UNIVERSIDADE ESTADUAL PAULISTA
“JÚLIO DE MESQUITA FILHO”
Instituto de Ciência e Tecnologia
Campus de São José dos Campos
ORIGINAL ARTICLE DOI: https://doi.org/10.4322/bds.2024.e4414
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Braz Dent Sci 2024 July/Sept;27 (3): e4414
This is an Open Access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in
any medium, provided the original work is properly cited.
Effect of charcoal-containing toothpastes on roughness and color
stability of bulk-fill resin composites
Efeito de dentifrícios contendo carvão na cor e rugosidade de resinas compostas bulk-fill
Waldemir Francisco VIEIRA-JUNIOR1 , Rafaella Queiróz COSTA2 , Leonardo Santos BARROS2 , Mariana Mayume MORI3 ,
Cecilia Pedroso TURSSI2 , Fabiana Mantovani Gomes FRANÇA2 , Núbia Inocencya Pavesi PINI3,4 , Roberta Tarkany BASTING2
1 - Universidade Estadual de Campinas - UNICAMP, Faculdade de Odontologia de Piracicaba, Departamento de Odontologia Restauradora.
Piracicaba, SP, Brazil.
2 - Faculdade São Leopoldo Mandic, Departamento de Odontologia Restauradora. Campinas, SP, Brazil.
3 - Centro Universitário Ingá - UNINGÁ, Departamento de Odontologia Restauradora. Maringá, PR, Brazil.
4 - Universidade Estadual de Maringá, Departamento de Odontologia Restauradora. Maringá, PR, Brazil.
How to cite: Vieira-Junior WF, Costa RQ, Barros LS, Mori MM, Turssi CP, França FMG, et al. Effect of charcoal-containing toothpastes on
roughness and color stability of bulk-ll resin composites. Braz Dent Sci. 2024;27(3):e4414. https://doi.org/10.4322/bds.2024.e4414
ABSTRACT
Objective: To evaluate the effects of different commercially available charcoal-based toothpastes (CBTs) on
the roughness and color of bulk-ll resin composites (RCs). Materials and Methods: Disc-shaped samples
(6 × 2 mm) were made with nanolled (NF) bulk-ll (Filtek One, 3M Oral Care) or nanohybrid (NH) bulk-ll
(Aura, SDI) RCs. The analyses were performed initially (baseline) and after 10,000 brushing cycles in a tooth-
brushing machine using (n=10): regular toothpaste (Colgate Total 12, Colgate-Palmolive) or three types of
CBTs (Colgate Luminous White Activated Charcoal - Colgate-Palmolive; Black is White - Curaprox; 3D White
Mineral Clean - Oral-B). The specimens were analyzed for roughness (Ra, µm) and quantied by coordinates of
the CIEL*a*b* color space, Vita Classical scale (shade guide unit, SGU), and general color alteration (ΔE
ab
; ΔE
00
).
The data were evaluated using generalized linear models (Ra, L*, b*, ΔE
ab
; ΔE
00
), Mann-Whitney, Kruskal-Wallis,
and Dunn tests (a*; ΔSGU), with α=0.05. Results: Regardless of the toothpaste, Ra increased after brushing,
but was signicantly higher in NH than NF (p=0.0001). L* signicantly decreased after brushing with Black
is White toothpaste (p=0.0027). NF showed higher ΔE00 values after brushing with the CBTs, compared with
regular toothpaste. Moreover, NH exposed to Black is White exhibited higher ΔEab and ΔE00 values than the other
toothpastes (p<0.0001). Conclusion: The roughness alteration was not mediated by the type of toothpaste.
However, the CBTs were able to change the optical properties of bulk-ll RCs, with more pronounced effects,
as observed with Black is White.
KEYWORDS
Activated charcoal; Color; Composite resins; Toothbrushing; Toothpastes.
RESUMO
Objetivo: Avaliar os efeitos de diferentes dentifrícios contendo carvão (DCCs) na rugosidade e cor de resinas
compostas (RCs) bulk-ll. Material e Métodos: Amostras cilíndricas (6 × 2 mm) foram confeccionadas com
as RCs nanoparticulada (NP) bulk-ll (Filtek One, 3M Oral Care) e nano-híbrida (NH) bulk-ll (Aura, SDI). As
análises foram realizadas nos tempos: inicial (baseline) e após 10000 ciclos de escovação em máquina simuladora
utilizando (n = 10): dentifrício regular (Colgate total 12, Colgate-Palmolive) e DCCs (Colgate Luminous White
Carvão Ativado - Colgate-Palmolive; Black is White - Curaprox; 3D White Mineral Clean - Oral-B). As amostras
foram analisadas quanto à rugosidade (Ra, µm) e quanticadas nas coordenadas do sistema CIEL*a*b*, na
escala Vita Classical (SGU), e em valores de alteração geral da cor (ΔEab; ΔE00). Os dados foram avaliados por
modelos lineares generalizados (Ra, L*, b*, ΔEab; ΔE00), testes de Mann Whitney, Kruskal-Wallis e Dunn (a*;
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Braz Dent Sci 2024 July/Sept;27 (3): e4414
Vieira-Junior WF et al.
