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VOLUME 39 • NUMBER 5•MAY2008 391
QUINTESSENCE INTERNATIONAL
The nature of fluorosis, its genesis and path-
ology, as well as the histologic properties of
fluorosed dental enamel, has been the focus
of many studies.1–4 Depending on the fluoride
levels of drinking water, a prevalence of up to
54% of dental fluorosis seems to be evident.5
However, mild to moderate fluorotic mottling
in contemporary literature is considered a pri-
marily esthetic problem.6–8 McKnight et al7
provided evidence that dental fluorosis is per-
ceived more as an esthetic concern than
other enamel opacities. Also, literature on oral
health–related quality of life9and psychoso-
cial aspects of fluorotic stains6points out that
there is an esthetic treatment need in cases of
dental fluorosis. Thus, many publications
have been dedicated to the esthetic correc-
tion of fluorotic stains. Besides veneering and
crowning to correct incisor esthetics as a field-
A randomized CIE L*a*b* evaluation of external
bleaching therapy effects on fluorotic enamel
stains
Michael Knösel, Dr Med Dent1/Rengin Attin, Dr Med Dent2/
Klaus Becker3/Thomas Attin, Dr Med Dent4
Objective: To evaluate the effect of external bleaching on the color and luminosity of fluo-
rotic stains and adjacent, normally mineralized enamel areas by means of CIE L*a*b*
colorimetry.Method and Materials: Eighteen adolescents with mild to moderate fluorotic
stains were randomly assigned to either bleaching group A (n = 9) or control group B.
Eligibility criteria were fluorotic stained maxillary incisors or canines and the informed
consent of the participants and their guardians. Using a colorimeter, CIE L*a*b* values of
maxillary incisors and canines were assessed at baseline (T1) in the center of the fluorotic
stained area (F1) and at adjacent, normally mineralized enamel areas (F2). Then, external
bleaching with Illuminé office (30% hydrogen peroxide, Dentsply DeTrey) was performed
for 60 minutes, followed by color reassessment (T2). After 14 days (T3), a 2-week home
bleaching period with a daily bleaching time of 1 hour with Illuminé home (15% car-
bamide peroxide, Dentsply DeTrey) was conducted with subsequent color determination
(T4). Results: After completion of bleaching therapy, 96.0% of all fluorotic areas (F1) and
100% of normal enamel areas (F2) showed a significant change within group A, com-
pared to 29.4% in control group B. Comparing the collective ⌬E (L*, a*, b*) of F1 and F2,
60.0% of all areas showed significant differences after completion of bleaching therapy,
compared to 88.0% initially. Of group B sites, 82.4% showed color differences in the
beginning (T1) and 88.2% at the end (T4). Conclusion: Whereas a single 1-hour session
of in-office bleaching with 30% hydrogen peroxide does not significantly affect the color
and luminosity of fluorotic teeth, a 14-day period of home bleaching leads to an assimila-
tion of the color of the fluorotic stain with the color of surrounding enamel areas due to dif-
ferent responses of sound and fluorotic enamel to the bleaching regime. (Quintessence Int
2008;39:391–399)
Key words: CIE L*a*b* colorimetry, external bleaching, fluorotic stains
1Assistant Professor, Department of Orthodontics and Dento-
facial Orthopedics, Center of Dentistry, Georg-August-
University,Göttingen, Germany.
2Consultant, Zürich, Switzerland.
3Research Assistant, Clinic for Preventive Dentistry, Perio-
dontology, and Cariology, University of Zürich, Zürich,
Switzerland.
4Professor and Head, Clinic for Preventive Dentistry, Perio-
dontology, and Cariology, University of Zürich, Zürich,
Switzerland.
