dentin porcelain ac-
heated up to 1,100°C for 12 minutes, then
cording to manufacturer’s instructions and
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Fig 2
In-Ceram Spinell (left) and Alumina (right) cores after glass infiltration with S11 glass (Vita) under vacuum.
Fig 3
In-Ceram Spinell (left) and Alumina (right) ceramic veneer specimens after veneering using the Vitadur
Alpha 2M2 feldspathic dentin porcelain.
fired at 950°C to 960°C. No internal or ex-
rpm and the specimens self-glazed at
ternal staining was used. All specimens
920°C without vacuum (Fig 3).
were polished following the same proce-
After bonding the ceramic veneer speci-
dure—rotating diamond burs of differing
mens onto the color background speci-
grits (654, Brasseler) were used at 15,000
mens, the 50 specimens provided were
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Study specimens from control (far left), S2M2 (top left), S5M1 (top right), A2M2 (bottom left), and A5M1
(bottom right).
divided into five groups of 10 specimens
signed alignment apparatus33 (Fig 5) and
each (Fig 4): S2M2 and S5M1 groups con-
the dual-curing luting composite Panavia F
sisted of In-Ceram Spinell veneer speci-
Light (Kuraray) according to a protocol
mens, bonded onto Vitadur Alpha 2M2 and
published previously,34 resulting in a stan-
5M1 color backgrounds, respectively; A2M2
dardized mean thickness of composite.
and A5M1 groups comprised In-Ceram
The veneered surface of each disk was
Alumina veneer specimens bonded onto
fixed to a plexiglass acrylic tube with the
Vitadur Alpha 2M2 and 5M1 color back-
use of a bonding agent (Optibond, Kerr),
grounds, respectively; and the control group
then attached to the upper part of the
(CG) was Vitadur Alpha 2M2 veneer speci-
bonding apparatus. The dual-curing luting
mens, bonded onto 2M2 color back-
composite was then placed on the nonve-
grounds.
neered surface of each disk-like ceramic
trasonically cleaned in 96% alcohol for 2
veneer specimen and placed under 750g/cm2 pressure onto the appropriate color
minutes, then dried. The bonding proce-
background specimen. Excess composite
dure was performed using a specially de-
cement was removed with sponge pellets,
Prior to bonding, all specimens were ul-
148 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY VOLUME 1 • NUMBER 2 • AUGUST 2006
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The specially designed alignment apparatus used for bonding the ceramic veneer specimens onto the
color background specimens.
and after 20 seconds of light curing an
tion and measurement process, and the
oxygen-blocking gel (Oxyguard II, Kuraray)
other two analyze the light that is internally
was applied for 3 minutes.
scattered by the material. The spectrome-
The spectrophotometric evaluation was
ters
have
separate
receiver
elements
carried out using the Vita Easyshade spec-
spaced at different distances from the light
trophotometer, which uses a continuous
source and effectively measure the color of
light source over the full visible and near in-
a material at different depths.35
frared spectrums and a color temperature
A ceramic block of known color, provid-
of 3,350°K provided by a 20-W halogen
ed by the manufacturer, was used for the
stabilized tungsten lamp. The handpiece of
calibration of the spectrophotometer. When
the spectrophotometer contains an outer
the device was in the calibration mode, the
ring of 19 fiber optics 1 mm in diameter
probe of the device was placed into the cal-
used to illuminate the material (tooth or ce-
ibration holder and then, after a small
ramic) and three separate spectrometers;
amount of pressure was applied to activate
one spectrometer continuously monitors
the calibration switch, a series of spectrom-
the output of the lamp during the calibra-
eter measurements were made with the
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lamp shutter off (“dark” records) or on
found after the spectrophotometric proce-
(“white” records), and all three spectrome-
dure are shown in Fig 6. The evaluation of
ters were normalized. According to the
L* mean values (Table 1) showed that Alu-
manufacturer, the lamp spectrometer is nor-
mina veneers were whiter than convention-
malized to a white (artificial) light standard,
al feldspathic dentin porcelain or Spinell ve-
and the two sample spectrometers are nor-
neers when used in combination with 2M2
malized to the known color of the calibration
backgrounds. Moreover, Spinell veneers
block. This process permits all color vari-
were more grayish than Alumina veneers
ables in the system to be calibrated.35
when used in combination with 5M1 back-
Furthermore, in order to minimize the
grounds. The evaluation of a* mean values
“edge-loss” phenomenon of the diffused
revealed that both Spinell and Alumina ve-
reflectance, every specimen was firmly
neers presented a lack of red in combina-
adapted into a custom-made base, which
tion with 2M2 backgrounds, while they were
was fabricated from a self-curing acrylic
more reddish over 5M1 backgrounds. The
resin (Jet Tooth Shade, Lang Dental). For
evaluation of b* mean values exhibited a
the same reason, according to the manu-
significant lack of yellow in all study groups.
