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Dental Press J Orthod. 2022;27(5):e2220325
https://doi.org/10.1590/2177-6709.27.5.e2220325.oar
Célia Regina Maio PINZAN-VERCELINO1
https://orcid.org/0000-0002-5419-0079
Suellen Nogueira Linares LIMA2
https://orcid.org/0000-0003-1156-2888
Fernando Félix de Jesus Vieira PEREIRA2
https://orcid.org/0000-0003-4265-9949
Júlio de Araújo GURGEL3
https://orcid.org/0000-0003-4205-0965
Gisele Rodrigues da SILVA4
https://orcid.org/0000-0002-9358-1339
Karina Maria Salvatore de FREITAS5
https://orcid.org/0000-0001-9145-6334
ORIGINAL ARTICLE
Volume 27 - Number 5 - Online
Efficacy of products for bleaching and
whitening under orthodontic brackets
(1) Centro Universitário Uningá, Departamento de Odontologia (Maringá/PR, Brazil). (2) Universidade Ceuma, Departamento
de Odontologia (São Luís/MA, Brazil). (3) Universidade Estadual de São Paulo (UNESP) (Marília/SP, Brazil). (4) Universidade
Federal de Uberlândia, Escola de Odontologia, Departamento de Dentística Operatória e Materiais Odontológicos
(Uberlândia/MG, Brazil). (5) Centro Universitário Uningá, Departamento de Odontologia (Maringá/PR, Brazil).
Submitted: August 05, 2020 • Revised and accepted: November 24, 2021
cepinzan@hotmail.com
How to cite: Pinzan-Vercelino CRM, Lima SNL, Pereira FFJV, Gurgel JA, Silva GR, Freitas KMS. Efficacy of products
for bleaching and whitening under orthodontic brackets. Dental Press J Orthod. 2022;27(5):e2220325.
Dental Press J Orthod. 2022;27(5):e2220325
Pinzan-Vercelino CRM, Lima SNL, Pereira FFJV, Gurgel JA, Silva GR, Freitas KMS —
Efficacy of products for bleaching and whitening under orthodontic brackets
2
ABSTRACT
Introduction: Many patients wearing orthodontic appliances
request alterations in the shade of their teeth during orthodon-
tic treatment. Objective: This study aimed to evaluate the ef-
ficacy of different products for bleaching and whitening under
orthodontic brackets. Methods: Seventy bovine incisors were
randomly divided into five groups (n = 14): C) non-whitening
toothpaste (control); WTsi)hydrated silica whitening tooth-
paste; WThp) 2% hydrogen peroxide whitening toothpaste;
OB)in-office bleaching; and HB)at-home bleaching. Twobuc-
cal surface areas were evaluated using the Easyshade spec-
trophotometer: under the metal bracket (experimental) and
around the bracket (control). The paired t-test, ANOVA, and
Tukey tests were applied for statistical analysis. Results: In-
tragroup comparisons showed that in groups C, WThp and HB,
there were statistically significant differences in the enamel
color changes (ΔEab) between under and around the bracket ar-
eas (C- under bracket = 7.97 ± 2.35, around bracket = 2.86 ± 0.81,
p < 0.01; WThp - under bracket = 4.69 ± 2.98, around brack-
et = 2.05±1.41, p < 0.01; HB- under bracket = 7.41 ± 2.89, around
bracket: 9.86 ±3.32, p = 0.02). Groups WTsi, OB and HB pre-
sented similar perception of tooth whiteness (ΔWID) between
the tested areas. Intergroup comparisons demonstrated that
under the bracket area, the color change (ΔEab) was similar
for all groups, except WThp (C = 7.97 ± 2.35; WTsi = 8.54 ± 3.63;
WThp = 4.69 ± 2.98; OB = 9.31 ± 4.32; HB = 7.41 ± 2.89; p < 0.01).
Conclusions: The dental color changes were effective for the
products tested in groups WTsi, OB and HB in the presence of
metallic orthodontic brackets.
Keywords: Tooth bleaching. Toothpastes. Tooth bleaching
agents. Orthodontic brackets.