Correspondence: Dr Michael Knösel, Department of
Orthodontics and Dentofacial Orthopedics, Center of Dentistry,
Georg-August-University, Robert-Koch-Str. 40, Göttingen,
Germany 37099. E-mail:mknoesel@yahoo.de
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392 VOLUME 39 • NUMBER 5•MAY2008
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Knösel et al
tested solution for severe fluorotic stains,32
main alternative approaches have been estab-
lished to treat fluorosis-stained teeth; first, the
microabrasive method,10–12 and second,
changing the perception of the stains by
bleaching,13,14 as well as combinations of both
methods.15,16
Welbury and Shaw17 suggest a paste of
hydrochloric acid and pumice as the treat-
ment of choice in cases of fluorotic stained
teeth. Comparing an acid-bleach combina-
tion technique for treating fluorotic incisors to
a singular acid technique, Wong15 reported
no clinical differences in either treatment
time or esthetic results. Later, Train et al10 rec-
ommended the abrasive technique as defini-
tive treatment only for teeth with mild fluoro-
sis, because of enamel-surface alteration
mostly in severe and moderate cases.
Similarly, Akpata3suggested that the choice
among bleaching, abrasive, or restorative
correction be based on the severity of fluoro-
sis. Using a 35% hydrogen peroxide bleach-
ing, Bussadori et al14 succeeded in providing
a more uniform appearance to incisors
affected by fluorosis, since the color of the
fluorotic areas matched better with the
remaining tooth surface after the bleaching
process.
CIE L*a*b* colorimetry has been estab-
lished as a method for assessing color
changes and efficacy of color-changing
agents.18–23
Whereas Chen et al24 showed in a scan-
ning electron microscopic study the effect of
bleaching solutions on fluorotic stained
enamel, Giambro et al25 were the first to eval-
uate the character of mottled human enamel
by means of CIE L*a*b* colorimetry.
These days, the esthetic treatment of
bleaching fluorotic stains is common prac-
tice. Given the vast assortment of different
bleaching agents currently available, CIE
L*a*b* evaluation seems instrumental in
making the effects of different bleaching
agents or microabrasive methods on fluorot-
ic stains comparable.
However, there is a lack of information
about how much the objective color parame-
ters of the CIE L*a*b* system might be
altered in fluorotic and adjacent nonfluorotic
enamel by bleaching. Since no CIE L*a*b*
evaluation of color changes in bleaching den-
tal fluorosis has been conducted yet, this
study aims at providing a basis for comparing
the efficiency of different bleaching agents or
methods in the treatment of fluorotic stains.
The objective of the present study was to
evaluate the change in fluorotic stains and
surrounding, nonfluorotic enamel areas
under the effect of external bleaching by
means of CIE L*a*b* colorimetry and, fur-
thermore, to appraise patient perception of
the esthetic appearance of stains after a sin-
gle bleaching therapy. The null hypothesis
was that the percentage of collective ⌬E
(L*a*b*) of fluorotic stains and surrounding
enamel surfaces does not decrease after
completion of the presented bleaching
regime compared to baseline.
METHOD AND MATERIALS
During a period of 6 months, every patient in
the Department of Orthodontics, Göttingen
University, who met the eligibility criteria was
informed about the present study design; of
the 584 patients, 20 Caucasian subjects met
the criteria, 2 of whom refused to participate.
The remaining 18 subjects (7 males, 11
females; mean age 18.4 years, SD 4.3 years)
were randomly assigned by lot to either bleach-
ing group A (n = 9) or control group B (n = 9).
This study was approved by the ethics
committee of Göttingen University. Eligibility
criteria were mild to moderate fluorotic
stained maxillary incisors or canines and the
informed consent of the subjects and their
guardians for participating in the study.
Exclusion criteria were hypersensitivities,
proximal caries, insufficient restorations,
younger than 14 years, and gingival dis-
eases. The total enamel surfaces eligible for
assessment were 25 in group A and 17 in
group B.
The setup of the study is presented in Fig
1. All measurements were performed in the
Department of Orthodontics at the Göttingen
University Hospital. For baseline examination
(T1) of both groups, color determination of
carefully wetted maxillary incisors and
canines was performed chairside in well-lit,
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VOLUME 39 • NUMBER 5•MAY2008 393
QUINTESSENCE INTERNATIONAL
Knösel et al
standardized, ambient conditions (ie, the
same chair position and assessment field illu-
mination were maintained throughout all
assessments) using a colorimeter (ShadeEye,
Shofu) recording CIE L*a*b* values.