facturer, it is important to have the light re-
All study groups exhibited changes in
ceiver (probe) as close as possible to the
the color relative to the control group. Mean
specimen to collect the maximum amount
color differences were: 3.79 for S2M2; 7.24
of light from the specimen, independent of
for S5M1; 5.86 for A2M2, and 7.32 for A5M1
surface characteristics or angle. Therefore,
(see Table 1). The two-way ANOVA showed
during the spectrophotometric procedure,
statistically significant differences in ΔE val-
the fiber-optic probe of the spectropho-
ues between all groups (P = .011, α = .05)
tometer was tightly placed onto the center
(Table 2). However, the t test for equality of
of the external (polished) surface of each
variances (α = .05) revealed statistically
specimen, and L*a*b* color coordinates
significant differences between the groups
were registered and recorded five times for
S2M2 and S5M1 (P = .000); A2M2 and
36
each specimen.
Mean values of the color differences (ΔE) between the control group and each
A5M1 (P =.034) and S2M2 and A2M2 (P = .005), but not between the groups S5M1 and A5M1 (P = .834).
of the study groups were calculated using the equation ΔE = (ΔL*2 + Δa*2 + Δb*2)1/2 and compared to the reported clinical vis-
Discussion
ible threshold (ΔE ≥ 3.7) found by Johnston and Kao.30 The statistical analysis of the da-
Currently, many patients recognize the val-
ta was carried out by a two-way analysis of
ue of ceramic veneers as a conservative
variance (ANOVA) followed by a t test.
treatment alternative to traditional crowns primarily
because
they
promote
the
preservation of natural tooth structure and
Results
offer a natural-looking appearance.37 The clinical application of ceramic veneers can
Mean values of L*a*b* color coordinates of
embrace an extensive range of esthetic
each study group and the control group
restorative
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however,
most
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100
Mean values
80 60 40 20 0
L*
a*
b*
S2M2
79.57 (± 0.40)
0.85 (± 0.07)
22.88 (± 0.64)
A2M2
79.26 (± 1.52)
0.64 (± 0.08)
20.17 (± 1.07)
CG
76.77 (± 1.06)
1.45 (± 0.23)
25.21 (± 0.59)
A5M1
75.39 (± 1.64)
1.73 (± 0.18)
18.31 (± 1.01)
S5M1
73.49 (± 0.85)
2.30 (± 0.20)
19.00 (± 0.69)
Fig 6
Individual mean L*a*b* values (± SD) registered by the spectrophotometer for control and
study groups.
Table 1 Groups S2M2 S5M1 A2M2 A5M1
Table 2
Color differences between the control group and each study group Mean ⌬L* 2.80 –3.28 2.49 –1.38
Mean ⌬a* –0.60 0.85 –0.81 0.28
Mean ⌬b* –2.33 –6.21 –5.04 –6.90
Minimum ⌬E 1.43 6.40 3.23 5.92
Maximum ⌬E 4.93 8.32 9.40 9.33
Mean ⌬E (± SD) 3.79 (± 1.06) 7.24 (± 0.62) 5.86 (± 1.74) 7.32 (± 0.99)
Two-way ANOVA of color differences
Source Corrected model Intercept Ceramic veneer Color background Ceramic veneer/ color background*
Type III sum of squares 81.596 1464.974 11.567 60.099 9.930
Error Total Corrected total
49.875 1596.417 131.470
df 3 1 1 1 1 36 40 39
Mean square 27.199 1464.947 11.567 60.099 9.930
F score 19.632 1057.415 8.349 43.380 7.168
P .000 .000 .006 .000 .011
Partial Eta squared 0.621 0.967 0.188 0.546 0.166
1.385
*R2 = 0.621 (adjusted R2 = 0.589).