Effect of charcoal-containing toothpastes on roughness and color stability of bulk-fill resin composites
Vieira-Junior WF et al. Effect of charcoal-containing toothpastes on roughness and
color stability of bulk-fill resin composites
INTRODUCTION
Charcoal is a carbon compound produced by
burning materials, such as coconut shells, nutshells,
bamboo, animal bones, and other sources [1].
It has been used for medical purposes since Ancient
Greece [2,3]. Currently, charcoal or activated
charcoal has been used in dentistry, marketed as
toothpaste or powder for toothbrushing, primarily
due to its purported whitening properties [3] enabled
by its potential capacity to adsorb pigments [4].
Nevertheless, this whitening effect has not been
reported in previous studies [5-8]. Many digital
inuencers advertise these products, and encourage
their followers to purchase them. Such products
are often available on e-commerce platforms at
lower prices, and can easily be obtained. In recent
years, well-established oral care manufacturers
have also introduced their versions of products
containing whitening agents [1,9,10], although
there are few investigations regarding their safety
or effectiveness.
As a result, some adverse effects caused
by these products have already been reported,
such as abrasive tooth wear, increased dentin
hypersensitivity, and degradation of restorative
materials [3,8,11]. Thus, just like common
abrasives, charcoal can have abrasive properties
that vary among manufacturers [1], or that can
even involve non-controlled manufacturing of its
particles. Among the toothpastes commercially
available to consumers, whitening toothpastes
containing conventional abrasives can alter
roughness [12], and cause color changes in
conventional resin composites, depending on the
type of toothpaste and resin composite [13-15].
However, studies investigating the effects of
charcoal-based toothpastes on the properties of
bulk-ll resin composites are very scarce.
Bulk-ll resin composites have emerged on
the market to reduce the effects of polymerization
shrinkage associated with incremental techniques,
thereby also reducing clinical time by increasing
the depth of cure, and enabling the insertion of
larger increments [16,17]. Categorically, bulk-ll
composites can be: I) applied as a restoration base
that must be overlaid with a conventional resin
composite; or II) applied as a single body (full-
body), used in a single increment (4-5 mm) [16].
High-viscosity bulk-ll composites represent resin
composites with the highest inorganic content,
microhardness, and wear resistance [16,17],
thus providing them with adequate properties for
exposure to the oral environment, and for use in
direct restorations in posterior teeth. The good
clinical performance of specific resin-based
materials requires enhancing the parameters
that mediate clinical success over time, such as
the surface characteristics, and the color stability
of the material and restoration [18]. However,
there is a lack of investigations into the resistance
of these bulk-ll resin composites to roughness
and color alterations resulting from exposure to
conventional or charcoal-containing toothpastes.
Therefore, studies are needed to investigate
the possible effects of toothpastes containing
charcoal on hygiene and oral health, and on
the properties of dental hard tissues and dental
materials. The foremost concern warranting further
discussion is the safety of these products, especially
because consumers are using these charcoal-based
products without knowing the risks to the oral
environment [19]. Thus, the null hypotheses were
that toothpastes containing charcoal do not differ
from conventional/regular toothpaste regarding 1)
surface roughness and 2) color change, and that
(3) the nanohybrid and nanolled bulk-ll resin
composites studied do not differ when brushed with
the same type of toothpaste.
MATERIAL & METHODS
ΔSGU), com α=0,05. Resultados: Independentemente do dentifrício, a Ra aumentou após a escovação, mas
com valores signicativamente maiores para a NH do que para a NP (p = 0,0001). Os valores de L* diminuíram
signicativamente (p = 0,0027) após escovação com Black is White. NP mostrou maiores valores de ΔE00 após
escovação com os DCCs comparada ao dentifrício regular. Adicionalmente, NH exibiu maiores valores de ΔEab e
ΔE00 quando exposta ao dentifrício Black is White comparada aos outros dentifrícios (p < 0,0001). Conclusão:
A alteração de rugosidade não foi mediada pela tipo de dentifrício. Entretanto, os DCCs foram capazes de alterar
as propriedades ópticas das RC bulk-ll, com efeitos mais potencializados com o dentifrício Black is White.
PALAVRAS-CHAVE
Carvão ativado; Cor; Cremes dentais; Escovação; Resinas compostas.
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Braz Dent Sci 2024 July/Sept;27 (3): e4414
Vieira-Junior WF et al.