The CIE L*a*b* system includes 3 chan-
nels. The first of these channels describes the
object’s luminance (parameter L*), while the
2 other channels mark the chrominance (axis
of value a* reaching from green to red; axis of
b* from blue to yellow) (Fig 2). Th same oper-
ator performed all CIE L*a*b* determina-
tions. The colorimeter was used according to
the manufacturer’s instructions. In pre-series
assessments of maxillary enamel surfaces of
3 subjects performed at a 3-day interval, no
relevant differences were detected among the
respective measurements.
With group A, baseline color determina-
tions (T1) were performed immediately
before initiation of the in-office bleaching ses-
sion in the area of the initial lesions (F1) and
at adjacent, normally developed enamel
areas (F2) by placing the nozzle of the col-
orimeter on these areas. The localization of
F2 for every site was noted so that it could be
retrieved in the subsequent color determina-
tions (Fig 3).
Then, Illuminé office bleaching gel (30%
hydrogen peroxide, Dentsply DeTrey) was
applied using a tray 1 time for 60 minutes
onto the anterior maxillary teeth. Per the
manufacturer’s instructions, neither heat nor
light activation of the bleaching gel was per-
formed. After the 60-minute treatment, the
color determination was repeated (T2). After
an interval of 2 weeks and reassessment (T3),
a 14-day home-bleaching regimen for group
A was begun for 1 hour per day with Illuminé
home (15% carbamide peroxide, Dentsply
DeTrey). After 14 days, color determinations
were repeated (T4).
Fig 1 Setup of the study. Color assessments were con-
ducted at T1 to T4.
Fig 2 The CIE L*a*b* coordinate system for chrominance and lumi-
nance. Parameter L* corresponds to the degree of lightness in the
Munsell system, while the a* and the b* values give the position on the
red or green axis (+a* = red, –a* = green) and yellow or blue axis (+b* =
yellow,–b* = blue), respectively.
Bleaching group (A)
T1
Office bleaching
60 min T2 14-day interval T3
Home bleaching
1h/d for 14 d T4
Control group (B)
T1 28-day interval T4
L = 100
White
Black
L = 0
–a
Green
+b
Yellow
Blue
–b
Red
+a
Fig 3 Color determinations were performed at the center of the fluo-
rotic stained areas (F1) and at adjacent, normally mineralized enamel
areas (F2).
F2
F1
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QUINTESSENCE INTERNATIONAL
Knösel et al
In group B, color was assessed at base-
line (T1) and then repeated after a 4-week
interval (T4) (see Fig 1).
Evaluation of patient satisfaction
With the help of a questionnaire, patients’
subjective satisfaction concerning the out-
come of the bleaching therapy was evaluated
(scale 1 to 10), as was the occurrence of
adverse effects during bleaching (Fig 4).
Statistical analysis of color change
Color determinations at F1 and F2 were per-
formed 4 times (T1 to T4) in both groups.
Statistical analysis was performed using the
Statistica program (StatSoft). Mann-Whitney
Utest and Fisher exact test (P= .05) were
applied for calculating the significance of the
differences in groups A and B at any time
point (T1 to T4). Paired ttests (P= .05) were
used to compare the changes between F1
and F2 at time points T1 to T4.
394 VOLUME 39 • NUMBER 5•MAY2008
Questionnaire: Expectation, Outcome, and Side Effects of Bleaching Therapy
To what extent is fluorotic mottling bothering you?
12345678910
1 = not at all 10 = strongly
Satisfaction with outcome after office bleach session
12345678910
1 = discontented, expectations not fulfilled 10 = complete satisfaction
Satisfaction with outcome after home bleaching
12345678910
1 = discontented, expectations not fulfilled 10 = complete satisfaction
Side effects: Hypersensitive teeth during or after bleaching
12345678910
1 = not acceptable 10 = no side effects
Side effects: Rough enamel surface after bleaching
12345678910
1 = not acceptable 10 = no side effects
Side effects: Gingival (gums) problems during or after bleaching
12345678910
1 = not acceptable 10 = no side effects
Expenditure of time
12345678910
1 = not appropriate 10 = appropriate
Would you recommend this kind of bleaching therapy to your best friend?