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encountered
man teeth and represents an average
problems with shade matching, particular-
shade of discoloration. The 2M2 color
ly when attempting to match natural teeth
background was selected because it exists
to ceramic veneer restorations, especially
in 26% of human teeth and represents a
over discolored teeth.38
desirable color for prostheses.42,43
restorative
dentists
have
Conventional veneers made from felds-
Ceramic veneer specimens were fabri-
pathic porcelain provide an essential depth
cated using standardized methods to con-
of translucency that approximates that of
trol the thickness of both the core and ve-
natural teeth, but the final color of the
neering materials. The total thickness of
restoration is highly influenced by the color
each specimen corresponded to that of a
of the underlying prepared tooth.14,15,17 Con-
middle third of an all-ceramic veneer
24–26
and in vitro stud-
restoration. For the glass infiltration of both
ies27,28 have considered the use of bilayer
Alumina and Spinell cores, the study de-
veneer restorations, whose optical proper-
sign included as a standardized parame-
ties are mostly dependent on the thickness
ter the use of a clear glass (S11) under vac-
and consistency of the selected ceramic
uum procedure, which provides a more
core material to mask discolored teeth.39,40
translucent core.21 This particular core does
temporary clinical trials
The fabrication of glass-infiltrated ce-
not affect the color performance of the ve-
ramic veneers was not included in the ap-
neering material (Vitadur Alpha 2M2) and
plications for the In-Ceram system stated
therefore contributes to the masking abili-
by Claus in 1990.41 However, the fabrication
ty of the selected core materials in relation
of an In-Ceram ceramic veneer is viable
to their refraction index. In addition, no in-
with the slight modification of the ceramic
ternal or external staining was used, since
core from the proposed 0.6 to 0.4 mm. The
this procedure alters the color parame-
core potentially could offer enhanced op-
ters.44 Finally, all specimens were subject-
tical properties to a veneer restoration
ed to an identical polishing and glazing
based on the opacity of the material used
procedure to create a microstructure that
(Alumina or Spinell). The optical behavior
contributed to a uniform diffused re-
of such restorations could be further con-
flectance of incident light during the spec-
trolled during glass infiltration (with or with-
trophotometric evaluation.45,46
out vacuum), veneering, and cementation
A semi-translucent light-colored dual-
procedures. The present study examined
curing luting composite (Panavia F Light)
the feasibility of In-Ceram Alumina and
was selected for all study groups in order
Spinell glass-infiltrated ceramic veneers to
to minimize the influence of the color of the
provide an esthetic outcome and clinically
cementation mean and to allow a better
acceptable masking when combined with
evaluation of the optical properties of the
discolored teeth.
ceramic veneer specimens. In addition, it
To simulate teeth with and without
has been demonstrated that the bonding
discoloration, color backgrounds were fab-
procedure followed in this study provides
ricated from two different color shades—
a mean composite cement thickness of 80
feldspathic dentin porcelain 5M1 and 2M2,
μm,34 which is considered to be clinically
respectively. The 5M1 color background
acceptable for the middle third of a fixed
was selected because it exists in 2% of hu-
all-ceramic restoration.47 Therefore, the ce-
152 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY VOLUME 1 • NUMBER 2 • AUGUST 2006
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ment thickness did not negatively impact
ferent backgrounds (2M2 or 5M1) signifi-
the standardization of the study.
cantly altered the final color shade of both
Current digital shade-scanning technol-
Spinell and Alumina veneer specimens.