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RESUMO
Introdução: Durante o tratamento ortodôntico, muitos pacien-
tes solicitam, também, alteração na cor dos seus dentes. Objetivo:
O presente estudo avaliou diferentes produtos clareadores e
branqueadores, quanto à sua eficácia sob os braquetes ortodôn-
ticos. Métodos: 70 incisivos bovinos foram aleatoriamente divi-
didos em cinco grupos (n = 14): C)dentifrício não branqueador
(controle); WTsi) dentifrício branqueador com sílica hidratada;
WThp)dentifrício branqueador com peróxido de hidrogênio a 2%;
OB)clareamento no consultório e HB)clareamento caseiro. Usan-
do um espectrofotômetro Easyshade, foram avaliadas duas áreas
na superfície vestibular dos dentes: sob o braquete (experimental)
e ao redor do braquete (controle). Para análise estatística, foram
usados ostestest pareado, ANOVA e Tukey. Resultados: As com-
parações intragrupos demonstraram que, nos grupos C, WThp e
HB, ocorreram diferenças estatisticamente significativas nas al-
terações de cor do esmalte(ΔEab) entre as áreas sob o braquete e
ao redor do braquete (C:sob o braquete = 7,97 ± 2,35, ao redor do
braquete = 2,86 ± 0,81, p < 0,01; WThp: sob o braquete = 4,69 ± 2,98,
ao redor do braquete = 2,05 ± 1,41, p < 0,01; HB: sob o braque-
te = 7,41 ± 2,89, ao redor do braquete = 9,86 ± 3,32, p = 0,02). Osgru-
pos WTsi, OB e HB demonstraram semelhanças na percepção do
clareamento(ΔWID) entre as áreas avaliadas. As comparações in-
tergrupos demonstraram que, nas áreas sob os braquetes, as al-
terações de cor (ΔEab) foram semelhantes para os grupos, com exce-
ção do WThp (C = 7,97 ± 2,35; WTsi = 8,54 ± 3,63; WThp = 4,69 ± 2,98;
OB = 9,31 ± 4,32; HB = 7,41 ± 2,89; p < 0,01). Conclusões: As altera-
ções na cor dos dentes foram efetivas para os procedimentos tes-
tados nos grupos WTsi, OB e HB na presença de braquetes metá-
licos ortodônticos.
Palavras-chave: Clareamento dental. Cremes dentais. Agen-
tes clareadores dentais. Braquetes ortodônticos.
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INTRODUCTION
Dental bleaching and alignment are the majority of complaints
from patients who attend dental offices.1-3 Besides the aesthetic
benefits, dental color and position changes have also been
correlated with individuals’ social perception, including more
positive judgments related to social competence and appeal,
intellectual ability, and relationship satisfaction.1,4
Many orthodontic patients request dental bleaching during
orthodontic treatment,5 to simultaneously achieve the desired
dental color and position. Usually, dissatisfaction with the color
of teeth increases when the crowding is solved.2
Dental bleaching and whitening are different processes. Dental
bleaching involves the application of gels containing hydrogen per-
oxide or carbamide peroxide on the tooth surface. Theperoxide
diffuses through the enamel and dentin, producing free radicals
that react with the intrinsic pigments, making the teeth appear
whiter.6,7 A recent study suggested that hydrogen peroxide might
whiten normal dentin by oxidizing the benzene ring of aromatic
amino acids in dentin phosphoprotein, the main noncollagenous
protein located in the organic-inorganic interface, responsible for
the fluorescence and color of normal dentin.8 On the other hand,
dental whitening consists of the removal and control of extrin-
sic tooth stains.7 Currently, many whitening products, with the
promise of rapid and convenient color alteration, are available
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on the market, including whitening toothpastes.7,9,10 Whitening
toothpastes have become popular due to low costs, unrestricted
selling, ease of use, and high availability.7,11
Most whitening products act in one of these mechanisms: chemical
(the use of peroxides for tooth bleaching) or mechanical (removal
of extrinsic stains through abrasive action).7,12 Toothpastes that
act using a mechanical mechanism contain abrasives that only
remove the extrinsic stains, instead of changing the tooth color, as
is observed in a real bleaching action. Some whitening toothpastes
have included peroxide in their formulations; however, the efficacy
of peroxide from toothpaste is questioned regarding the concen-
tration and exposure time during toothbrushing.13
Previous clinical14,15 and laboratory16-19 studies have shown color
alteration under the bracket area using bleaching agents. However,
even with the increasing presence of whitening toothpastes on the
market, the authors are unaware of a study that has been conducted
to test their efficacy on teeth with bonded brackets. Therefore,
the present study aimed to evaluate different products’ efficacy
for bleaching and whitening under orthodontic brackets. The null
hypothesis tested was that there would be no differences in color
change when hydrated silica whitening toothpaste; 2% hydrogen
peroxide whitening toothpaste; in-office dental bleaching using 35%
hydrogen peroxide; and at-home bleaching using 22% carbamide
peroxide procedures are applied on teeth with bonded brackets.