YES NO
Thank you for your cooperation!
Fig 4 The questionnaire used for evaluation of adverse effects and patient satisfaction.
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VOLUME 39 • NUMBER 5•MAY2008 395
QUINTESSENCE INTERNATIONAL
Knösel et al
Determination of clinical visibility:
Analysis of CIE (L*a*b*) values
Although a ⌬E difference of 3 units is some-
times regarded as an indicator for mismatching
colors, according to most studies concern-
ing color stability, a color change is said to be
clinically visible in any site with ⌬E data high-
er than 3.7 units.19 Therefore, thresholds of
3.0 and 3.7 units were established for CIE
L*a*b* ⌬E.
The collective ⌬E data of areas F1 and F2
before bleaching (T1), after completion of the
office session (T2), after the rest interval (T3),
and after completion of home bleaching ther-
apy (T4), were evaluated on the basis of the
following equation18:
⌬E(Fx, Tx–Fy,Ty) = [(LFx, Tx – LFy, Ty)2+ (aFx, Tx – aFy,
Ty)2+ (bFx, Tx – bFy, Ty)2]1/2
F1 and F2 data were then individually
examined at T2, T3, and T4.
RESULTS
Collective ⌬E (L*a*b*)
According to trial power analysis, at least 15
sites were needed to reveal relevant ⌬E
(L*a*b*) differences of at least 3.0 units in
our trial; 25 sites in group A and 17 in group
B were assessed. Comparing the collective
⌬E (L*a*b*) of F1 and F2, 52.0% of all areas
showed significant differences after comple-
tion of bleaching therapy, compared to
88.0% initially, indicating a better color
matching of these 2 areas compared to
baseline (Table 1a). Of group B sites, 82.4%
showed color differences in the beginning
(T1) and 88.2% at the end (T4) (Table 1b).
Under the premise of 3.0 units as the thresh-
old for ⌬E (L*a*b*), 96.0% of all fluorotic
areas (F1) and 100% of area F2 showed a
significant change after completion of
bleaching therapy, compared to 29.4% in
control group B (F1 and F2) (Tables 2a, 2b,
3a, and 3b).
T1 T2 T3 T4
F1 – F2 n % n % n % n %
DE > 3.0 units 22 88.0 20 80.0 15 60.0 15 60.0
DE > 3.7 units 22 88.0 20 80.0 12 48.0 13 52.0
DE(F1T1 – F2T1) = [(LF1T1 – LF2T1)2+ (aF1T1 – aF2T1)2+ (bF1T1 – bF2T1)2]1/2 gives the color difference between reference area (F2) and WSL
(white spot lesion) area (F1) at baseline (T1).
DE(F1T2 – F2T1) = [(LF1T2 – LF2T2)2+ (aF1T2 – aF2T2)2+ (bF1T2 – bF2T2)2]1/2 gives the color difference between F2 and F1 after completion of
the office session (T2).
DE(F1T3 – F2T3) = [(LF1T3 – LF2T3)2+ (aF1T3 – aF2T3)2+ (bF1T3 – bF2T3)2]1/2 gives the color difference between F2 and F1 after the 14-day
interval (T3).
DE(F1T4 – F2T4) = [(LF1T4 – LF2T4)2+ (aF1T4 – aF2T4)2+ (bF1T4 – bF2T4)2]1/2 gives the color difference between F2 and F1 after completion of
office and home sessions (T4).
Table 1a No. and percentages of sites with DE > 3.0 or > 3.7 units in the areas
F1 vs F2 in bleaching group A
T1 T4
F1 – F2 n % n %
DE > 3.0 units 14 82.4 15 88.2
DE > 3.7 units 12 70.6 13 76.5
DE(F1T1 – F2T1) = [(LF1T1 – LF2T1)2+ (aF1T1 – aF2T1)2+ (bF1T1 – bF2T1)2]1/2 gives the color difference between reference area (F2) and WSL
area (F1) at baseline (T1).