ogy establishes a new standard for quality
The above conclusion was particularly re-
control, enhancing the communication be-
vealed by the t test, which showed statisti-
tween the restorative dentist, the laborato-
cally significant differences between the
ry, and the patient and offers a precise col-
groups S2M2 and S5M1 (P = .000) and
or
research
A2M2 and A5M1 (P = .034). In addition, the
purposes. The spectrophotometer used in
t test showed statistically significant differ-
the current study fulfills these expectations,
ences between the groups S2M2 and
providing a measurement accuracy of
A2M2 (P = .005), which suggests that the
measurement
32
device
for
and color reproduction that is more
use of In-Ceram ceramic veneers with a
reliable than human perception and hence
different glass-infiltrated core (Spinell or
more accurate than visual shade assess-
Alumina) can statistically influence the final
ment.48 When the fiber-optic probe of the
esthetic outcome for nondiscolored teeth.
spectrophotometer is placed on the exter-
The failure of the Alumina veneer speci-
nal surface of the specimen, the main
mens (group A2M2) to reproduce a clini-
problem encountered is a partial loss of
cally acceptable color when bonded over
the reflected light.43 As previously de-
2M2 backgrounds could be a result of the
scribed, the “edge-loss” effect of the dif-
increased opacity of the Alumina core rel-
fused reflectance was reduced by the use
ative to the Spinell core. On the other hand,
of a custom-made acrylic base and the
Spinell veneer specimens in combination
firm adaptation of the fiber-optic probe on
with the color background 2M2 (group
the surface of every specimen.
S2M2) showed a ΔE mean value of 3.79,
92%
The quantitative assessments of color
which is only marginally higher than the
differences (⌬E values) found between the
clinically visible threshold of 3.7; thus the
study groups and the control group can
color performance of these veneers could
only be compared to clinically visible
be considered reasonably accurate. For
thresholds reported by other research-
that reason, Spinell veneers could be con-
30,49–52
ers.
Because of a lack of clear param-
sidered an alternative to the conventional
eters (thresholds) for judging color differ-
feldspathic veneers for the restoration of
ences of materials as clinically acceptable
nondiscolored teeth.
or unacceptable, the ΔE value of 3.7 stat30
The color differences found between the
was adopted to
groups S5M1 and A5M1 were not statisti-
rate the color of the ceramic veneers ex-
cally significant (P = .834), indicating that
amined in the present study as a match in
the clinical application of In-Ceram ve-
the oral environment. All mean ΔE values
neers with a Spinell versus an Alumina
between the groups and the control group
core would not significantly affect the final
were greater than 3.7 units and therefore
shade of discolored teeth. Although the fi-
visually perceivable according the criteria
nal tooth shade was enhanced by both
of the study.
restorations, the esthetic outcome was not
ed by Johnston and Kao
This is of high clinical relevance be-
by ht
opyrig
C All eR CHARISIS ET eAL cht e
clinically acceptable.
cause it indicates that the presence of dif-
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According to the results, both color
porcelain that presents increased chroma
backgrounds induced changes to the col-
(eg, 2M3) in combination with external
or of the glass-infiltrated ceramic veneers
staining and/or internal staining and/or dif-
relative to the control group. The Alumina
ferent color modifiers. Finally, the lack of
and Spinell veneers inherently exhibit a
yellow exhibited in both Spinell and Alumi-
dissimilar semi-translucency due to their
na veneer specimens potentially could be
ceramic cores; however, because of the
managed with the use of a yellowish glass
under-vacuum infiltration procedure, both
(eg, Vita Al1, Vident) instead of the semi-
glass-infiltrated veneers generally present-
transparent glass (Vita S11) used in the
ed an increased semi-translucency. In ad-
current study.
dition, the evaluation of the individual a*b*
In addition, the study revealed that when
and Δa*Δb* mean values (see Fig 6 and
restoring discolored teeth, Alumina ve-
Table 1) clearly indicated that chroma den-
neers might provide a whiter shade than
sity played an equally important role in the
Spinell veneers because of differences in
achievement of sufficient masking.