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MATERIAL AND METHODS
The local Animal Ethics Research Committee (CEUA-UNICEUMA,
São Luís/MA, Brazil) approved this in vitro investigation (protocol
0029016). The sample size calculation was based on data previ-
ously described,15,20 using the dental color change (ΔEab) as a refer-
ence variable. The parameters used were: 95% confidence level,
power of 80%, standard deviation of 2.3 ΔEab, and a minimum dif-
ference of 2.7 ΔEab between the means (G*Power software, ver-
sion 3.1.3; Franz Faul, University of Kiel, Kiel, Schleswig-Holstein,
Germany). The minimum number of specimens was determined
to be 12 per group, and 20% was added to this value to increase
the power, thus resulting in 14 teeth per group.
Seventy experimental units were obtained from bovine incisors
aged between 24 and 30 months, and were stored in a refriger-
ated 1% chloramine–T solution, ph7, for 30 days. The following
criteria for tooth selection were used: intact buccal enamel, with
no cracks, no abrasion, or any other crown defect, and similar
size and shade (A3, determined by comparison with a value-ori-
ented shade guide – Vita Toothguide 3D Master; VITA Zahnfabrik,
Bad Säckingen, Bade-Württemberg, Germany). Themorphologi-
cal enamel conditions were evaluated by two researchers, using
a simple magnifying glass. Only in cases of agreement, the teeth
were selected. The researchers inspected 120 teeth and selected
70 from this set. The roots and pulp chamber of the teeth were
removed. The pulp chamber was accessed and extended using a
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conical diamond tip. The dental pulp and debris were removed
using a dental curette and air/water jets. Afterward, the bovine
incisors were stored for 7 days in distilled water.
One matrix was made for each tooth, using high-viscosity sil-
icone, to standardize the color measurement area, and guide
the bracket bonding. In the matrix, two vertically adjacent cir-
cular windows were located close to the center of the crown, on
the buccal surface of the teeth (Fig1): one experimental area
(under the bracket) and one control area (around the bracket).
They were configured using a circular metal-cutting device
measuring 6 mm in diameter (Biopsy Punch, Miltex; York, PA,
USA), corresponding to the diameter of the spectrophotometer
probe (Easyshade Advance 4.0; Vident, Brea, CA, USA).14,15,21,22
A single calibrated operator performed the bonding procedure.
Before brackets bonding, the teeth received dental screening and
dental prophylaxis, using pumice and a rubber cup with a low-speed
handpiece. With the matrix installed on the buccal surface of the
teeth, at the circular opening of the experimental area, 37% phos-
phoric acid gel was applied for 30s, followed by rinsing for 30s, and
drying for 15s. The Transbond XT primer (3M Unitek Orthodontic
Products, Monrovia, CA, USA) was applied, followed by a brief air
spray and light-curing for 20s. Metal brackets (maxillary central
incisor, Standard Edgewise, 0.022 x 0.030-in slot; Morelli, Sorocaba/
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Figure 1: The silicone matrix
made individually for each
tooth, to standardize the col-
or measurement area and
guide the brackets bonding.
SP,Brazil) were bonded on the prepared surface using Transbond
XT light-cure composite resin (3M Unitek Orthodontic Products,
Monrovia, CA, USA). The brackets were positioned at the center of
the experimental area, and held down with 300g force for 10s, using
a tensiometer. Before light-activation, the matrix was removed,
and the excess material was removed using an exploratory probe.
Thecuring process was performed using a LED light-curing unit set
at 1400 mW/cm2 (VALO®, Ultradent, South Jordan, UT, EUA) for 10 s,
5 s on each side (mesial and distal). Thelight intensity was mea-
sured by a radiometer (Demetron LED radiometer, Kerr Sybron
Dental Specialties; Middleton, WI, USA).