DE(F1T4 – F2T4) = [(LF1T4 – LF2T4)2+ (aF1T4 – aF2T4)2+ (bF1T4 – bF2T4)2]1/2 gives the color difference between F2 and F1 after the 28-day
control interval (T4).
Tab l e 1b No. and percentages of sites with DE > 3.0 or > 3.7 units in the areas
F1 vs F2 in control group B
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Color development during therapy:
Segregated ⌬E data of (L*), (a*), (b*)
Beyond analysis of collective CIE (L*a*b*)
⌬E data, the segregated (L*a*b*) values
were regarded at each time point T1 to T4 to
judge the color development during bleach-
ing therapy.
CIE L* data. In group A, there was no sig-
nificant change after office bleaching (T2), in
either F1 or in F2, and no significant change
after the 14-day inactive interval (T3). At T4,
there was a significant increase of L* value in
F1 (␣= .005) and in F2 (␣= .002), indicating
that lightness of both areas increased signifi-
cantly compared to baseline (T1).
In control group B, there were no significant
changes either in F1 or in F2 at any time point.
CIE a* data. In group A, as well as in con-
trol group B, there were no significant
changes at the time points T2 and T3 com-
pared to baseline, at either F1 or F2 sites. At
T4, there was a significant decrease of a*
value in the fluorotic areas F1, but not in F2
or the control group.
CIE b* data. In group A, there was no sig-
nificant change after office bleaching in
either F1 or F2. After the 14-day interval (T3),
a significant decrease (␣= .0003) compared
to baseline was noted at T3, as well as at T4
(␣= .000001), indicating a change of color
coordinates from yellow to blue domain. In
control group B, no significant changes (F1,
F2) were noted (T1, T2, T3, T4).
The mean CIE (L*a*b*) data for all meas-
urements are presented in Table 4.
Analysis of questionnaire
All patients of group A were satisfied with the
outcome of the bleaching therapy and would
recommend this kind of bleaching therapy to
a friend. After finishing the home bleaching
period, they subjectively felt the fluorotic
stains were less visible than before bleach-
ing. In control group B, patients did not judge
fluorotic stains as less visible after the 4-week
period than at baseline. With the exception of
slight hypersensitivities (minor grade 8 on
our adverse effect scale from 1 to 10 (where
T2 T3 T4
F1 n % n % n %
DE > 3.0 units 16 64.0 15 60.0 24 96.0
DE > 3.7 units 14 56.0 12 48.0 20 80.0
DE(F1T1 – F1T2) = [(LF1T1 – LF1T2)2+ (aF1T1 – aF1T2)2+ (bF1T1 – bF1T2)2]1/2 gives the color
changes of F1 after completion of the office session (T2).
DE(F1T1 – F1T3) = [(LF1T1 – LF1T3)2+ (aF1T1 – aF1T3)2+ (bF1T1 – bF1T3)2]1/2 gives the color
changes of F1 after the 14-day interval (T3).
DE(F1T1 – F1T4) = [(LF1T1 – LF1T4)2+ (aF1T1 – aF1T4)2+ (bF1T1 – bF1T4)2]1/2 gives the color
changes of F1 after completion of the office and home sessions (T4).
Table 2a No. and percentages of sites with DE > 3.0 or
> 3.7 units in area F1 in bleaching group A
T4
F1 n %
DE > 3.0 units 5 29.4
DE > 3.7 units 5 29.4
DE(F1T1 – F1T4) = [(LF1T1 – LF1T4)2+ (aF1T1 – aF1T4)2+ (bF1T1 –
bF1T4)2]1/2 gives the color changes of F1 after the 28-day con-
trol interval (T4).
Tab l e 2b No. and percentages of
sites with DE > 3.0 or > 3.7
units in area F1 in control
group B
T2 T3 T4
F2 n % n % n %
DE > 3.0 units 12 48.0 17 68.0 25 100.0
DE > 3.7 units 10 40.0 17 68.0 24 96.0
DE(F2T1 – F2T2) = [(LF2T1 – LF2T2)2+ (aF2T1 – aF2T2)2+ (bF2T1 – bF2T2)2]1/2 gives the color
changes of F2 after completion of the office session (T2).