the opacity of the core materials. In regard
Since semi-translucency and chroma
to the control of the semi-translucency, it
density are the foremost decisive factors in
has been demonstrated that the perform-
the final tooth shade, it is important to re-
ance of the glass infiltration under vacuum
member that the present study examined
leads to the fabrication of ceramic cores
only the influence of the background color
with higher opacity because of a significant
on the shade of In-Ceram Alumina and
increase in density.21Moreover, it has been
Spinell ceramic veneers. Influencing factors
shown that the glass infiltration of In-Ceram
such as the layering technique and the use
Alumina under vacuum using a glass
of stains or color modifiers, a different glass,
originally
glass infiltration without vacuum, and a dif-
Spinell led to a 9.1% decrease in strength
ferent shade of luting resin cement were
of the Alumina ceramic material21; however,
beyond the purposes of the study.
this reduction in strength could be consid-
marketed
for
the
In-Ceram
According to the theory of complemen-
ered noncritical because the restoration
tary colors and the navigation of the Vita-
can still withstand the reported maximal
pan 3D-Master color guide (Vident), minor
incisive forces.54
color corrections can be accomplished us-
Finally, minor adjustments concerning the
ing the appropriate porcelain layering
control of the semi-translucency can be
technique.20,53 For example, the increased
made through the clinical application of lut-
value (brightness) (⌬L* = 2.80) because of
ing composite cement of the appropriate
the lack of red (⌬a* = –0.60) and yellow
shade.55 Especially when bonding veneers
(⌬b* = –2.33) found in group S2M2 (see
with increased translucency, the use of the
Table 1) can be altered by adding a
appropriate shade of luting composite
red/yellow modifier at a ratio of 1:4 to
cement can potentially contribute to an
achieve an intermediate shade with in-
enhanced color outcome. However, opaque
creased chroma (saturation). Increased
composite cements could be excessively
chroma also could be achieved when
reflective and lead to an unpredictable depth
needed with the use of a feldspathic dentin
of translucency in a veneer restoration.38
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C All eR CHARISIS ET eAL cht e
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tional feldspathic veneers for the restora-
Within the limits of this in vitro study, the
tion of nondiscolored teeth. Furthermore,
following conclusions can be drawn:
In-Ceram Spinell and Alumina ceramic veneers could enhance the final shade
1. Vacuum infiltration with a translucent
of discolored teeth, although not to the
glass provides In-Ceram Spinell and Alu-
extent that the results would be clinically
mina ceramic veneers with increased
acceptable.
semi-translucency, which makes them highly influenced by discolored backgrounds. 2. Regarding the reported clinical visible thresholds,
In-Ceram
Spinell
glass-
infiltrated ceramic veneers could be considered as an alternative to conven-
Acknowledgments The authors are grateful to Vita Zahnfabrik, Bad Säckingen, Germany, for supplying the study materials. They also appreciate the statistical work performed by Sonia Striggon and the advice provided throughout the study by Prof Dr George Eliades.
References 1. Pincus CR. Building mouth personality. J South Calif Dent Assoc 1938;14:125–129. 2. Garber DA, Adar P. Securing the position of ceramic veneers in dentistry. Signature 1997;4(2):2–4. 3. Gürel G. The Science and Art of Porcelain Laminate Veneers. London: Quintessence, 2003. 4. Gürel G. Predictable, precise, and repeatable tooth preparation for porcelain laminate veneers. Pract Proced Aesthet Dent 2003;15:17–24. 5. Faunce F. Management of discolored teeth. Dent Clin North Am 1983;27:657–670. 6. Hattab FN, Qudeimat MA, alRimawi HS. Dental discoloration: An overview. J Esthet Dent 1999;11:291–310. 7. Bartlett D. Bleaching discolored teeth. Dent Update 2001;28:14–18. 8. Magne P, Belser UC. Novel porcelain laminate preparation approach driven by a diagnostic mock-up. J Esthet Restor Dent 2004;16:7–16. 9. Smales RJ, Etemadi S. Longterm survival of porcelain laminate veneers using two preparation designs: A retrospective study. Int J Prosthodont 2004; 17:323–326.