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The specimens were numbered and then equally (n=14) and
randomly (Random.org Integer Generator; http://www.ran-
dom.org) divided into five groups (Table 1): C –non-whitening
toothpaste (Colgate Tripla Ação, Colgate-Palmolive, SP, Brazil);
WTsi – hydrated silica whitening toothpaste (Colgate Optic
White, Colgate-Palmolive, NY, USA); WThp –2% hydrogen per-
oxide whitening toothpaste (Colgate Luminous White Advanced
Expert, Colgate-Palmolive, Gua, Guanajuato, Mexico); OB–in-of-
fice bleaching (Whiteness HP 35%, FGM, SC, Brazil); and
HB–at-home bleaching (Whiteness Simple 22% FGM, SC, Brazil).
Toothbrushing simulations were made using a custom-made
automated toothbrushing machine (Biopdi XY, São Carlos/SP,
Brazil) with suspensions prepared with the testing toothpastes
and distilled water, in a 1:2 ratio, in weigh11,12 (course: 3.8 cm;
velocity: 356 rpm). Soft orthodontic toothbrushes were used
(Oral-B Orthodontic Toothbrush 35, P&G, USA). Controlled
time, pressure, and temperature (36 ± 1ºC) were applied.
Table 1: Testing groups: commercial name, relevant ingredients and manufacturer descriptions.
Group Commercial name Relevant ingredients Manufacturer
C Colgate Tripla Ação Sodium monouorophosphate at
0.76% (0.14% w/v uoride ion)
Colgate-Palmolive,
SP, Brazil
WTsi Colgate Optic White Hydrated silica, tetrapotassium pyrophos-
phate, pentasodium triphosphate
Colgate-Palmolive,
NY, USA
WThp Colgate Luminous White
Advanced Expert
Hydrogen peroxide at 2%, sodium monouo-
rophosphate at 0.76%
Colgate-Palmolive,
Gua, Mexico
OB Whiteness HP 35% Hydrogen peroxide at 35% FGM, SC, Brazil
HB Whiteness Simple 22% Carbamide peroxide at 22% FGM, SC, Brazil
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Thespecimens were brushed twice a day for 15 days (500 cycles
in each brushing), totalizing 15,000 cycles of circular mechanical
brushing. After each brushing cycle, specimens were washed
in running water and stored in distilled water at 37ºC.
In group OB, the bleaching agent used was 35% hydrogen
peroxide for the in-office procedure. The gel was applied in
three applications, each one lasting 15 min. Two bleaching ses-
sions were performed, with a 1-week interval between them.
Afterthe bleaching treatment, the teeth surfaces were abun-
dantly washed with water. Between the sessions, the teeth
were stored in distilled water at 37ºC, changed daily.
In group HB, the bleaching agent used was 22% carbamide perox-
ide for at-home bleaching, for 15 consecutive days, being 2 hours
per day. The specimens were stored over cotton gauze soaked
with distilled water throughout the bleaching procedure. After the
bleaching treatment, the teeth surfaces were abundantly washed
with water, and stored in distilled water at 37ºC, changed daily.
Bracket debonding pliers were used to debond the accessories.
Removal of resin remnants was performed using a 12-blade
tungsten carbide bur on low-speed handpiece, at 20,000rpm
without water cooling.
One operator made the color evaluations, using the matrix to
standardize the spectrophotometer probe placement during
consecutive color evaluations.14,15,21,22 The color measurements
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were recorded at baseline and one month after bracket removal,
to give the teeth adequate time to rehydrate.15,23
The color was measured using color coordinates established
by the International Commission on Illumination (CIELab),
using the Easyshade device. The following values were eval-
uated: L*, a*, and b*, in which L* represent the value from
0 (black) to 100 (white), and a* and b* represent the shade,
where a* is the measurement along the red-green axis, and
b* is the measurement along the yellow-blue axis. The color
parameters were measured over a white background. The color
comparison before and after treatment was given by the dif-
ferences between the two shades (ΔEab), which was calculated
using the following formula:ΔEab = [(ΔL*)2 + (Δa*)2+ (Δb*)2]1/2,
where ΔL* = L*(final) - L*(initial); Δa* = a*(final) - a*(initial); and
Δb*= b*(final) - b*(initial). To evaluate the perception of tooth
whiteness, the CIELab-based whiteness index (WID= 0.511L*
−2.324a* −1.100b*) was also calculated. The whiteness index
change (ΔWID) was calculated according to the equation:
ΔWID =WIafter bleaching - WIbaseline.24,25 Three readings were done,
and the values were averaged for statistical purposes. The total
color alteration (ΔEab) was considered the primary outcome.