DE(F2T1 – F2T3) = [(LF2T1 – LF2T3)2+ (aF2T1 – aF2T3)2+ (bF2T1 – bF2T3)2]1/2 gives the color
changes of F2 after the 14-day interval (T3).
DE(F2T1–F2T4) = [(LF2T1 – LF2T4)2+ (aF2T1 – aF2T4)2+ (bF2T1 – bF2T4)2]1/2 gives the color changes
of F2 after completion of the office and home sessions (T4).
Table 3a No. and percentages of sites with DE > 3.0
or > 3.7 units in area F2 in bleaching group A
T4
F2 n %
DE > 3.0 units 5 29.4
DE > 3.7 units 4 23.5
DE(F2T1 – F2T4) = [(LF2T1 – LF2T4)2+ (aF2T1 – aF2T4)2+ (bF2T1 –
bF2T4)2]1/2 gives the color changes of reference area (F2) after
the 28-day control interval (T4).
Tab l e 3b No. and percentages of
sites with DE > 3.0 or > 3.7
units in area F2 in control
group B
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Knösel et al
grade 10 indicated no hypersensitivities at
all; see Fig 4), patients did not report any
adverse effects or discomfort.
DISCUSSION
According to Johnston and Kao,19 color dif-
ferences are clinically visible to the naked eye
in cases with ⌬E (L*a*b*) exceeding 3.7
units.Of the bleached sites (F1, F2), 88%
exceeded the 3.7-unit threshold before
bleaching (T1), as did 52% in the end (T4).
The respective ⌬E (L*a*b*) values were sig-
nificant according to Fisher exact test (P=
.01). Thus, the null hypothesis was rejected.
In control group B, no significant changes
were noted, which leads to the assumption
that single bleaching therapy provides a
more uniform, esthetic appearance to enam-
el surfaces of fluorotic stained teeth.
On closer look at segregated ⌬E (L*),
(a*), (b*) values at the distinct time points T1
to T4, no significant changes in F1 or in F2
after the initial hour of in-office bleaching (T2)
with 30% hydrogen peroxide were notice-
able, and the color differences between the 2
sites (F1, F2) were not significantly reduced,
which was in accordance with the patients’
recorded self-perception.
Collective ⌬E data of area F1 (bleaching
group A) was not significantly increased
between T2 and T3 (see Table 2a), but did
increase in area F2 from 48% at T2 to 68% at
T3 (⌬E T2 to T3; see Table 3a). On closer
look, it is most likely due to the significant
decrease of b* value in F2 (␣= .0003) com-
pared to baseline, which seems to be respon-
sible for significantly reduced collective ⌬E
between F1 and F2 at T3 (see Table 1a):
There were no significant changes regarding
L* or a* data at T3. A decrease of b* value is
equivalent to a color change from yellow
to blue direction (see Fig 2). According to
the colorimeter manufacturer’s description,
the measuring unit digitally analyzes the
shades along with hue, value, and chroma
without being affected by lighting conditions.
Although we attempted with extraordinary dili-
gence to provide identical ambient illumina-
tion, completely reproducible conditions on
convex enamel surfaces can hardly be
achieved in vivo. For example, a slightly differ-
ent head position may alter the refraction of
the ambient light within the enamel surface.
The manual positioning of the colorimeter’s
nozzle on the teeth may also mark a source of
potential imprecision, as its incline is likely to
affect the shades recorded by the sensor.