10. Peumans M, De Munck J, Fieuws S, Lambrechts P, Vanherle G, Van Meerbeek B. A prospective ten-year clinical trial of porcelain veneers. J Adhes Dent 2004;6:65–76. 11. Fradeani M, Redemagni M, Corrado M. Porcelain laminate veneers: 6- to 12-year clinical evaluation—A retrospective study. Int J Periodontics Restorative Dent 2005;25:9–17. 12. Cutbirth ST, Geller W. Restoration of maxillary anterior teeth with porcelain laminate veneers. Pract Proced Aesthet Dent 1999;11:443–445. 13. Lowe RA, Nash RW. Indirect laminate veneers: An excellent option to correct elective aesthetic problems. Dent Today 2000;19:84–88. 14. Bichacho N. Porcelain laminates: Integrated concepts in treating diverse aesthetic defects. Pract Periodontics Aesthet Dent 1995;7:13–23. 15. Belser UC, Magne P, Magne M. Ceramic laminate veneers: Continuous evolution of indications. J Esthet Dent 1997;9:197–207. 16. Ferrari M, Patroni S, Balleri P. Measurement of enamel thickness in relation to reduction for etched laminate veneers. Int J Periodontics Restorative Dent 1992;23:407–413.
17. Davis BK, Aquilino SA, Lund PS, Diaz-Arnold AM, Denehy GE. Subjective evaluation of the effect of porcelain opacity on the resultant color of porcelain veneers. Int J Prosthodont 1990;3:567–572. 18. Davis BK, Aquilino SA, Lund PS, Diaz-Arnold AM, Denehy GE. Colorimetric evaluation of the effect of porcelain opacity on the resultant color of porcelain veneers. Int J Prosthodont 1992;5:130–136. 19. Yaman P, Qazi SR, Dennison JB, Razzoog M. Effect of adding opaque porcelain on the final color of porcelain laminates. J Prosthet Dent 1997;77:136–140. 20. Yamada K. Porcelain laminate veneers for discolored teeth using complementary colors. Int J Prosthodont 1993;6:242–247. 21. Magne P, Belser U. Esthetic improvements and in vitro testing of In-Ceram Alumina and Spinell ceramic. Int J Prosthodont 1997;10:459–466. 22. Davis BK, Papcum LJ, Johnston WM. Effect of cement shade on final shade of porcelain veneers [abstract 250]. J Dent Res 1991;70(special issue):297.
155 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY VOLUME 1 • NUMBER 2 • AUGUST 2006
CLINICAL APPLICATION
Qu
i
nt
23. Mörmann WH, C Link, Lutz F. Color changes in veneer ceramics caused by bonding composite resins. Acta Med Dent Helv 1996;1:97–102. 24. Hager B, Oden A, Andersson B, Andersson L. Procera AllCeram laminates: A clinical report. J Prosthet Dent 2001;85:231–232. 25. Chu FC, Luk HW, Andersson B, Deng FL, Chow TW. Making porcelain veneers with the Procera AllCeram system studies. Dent Update 2003;30: 454–458,460. 26. Miyasaki M. Aesthetic rehabilitation of severely discolored anterior dentition: Restorative considerations using allceramic veneers. Pract Proced Aesthet Dent 2004;16:277–281. 27. Zhang F, Heydecke G, Razzoog M. Double-layer porcelain veneers: Effect of layering on resulting veneer color. J Prosthet Dent 2000;84:425–431. 28. Zhang F, Zhao Y, Razzoog ME. Effect of layering feldspathic porcelain on resulting veneer color with aluminum oxide core. Zhonghua Kou Qiang Yi Xue Za Zhi 2002;37:206–209. 29. Okamura M, Chen KK, Kakigawa H, Kozono Y. Application of alumina coping to porcelain laminate veneered crown: Part 1. Masking ability for discolored teeth. Dent Mater J 2004;23:180–183. 30. Johnston WM, Kao EC. Assessment of appearance match by visual observation and clinical colorimetry. J Dent Res 1989; 68:819–822. 31. Baltzer A, Kaufmann–Jinoian V. Shading of ceramic crowns using digital tooth shade matching devices. Int J Comput Dent 2005;8:129–152. 32. Study on the relevance of electronic color measurement [press release]. Amsterdam: Academic Centre for Dentistry, Free University of Amsterdam, 2004. 33. Kern M, Thompson VP. Bonding to glass infiltrated alumina ceramic: Adhesive methods and their durability. J Prosthet Dent 1995;73:240–249.