Effect of charcoal-containing toothpastes on roughness and color stability of bulk-fill resin composites
Vieira-Junior WF et al. Effect of charcoal-containing toothpastes on roughness and
color stability of bulk-fill resin composites
Study design
The present study was designed using a
factorial scheme, considering the following
factors: I) resin composite (experimental unit,
Ø 6 mm; n = 10): nanofilled bulk-fill resin
composite (Filtek One Bulk-Fill, 3M Oral Care),
and nanohybrid bulk-ll resin composite (Aura
Bulk-Fill, SDI); II) toothpaste: regular toothpaste
containing either silica (Total 12 [RT], Colgate-
Palmolive – pH: 8.29); or charcoal (Black is
White [BWC], Curaprox – pH: 6.64; Luminous
White Activated Charcoal [LWC], Colgate-
Palmolive – pH: 7.88; and 3D White Mineral
Clean [WMC], Oral-B – pH: 7.60); and III) time
points: initial (baseline) and after cycling in the
brushing machine (10,000 cycles). The dependent
variables were surface roughness (Ra) and color
(Vita Classical, L*, a*, and b* coordinates, ΔEab
and ∆E00).
Sample size was calculated using G*Power
3.1.5 software (Heine, Universität Dusseldorf,
Germany), considering the following parameters:
α = 0.05, 1-β = 0.9, and size effect and standard
deviation calculated according to a pilot study
(n = 3). The results indicated that 7 samples
would be needed to determine the roughness
variable (ΔRa), and 3 samples for the color
analyses (ΔE00). Therefore, the study was
conducted considering n = 10.
Sample preparation
Filtek One Bulk-Fill (3M Oral Care) and
Aura Bulk-Fill (SDI) resin composites were
inserted in a single increment in a rubber elastic
matrix (6 × 2 mm), over a microscope glass
slide. After insertion, the specimen was covered
with a mylar strip and another microscope glass
slide. Next, a 500 g weight was applied over it
for 10 seconds to remove any bubbles that might
have been created during the increment insertion.
The specimen was then light-cured using an LED
device (Valo, Ultradent, South Jordan, UT, USA)
for 20 seconds (standard mode, 1000 mW/cm2).
After the specimen was cured, it was removed
from the matrix, and the excess was removed
with a scalpel blade. The composition and
classication of the evaluated resin composites
are presented in Table I.
Experimental groups and simulated brushing
The specimens were submitted to initial color
and roughness analyses, and then to simulated
brushing in an automatic machine (MEV 3T –
10 XY, Odeme Dental Research, Luzerna, SC,
Brazil) with the toothpastes presented in Table II.
The specimens were fixed individually in the
brushing machine with a hot-melt adhesive,
so that their surface remained parallel to the
toothbrushes (Oral-B Indicator 40 soft, Gillette
do Brasil, Manaus, AM, Brazil). Each specimen
was randomly assigned to a group, and exposed
individually to a certain toothpaste.
Brushing was performed with 10 mL of the
slurry created by the mixture of the toothpaste
and distilled water, in a 1:3 ratio by weight,
with a 200 g axial load, in a zig-zag pattern
(150 oscillations/min). The specimens were
submitted to 10,000 cycles, equivalent to one year
of use of the toothpaste [20]. After the specimens
were subjected to the brushing cycling, they were
rinsed in distilled water for 30 seconds, stored,
and once again submitted to color and roughness
analysis.
Surface roughness analysis
Surface roughness analysis of the specimens
was performed using a roughness tester (Surftest
SJ-210, Mitutoyo Corporation, Kanagawa, Japan)
at the following time points: initial (baseline)
and after automatic brushing. Each reading
Table I - Composition, classification, and manufacturers of resin composites1
Resin composite Classification Manufacturer Composition
Filtek One Bulk- Fill
Shade: A1 Nanofilled Bulk-fill 3M, St. Paul,
Minnesota, USA
Aromatic urethane dimethacrylate, UDMA, DDDMA, water,
silane treated ceramic (60-70% in weight); silane treated silica
(1-10% in weight); silane treated zirconia (<5% in weight),
ytterbium fluoride.
Aura Bulk-Fill
Shade: BKF (universal) Nanohybrid Bulk-fill SDI, Bayswater,
Victoria, Australia
UDMA, Bis-EMA, Bis-GMA, TEGDMA, amorphous SiO2, barium
aluminosilicate glass, prepolymerized filler particles.
1 The composition is presented in the MSDS (Material Safety Data Sheet) provided by the manufacturers. Abbreviations: UDMA, urethane
dimethacrylate; DDDMA, 1,12-dodecanediol dimethacrylate; Bis-EMA, bisphenol-A hexaethoxylated dimethacrylate; Bis-GMA, bisphenol-A
glycidyl methacrylate; TEGDMA, triethylene glycol dimethacrylate.