During the recording of the tooth color and performing the
statistical analyses, the researchers were blinded.
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STATISTICAL ANALYSES
The data were initially submitted to the Shapiro-Wilk test, and
the normality was demonstrated. The compatibility of the base-
line CIELab values between the areas compared (experimen-
tal– under the bracket; and control – around the bracket) was
individually evaluated by paired t-test. The paired t-test was
also applied to the intragroup comparisons between the exper-
imental (under the brackets) and the control (around the brack-
ets) areas, at 1 month after bleaching/whitening procedures.
Theintergroup comparisons were performed using the one-way
ANOVA and Tukey tests. The level of significance adopted was
5%, and statistical analyses were performed using the software
Statistica for Windows version 7.0 (Statsoft, Tulsa, Ok, USA).
RESULTS
The color coordinates evaluated (L*, a*, and b*) were similar
at baseline, for all groups, between under the bracket area
(experimental) and around the bracket area (control), demon-
strating that the areas compared were compatible regarding
color at baseline (Table 2).
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» Intragroup comparisons
Intragroup comparisons showed statistically significant dif-
ferences in color changes (ΔEab) for groups C, WThp and HB,
between under and around the bracket areas after bleaching
and whitening treatments (group C = 7.97 ± 2.35 x 2.86 ± 0.81,
Table 2: Descriptive statistics and intragroup comparisons of CIELab values under the
bracket (experimental) and around the bracket (control) areas at baseline.
SD = standard deviation. Intragroup comparison (paired t-test) (α = 0.05). Groups: C = non-whitening toothpaste;
WTsi = hydrated silica whitening toothpaste; WThp = 2% hydrogen peroxide whitening toothpaste; OB = in-office
bleaching; and HB = at-home bleaching.
Initial
CIELab
UNDER THE BRACKET AREA
(experimental)
Mean ± SD
AROUND THE BRACKET AREA
(control)
Mean ± SD
p
Group C
L89.63 ± 2.04 90.82 ± 1.09 0.07
a1.40 ± 1.19 0.71 ± 0.74 0.09
b25.1 ± 3.65 22.4 ± 3.89 0.07
Group WTsi
L88.8 ± 3.32 90.0 ± 4.41 0.41
a -1.21 ± 2.13 -2.2 ± 1.81 0.19
b26.33 ± 6.02 22.68 ± 5.97 0.11
Group WThp
L90.17 ± 3.35 91.73 ± 1.92 0.14
a -2.61 ± 1.61 -2.24 ± 0.90 0.45
b22.08 ± 3.89 21.68 ± 3.90 0.78
Group OB
L88.25 ± 2.81 89.16 ± 3.36 0.44
a -1.66 ± 0.96 -1.42 ± 1.64 0.64
b 26.27 3.35 25.88 ± 4.53 0.79
Group HB
L89.92 ± 2.85 90.91 ± 2.19 0.31
a1.16 ± 2.00 0.73 ± 1.70 0.55
b26.39 ± 3.39 24.11 ± 3.06 0.07
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p < 0.01; group WThp = 4.69 ± 2.98 x 2.05 ± 1.41, p < 0.01;
groupHB = 7.41 ± 2.89 x 9.86 ± 3.32, p = 0.02). In groups C and
WThp, the under the bracket area demonstrated significantly
greater color change; while in group HB, the around the bracket
area underwent significantly greater color change (Table 3).
Lightness (ΔL*) was statistically greater for groups C and WThp at
under the bracket area (group C = 6.06 ± 2.49x1.08 ± 1.46, p < 0.01;
group WThp = 2.16 ± 3.17x-0.17 ± 1.13, p = 0.02) (Table 3).