Therefore, we cannot exclude the possibility
T1 T2 T3 T4
Area Mean SD Mean SD Mean SD Mean SD
Group A (n = 25)
L F1 75.39 5.19 76.77 4.99 77.01 4.09 79.77 4.44
a F1 –0.29 1.07 –0.6 0.74 –0.85 1.25 –1.04 0.89
b F1 10.59 6.33 8.27 3.97 7.65 2.98 4.62 3.43
L F2 75.18 5.48 77.33 5.28 78.12 4.70 80.32 4.61
a F2 –0.22 0.97 –0.32 0.90 0.31 1.57 –0.42 1.30
b F2 15.42 4.07 13.4 4.52 10.56 3.60 8.6 3.10
Group B (n = 17)
L F1 78.46 4.30 — — — — 78.6 4.21
a F1 –0.82 0.98 — — — — –0.58 1.00
b F1 11.56 4.49 — — — — 10.79 4.92
L F2 79.25 5.21 — — — — 79.29 5.22
a F2 –0.67 1.12 — — — — –0.61 1.25
b F2 14.21 4.86 — — — — 13.49 5.86
Tab l e 4 Mean values (SD) of L*, a*, b* in groups A and B
at the respective time points
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Knösel et al
that value b* with in vivo assessments is more
affected by lighting conditions and adjust-
ment of the colorimeter’s nozzle on the con-
vex enamel surfaces than is warranted by the
manufacturer.
After bleaching, collective ⌬E (F1 versus
F2) was reduced significantly, which is due to
a significant change of all segregated ⌬E
(L*a*b*) data (group A), except from a* value
in area F2. Since a lower value a* means a
color change on the axis from red/brownish to
green, it might be assumed that small stains of
a more brownish color within the fluorotic area
F1 (and lacking in F2) were removed.
According to power analysis, at least 15
sites were needed to reveal relevant ⌬E
(L*a*b*) differences of at least 3.0 units in our
trial. Since 25 sites in group A and 17 in group
B were assessed, it is assumed that the trial
findings can be generalized. However, all par-
ticipants were Caucasian and from a single
geographic location (Göttingen, Germany).
Presuming there are no differences in the reac-
tion of fluorotic teeth in different populations, it
is likely that the results obtained would also
apply to cases with mild to moderate fluorosis
in other geographic locations. Considering the
number of assessed sites, it is hypothesized
that overall evidence is provided. However,
because the results in this study were obtained
from a sample of 18 subjects, further research
concerning routine CIE (L*a*b*) evaluation on
new samples would be useful to corroborate
the results in this study.
A pronounced increase of patient con-
tentment was registered at the end of the
home bleaching session (T4). Perceived
adverse effects remained in the area of the
expectations, which was about 30%.26
CONCLUSIONS
1. A single 1-hour session of in-office bleach-
ing with 30% hydrogen peroxide does not
significantly affect the color and luminosi-
ty of fluorotic teeth.
2. After 14 days of home bleaching with 15%
carbamide peroxide, the color of moder-
ate fluorotic stains assimilates with sur-
rounding, normally developed enamel
areas due to different responses of sound
and fluorotic enamel to the bleaching
regime.
3. According to patient statements, the sin-
gle bleaching therapy seems to be a sat-
isfying nonabrasive approach in cases of
mild or moderate fluorosis.
4. Further research concerning routine CIE
L*a*b* evaluation on new samples
would be useful to corroborate the results
in this study.
REFERENCES
1. Fejerskov O, Manji F, Baelum V. The nature and
mechanisms of dental fluorosis in man. J Dent Res
1990;69(spec no):692–700.
2. Sapov K, Gedalia I, Grobler S, et al. A laboratory
assessment of enamel hypoplasia of teeth with
varying severities of dental fluorosis. J Oral Rehabil
1999;26:672–677.
3. Ak pata ES. Occurrence and management of dental
fluorosis. Int Dent J 2001;51:325–333.
4. Levy SM. An update on fluorides and fluorosis. J Can
Dent Assoc 2003;69:286–291.
5. Tabari ED, Ellwood R, Rugg-Gunn AJ, Evans DJ,
Davies RM. Dental fluorosis in permanent incisor
teeth in relation to water fluoridation, social depri-
vation and toothpaste use in infancy. Br Dent J
2000;189:216–220.
6. Sujak SL, Abdul Kadir R, Dom TN. Esthetic percep-
tion and psychosocial impact of developmental
enamel defects among Malaysian adolescents. J
Oral Sci 2004;46:221–226.
7. McKnight CB, Levy SM, Cooper SE, Jakobsen JR. A
pilot study of esthetic perceptions of dental fluoro-
sis vs.selected other dental conditions. ASDC J Dent
Child 1998;65:233–238.