34. Koutayas SO, Kakaboura A, Hussein A, Strub JR. Colorimetric evaluation of the influence of five different restorative materials on the color of veneered densely sintered alumina. J Esthet Restor Dent 2003;15:353–360. 35. The principles of use of a spectrophotometer and its application in the measurement of dental shades [press release]. Morton Grove, IL: JJL Technologies, 2003:1–21. 36. C.I.E. Colorimetry: Official Recommendations of the International Commission on Illumination, ed 2. Paris: Bureau Central de la CIE, 1985. 37. Vallitu PK, Vallitu ASJ, Lassila VP. Dental aesthetics—A survey of attitudes in different groups of patients. J Dent 1995;24: 335–338. 38. Friedman M. Porcelain veneer restorations: A clinician’s opinion about a disturbing trend. J Esthet Restor Dent 2003;13:318–327. 39. Ironside JG. Light transmission of a ceramic core material used in fixed prosthodontics. Quintessence Dent Technol 1993;16:103–106. 40. Paul SJ, Pietrobon N, Schärer P. The new In-Ceram Spinell system—A case report. Int J Periodontics Restorative Dent 1995;15:520–527. 41. Claus H. Vita In-Ceram, a new procedure for preparation of oxide-ceramic crown and bridge framework [in German]. Quintessenz Zahntech 1990;16:35–46. 42. Culpepper W. A comparative study of shade matching procedures. J Prosthet Dent 1970; 24:166–173. 43. Van der Burgt TP, Ten Bosch JJ, Borsboom PCF, Kortsmit WJ. A comparison of new and conventional methods for quantification of tooth color. J Prosthet Dent 1990;63:155–162. 44. Southan D. Factors affecting the translucency of dental porcelain. Quintessence Int 1987;18:197–202.
156 THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY VOLUME 1 • NUMBER 2 • AUGUST 2006
by ht
opyrig
C All eR ech te
vo rbe ha lte n
e ss e n z
45. Obregon A, Goodkind RJ, Schwabacher WB. Effects of opaque and porcelain surface texture on the color of ceramometal restorations. J Prosthet Dent 1981;46:330–340. 46. Kim IJ, Lee YK, Lim BS, Kim CW. Effect of surface topography on the color of dental porcelain. J Mater Sci Mater Med 2003;14:405–409. 47. May KB, Russell MM, Razzoog ME, Lang BR. Precision of fit: The Procera AllCeram crown. J Prosthet Dent 1998;80: 394–404. 48. Paul SJ, Peter A, Rodoni L, Pietrobon N. Conventional visual vs spectrophotometric shade taking for porcelainfused-to-metal crowns: A clinical comparison. Int J Periodontics Restorative Dent 2004;24:222–231. 49. Keuhni G, Marcus RJ. An experiment in visual scaling of small color differences. Color Res 1979;4:83–91. 50. Ruyter IE, Nilner K, Moller B. Color stability of new composite restorative material under accelerated aging. J Dent Res 1987;59:2071–2074. 51. Seghi RR, Hewlett ER, Kim J. Visual and instrumental colorimetric assessment of small color differences on translucent dental porcelain. J Dent Res 1989;68:1760–1764. 52. O’Brien WJ. Color and appearance. In: Dental Materials and Their Selection, ed 3. Chicago: Quintessence, 2002:24–30. 53. Charisis D. Vollkeramische Versorgung [in German]. Quintessenz Zahntech 2005;31: 942–952. 54. Kiliaridis S, Kjellberg H, Wenneberg B, Engstrom C. The relationship between maximal force, bite force endurance, and facial morphology during growth. A cross-sectional study. Acta Odontol Scand 1993;51: 323–331. 55. Touati B, Miara P. Light transmission in bonded ceramic restorations. J Esthet Dent 1993;5:11–18.