Group C had, at under the bracket area, statistically significant
greater reduction in a* (group C = -2.53 ± 1.16 x -1.31 ± 0.72,
p < 0.01) and b* (group C = -3.75 ± 2.26x-0.29 ± 1.92, p < 0.01),
decreasing redness and yellowness, respectively. Group HB
showed a significant reduction in b* (group HB -4.96 ± 2.48 x
-7.78 ± 3.19, p < 0.01) around the bracket area (Table 3).
Tooth whiteness (ΔWID) presented statistically significant dif-
ferences between the areas tested for groups C and WThp
(groupC=9.6 ± 4.3 x 0.2 ± 3.0, p < 0.01; groupWThp=1.8 ± 6.6
x-2.6 ± 3.6, p = 0.03), demonstrating greater alterations for the
under the bracket area (Table 3).
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Table 3: Descriptive statistics, intragroup and intergroup comparisons of CIELab and WID values
under the bracket and around the bracket areas, one month after bleaching.
†Intragroup comparison (paired t-test). Different superscript uppercase letters in columns indicate statistically
significant differences among the groups with ANOVA/Tukey test (α = 0.05). *Statistically significant at p < 0.05.
Groups: C = non-whitening toothpaste; WTsi = hydrated silica whitening toothpaste; WThp = 2% hydrogen
peroxide whitening toothpaste; OB=in-office bleaching; and HB=at-home bleaching.
UNDER THE
BRACKET AREA
(experimental)
Mean ± SD
AROUND THE
BRACKET AREA
(control)
Mean ± SD
p†
ΔEab
C7.97 ± 2.35A2.86 ± 0.81A< 0.01*
WTsi 8.54 ± 3.63A6.17 ± 4.59B0.08
WThp 4.69 ± 2.98B2.05 ± 1.41A< 0.01*
OB 9.31 ± 4.32A10.72 ± 3.23C0.31
HB 7.41 ± 2.89A9.86 ± 3.32C0.02*
p< 0.01* < 0.01*
ΔL*
C6.06 ± 2.49A1.08 ± 1.46AB < 0.01*
WTsi 2.78 ± 4.98B3.32 ± 4.27AC 0.75
WThp 2.16 ± 3.17B-0.17 ± 1.13B0.02*
OB 5.50 ± 3.85A5.99 ± 2.47C0.65
HB 4.57 ± 2.43A5.30 ± 2.13C0.31
p0.01* < 0.01*
Δa*
C-2.53 ± 1.16A-1.31 ± 0.72AB < 0.01*
WTsi -1.65 ± 1.93AB -0.63 ± 1.54A0.12
WThp -0.68 ± 1.31B-0.18 ± 0.60A0.15
OB -2.14 ± 0.98A-2.46 ± 1.70B0.50
HB -2.26 ± 1.08A-1.89 ± 1.34B0.31
p< 0.01* < 0.01*
Δb*
C-3.75 ± 2.26AB -0.29 ± 1.92A< 0.01*
WTsi -5.60 ± 4.28A-3.53 ± 3.97B0.26
WThp -2.43 ± 2.99B-0.74 ± 2.06A0.06
OB -6.69 ± 3.27A-8.22 ± 2.75C0.16
HB -4.96 ± 2.48AB -7.78 ± 3.19C< 0.01*
p< 0.01* < 0.01*
ΔWID
C9.6 ± 4.3A0.2 ± 3.0A< 0.01*
WTsi 7.9 ± 10.9AB 3.5 ± 8.2A0.30
WThp 1.8 ± 6.6B-2.6 ± 3.6A0.03*
OB 11.6 ± 6.5A14.3 ± 6.8B0.33
HB 9.4 ± 5.0A12 ± 6.0B0.17
p< 0.01* < 0.01*
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» Intergroup comparisons
Intergroup comparisons demonstrated that the color change
(ΔEab) was similar for groups C, WTsi, OB, and HB at under the
bracket area (group C = 7.97 ± 2.35; group WTsi = 8.54 ± 3.63;
group OB = 9.31 ± 4.32; group HB = 7.41 ± 2.89) (Table 3).