8. Chikte UM, Louw AJ, Stander I.Perceptions of fluoro-
sis in northern Cape communities. SADJ 2001;56:
528–532.
9. Robinson PG, Nalweyiso N, Busingye J,Whitworth J.
Subjective impacts of dental caries and fluorosis in
rural Ugandan children. Community Dent Health
2005;22:231–236.
10. Train TE, McWhorter AG,Seale NS, Wilson CF,Guo IY.
Examination of esthetic improvement and surface
alteration following microabrasion in fluorotic
human incisors in vivo. Pediatr Dent 1996;18:
353–362.
11. Price RB, Loney RW, Doyle MG, Moulding MB. An
evaluation of a technique to remove stains from
teeth using microabrasion. J Am Dent Assoc
2003;134:1066–1071.
Knosel111.qxd 3/14/08 4:03 PM Page 398
COPYRIGHT © 2008 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO
PART OF THIS ARTICLE MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER
VOLUME 39 • NUMBER 5•MAY2008 399
QUINTESSENCE INTERNATIONAL
Knösel et al
12. Limeback H, Vieira AP, Lawrence H. Improving
esthetically objectionable human enamel fluorosis
with a simple microabrasion technique. Eur J Oral
Sci 2006;114(suppl 1):123–126.
13. Glock ner K, Ebeleseder K, Stadtler P.The bleaching
of stained anterior teeth. Schweiz Monatsschr
Zahnmed 1997;107:413–425.
14. Bussadori SK, do Rego MA, da Silva PE, Pinto MM,
Pinto AC.Esthetic alternative for fluorosis blemishes
with the usage of a dual bleaching system based on
hydrogen peroxide at 35%. J Clin Pediatr Dent
2004;28:143–146.
15. Wong M. A clinical comparison of treatments for
endemic dental fluorosis.J Endod 1991;17:343–345.
16. Scherer W, Quattrone J, Chang J, David S,
Vijayaraghavan T.Removal of intrinsic enamel stains
with vital bleaching and modified microabrasion.
Am J Dent 1991;4:99–102.
17. Welbury RR, Shaw L. A simple technique for removal
of mottling, opacities and pigmentation from
enamel. Dent Update 1990;17:161–163.
18. CIE-Colorimetry. Official recommendations of the
International Commission on Illumination.
Publication CIE [supplement No. 21]. Paris: Bureau
Central de la CIE, 1978:15–30.
19. Johnston WM, Kao EC. Assessments of appearance
match by visual observation and clinical colorime-
try. J Dent Res 1989;68:819–822.
20. de Carvalho EM, Robazza CR, Lage-Marques JL.
Spectrophotometric and visual analysis of internal
dental bleaching utilizing laser and heat as catalyz-
ing sources [in Portuguese]. Pesqui Odontol Bras
2002;16:337–342.
21. Wiegand A, Vollmer D, Foitzik M, Attin R, Attin T.
Efficacy of different whitening modalities on
bovine enamel and dentin. Clin Oral Investig
2005;9:91–97.
22. Yalcin F, Gurgan S. Bleaching-induced colour
change in plastic filling materials. J Biomater Appl
2005;19:187–195.
23. Ley M, Wagner T, Bizhang M.The effect of different
fluoridation methods on the red wine staining
potential on intensively bleached enamel in vitro.
Am J Dent 2006;19:80–84.
24. Chen JH, Wu XJ, Xi SC, You GF. Scanning electron
micrographic analysis of the effect of bleaching
solutions on fluorosed enamel. Quintessence Int
1989;20:825–829.
25. Giambro NJ, Prostak K, Den Besten PK.
Characterization of fluorosed human enamel by
color reflectance, ultrastructure, and elemental
composition. Caries Res 1995;29:251–257.
26. Haywood VB, Leonard RH, Nelson CF, Brunson WD.
Effectiveness, side effects and long-term status of
nightguard vital bleaching. J Am Dent Assoc
1994;125:1219–1226.
Knosel111.qxd 3/14/08 4:03 PM Page 399
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