Onlygroup WThp showed less color variation than the other
groups in this region (group WThp = 4.69 ± 2.98, p< 0.01). In the
around the bracket area, groups C and WThp showed similar
color changes (group C = 2.86 ± 0.81; group WThp = 2.05 ± 1.41),
group WTsi demonstrated different color alteration, in com-
parison with the other groups (group WTsi = 6.17 ± 4.59), and
groups OB and HB showed statistically greater color changes
(group OB = 10.72 ± 3.23; group HB = 9.86 ± 3.32).
At under the bracket area, greater lightness (ΔL*) was observed
for groups C, OB and HB (group C = 6.06 ± 2.49; group OB =
5.50 ± 3.85; group HB = 4.57 ± 2.43; p= 0.01), and at around the
bracket area for OB and HB (group OB = 5.99 ± 2.47; group HB =
5.30 ± 2.13; p< 0.01). The group WThp demonstrated the smallest
lightness change in the control area (group WThp = -0.17 ± 1.13).
The green-red axis (Δa*) showed greater reduction for groups
C, OB and HB at under the bracket area (group C = -2.53 ± 1.16;
group OB = -2.14 ± 0.98; group HB = -2.26 ± 1.08; p< 0.01); and
at around the bracket area for groups OB and HB (group OB =
-2.46 ± 1.70; group HB = -1.89 ± 1.34; p< 0.01).
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At under the bracket area, WTsi and OB demonstrated a sta-
tistically significant greater reduction in Δb* (group WTsi =
-5.60 ± 4.28; group OB = -6.69 ± 3.27; p < 0.01), decreasing
yellowness. At around the bracket area, OB and HB showed
a greater reduction of yellowness (group OB = -8.22 ± 2.75;
groupHB= -7.78 ± 3.19; p < 0.01) (Table 3).
Statistically significant greater tooth whiteness (ΔWID) was
observed for groups C, OB and HB at the under the bracket area
(group C= 9.6 ± 4.3; group OB= 11.6 ± 6.5; group HB=9.4 ± 5.0;
p < 0.01), and for groups OB and HB at the around the bracket
area (group OB= 14.3 ± 6.8; group HB= 12 ± 6.0; p < 0.01).
DISCUSSION
Although previous studies14-19 have evaluated the efficacy of differ-
ent dental bleaching agents under orthodontic brackets, no study
has evaluated the whitening toothpastes. Since many patients
wearing orthodontic appliances perceive changes in the shade of
their teeth, and whitening toothpaste is an easily accessible prod-
uct,12 its efficacy needed to be tested. The null hypothesis was
rejected since, considering the parameters ΔEab and ΔWID, simi-
lar results between under and around the bracket areas were
observed only for groups WTsi, OB, and HB.
The efficacy of whitening and bleaching procedures applied in
the present study was demonstrated, as observed in the results
obtained for the control area (around the bracket). Whiteningor
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bleaching was observed in groups WTsi, OB, and HB by the
evaluation method used, and color changes of approximately
6 to 10 ΔEab were detected.
Previous studies26,27 observed that hydrated silica whitening
toothpaste showed greater color changes than 2% hydrogen
peroxide whitening toothpaste, corroborating with the present
results. This finding suggested that the toothbrushing abra-
sion action was mainly responsible for the color changes.26 The
authors speculate that the low peroxide hydrogen concentra-
tion did not produce enough free radicals to oxidize dentin’s
organic component in the WThp group.28,29 The in-office and
at-home bleaching procedures showed statistically greater
color changes and similarity around the bracket area, corrobo-
rating with previous studies.18,19,21,22,25,30
The area under the bracket showed greater color alteration
and tooth whiteness, when compared with the area around the
bracket, for the non-whitening toothpaste, 2% hydrogen perox-
ide whitening toothpaste, and at-home bleaching procedure.
Previous studies31-34 also observed enamel color changes after
treatment with fixed orthodontic appliances, demonstrating an
increase in the tooth color’s lightness after bracket debonding.
The color change under the brackets is variable. Eliades et al.32
observed that tooth-color differences after debonding and clean-
ing procedures ranged from 5.27 ± 2.21 to 13.7 ± 4.7 ΔEab units.
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Factors such as acid etching, increased roughness, removal of
resin remnants and penetration of resin tags into the enamel
surface may have affected the light scattering of the under
the bracket area.32,34-37 Sardarian et al16 and Lunardi et al17 also
demonstrated statistically significant lower color change under
the bracket than around the bracket, after at-home bleaching
procedure. The peroxide concentration (22%) may also have
influenced this result.22,28,29
The differences in color change between the areas under and
around the brackets were 5.11 units for the non-whitening tooth-
paste group, 2.37 units for hydrated silica whitening toothpaste
group, 2.64 units for 2% hydrogen peroxide whitening toothpaste
group, 1.41 units for the in-office bleaching group, and 2.45 units
for at-home bleaching group. These results demonstrated that
the color change between the areas evaluated was clinically
significant only for the non-whitening toothpaste group, since,
for the other groups, the ΔEab values were below the standard
value for visual perceptibility and clinical detection of color
change (ΔEab 3.7 units).38 Therefore, the color variations proba-
bly would not be perceived by the human eye when hydrated
silica whitening toothpaste, in-office and at-home bleaching
are used in teeth with brackets.
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An average variation of 9.31 and 7.41 of color change (ΔEab) in
the area under the bracket for groups OB and HB was observed,
which agrees with previous studies:Montenegro-Arana etal15
showed a mean variation of 5 to 9 ΔEab; Jadad etal14 demon-
strated a mean variation of 8.5 ΔEab after bleaching treatment in
teeth with orthodontic brackets; and Sardarian et al16 showed
a mean variation of 8.51 to 10.84 ΔEab. The absence of previous
studies evaluating the effect of whitening toothpaste under
orthodontic brackets limits comparisons.
Despite the limitations of in vitro studies, recent studies11,12
have shown similar results after testing the color variation of
whitening toothpastes in vitro and in vivo. Tao et al12 highlighted
that the evaluation of tooth whitening products using in vitro
methods is important for the testing hypotheses and identify-
ing efficacious formulations. Moreover, since this study tested
toothpastes, the standardization of toothbrushing procedure
was important to eliminate bias.
Even though the color change was similar under and around the
bracket for the bleaching and whitening procedures in groups WTsi
and OB, and demonstrated clinical acceptability for HB, it is import-
ant to highlight that the use of these products in an abusive man-
ner may result in enamel alterations and tooth sensitivity.4,15,22,39
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Bleaching is contraindicated in clinical conditions in which the
tooth presents exposed dentin or other enamel tissue changes
that presumably increase its permeability.14
According to the results obtained in the present study, the
in-office dental bleaching using 35% hydrogen peroxide,
at-home bleaching using 22% carbamide peroxide, and the
use of whitening toothpaste containing hydrated silica showed
effectiveness in the presence of metallic orthodontic brackets.
Therefore, in cases where orthodontic patients request dental
bleaching or whitening during orthodontic treatment, these
products may be indicated.
Further studies comparing enamel roughness and possible
physical and/or mechanical alterations in the orthodontic appli-
ances (e.g. wires, brackets and ligatures) must be encouraged.
CONCLUSIONS
Considering the results obtained for the color changes (ΔEab)
and the perception of tooth whiteness (WID), the dental color
changes were effective, in the presence of metallic orthodon-
tic brackets, for the use of whitening toothpaste containing
hydrated silica and in-office dental bleaching with 35% hydrogen
peroxide and at-home bleaching with 22% carbamide peroxide.
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AUTHORS’ CONTRIBUTIONS
Célia R. M. Pinzan-Vercelino (CRMPV)
Suellen N. Linares Lima (SNLL)
Fernando F. de J. V. Pereira (FFJVP)
Júlio de Araújo Gurgel (JAG)
Gisele Rodrigues da Silva (GRS)
Karina M. S. de Freitas (KMSF)
Conception or design of the study:
CRMPV, SNLL
Data acquisition, analysis or
interpretation:
CRMPV, SNLL, FFJVP, JAG, GRS, KMSF
Writing the article:
CRMPV, SNLL, FFJVP, JAG, GRS, KMSF
Critical revision of the article:
CRMPV, SNLL, FFJVP, JAG, GRS, KMSF
Final approval of the article:
CRMPV, SNLL, FFJVP, JAG, GRS, KMSF
Fundraising:
FFJVP
Overall responsibility:
CRMPV
The authors report no commercial, proprietary or financial interest in the products or
companies described in this article.
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