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Vieira-Junior WF et al.
Effect of charcoal-containing toothpastes on roughness and color stability of bulk-fill resin composites
Vieira-Junior WF et al. Effect of charcoal-containing toothpastes on roughness and
color stability of bulk-fill resin composites
presented an average roughness (Ra, µm) with
a 0.25 mm cut-off, at a 0.25 mm/s speed, and a
distance length of 1.25 mm. Three readings were
performed on each surface; the needle always
passed through the geometric center of the
specimen in three different positions, obtained
after rotating the base at 120°. Thus, the average
roughness of each sample was obtained by the
mean of the three readings.
Color analyses
Color analyses for each sample were
performed initially (baseline) and after brushing
with the toothpastes in a brushing machine, using
a digital spectrophotometer (VITA Easyshade,
VITA Zahnfabrik, Bad Säckingen, Germany),
a white background, and an ambient light
patterning box [21]. The spectrophotometer
was calibrated prior to use according to the
manufacturer’s instructions. The results were
quantied on the Vita Classical scale and the
CIEL*a*b* system coordinates. Vita Classical data
were categorized into scores (shade guide units,
SGU) based on the degree of luminosity [22],
and the variation among these scores was then
determined (ΔSGU). The CIEL*a*b* system was
employed to determine the values for the L*, a*,
and b* coordinates. The ΔEab and ΔE00 values
indicated the overall color difference, calculated
as follows:
( ) ( ) ( )
222
* * *
ab
E Lab∆ =√∆ +∆ +∆
(I)
( )
( )
( )
( )
( )
2
2
00
2
´/ ´/
´/ ´/ ´/(
LL CC
HH CC HH
E LkS Ck S
HkS RT CkS H kS
∆ =√∆ + ∆ +
∆ +∆ ∆
(II)
The ΔE00 values were calculated
sequentially [23], and then compared with the
acceptability/perceptibility threshold values [24].
Statistical analysis
The roughness (Ra) data and the L* and
b* values were analyzed using generalized
linear models for repeated measures over time.
These analyses considered the effects of resin
composite, toothpaste, and time, along with their
double and triple interactions. The general color
change values (ΔEab and ΔE00) were analyzed
Table II - Information on commercial toothpastes used in the present study according to the manufacturer1
Toothpaste Code Classification Manufacturer Composition
Colgate Total 12
RT Regular
toothpaste
Colgate-Palmolive
(São Paulo, Brazil)
Sodium fluoride (1450 ppm), cellulose gum, zinc
oxide, poloxamer 407, tetrasodium pyrophosphate,
zinc citrate, benzyl alcohol, cocamidopropyl betaine,
xanthan gum, sodium saccharin, phosphoric acid,
sucralose, titanium dioxide (CI 77891)
pH: 8.29
Curaprox® Black is White
BWC
Charcoal-
containing
toothpaste
Curaprox (Kriens,
Switzerland)
Sodium monofluorophosphate (950 ppm), water,
sorbitol, glycerin, hydrated silica, charcoal powder,
flavor (aroma), decyl glucoside, cocamidopropyl
betaine, tocopherol, mica, xanthan gum,
hydroxyapatite, titanium dioxide, microcrystalline
cellulose, maltodextrin, potassium acesulfame, sodium
benzoate, potassium chloride, potassium sorbate,
menthyl lactate, methyl diisopropyl propionamide,
ethyl menthane carboxamide, zea mays starch, stearic
acid, cetearyl alcohol, citrus lemon peel oil, citric acid,
lactoperoxidase, glucose oxidase, amyloglucosidase,
tin oxide, sodium bisulfite, hydrogenated lecithin,
limonene, CI 75810, CI 77289
pH: 6.64
Colgate® Luminous White
Activated Charcoal
LWC
Charcoal-
containing
toothpaste
Colgate-Palmolive
(São Paulo, Brazil)
Sodium monofluorophosphate (1000 ppm), CI
77266 (charcoal powder), CI 16035, CI 42090, CI
19140, water, hydrated silica, sorbitol, calcium
pyrophosphate, glycerin, peg-12, pentasodium
triphosphate, tetrapotassium pyrophosphate, flavor
(aroma), sodium lauryl sulfate, cellulose gum, sodium
saccharin, xanthan gum, cocamidopropyl betaine,
limonene
pH: 7.88
Oral-B® 3D White Mineral
Clean
WMC
Charcoal-
containing
toothpaste
Procter & Gamble
(São Paulo, Brazil)
Sodium fluoride (1100 ppm), water, sorbitol, hydrated
silica, disodium pyrophosphate, sodium lauryl sulfate,
cellulose gum, sodium hydroxide aroma, sodium
saccharin, carbomer, charcoal powder, mica, limonene,
sucralose, dioxide titanium 80, polysorbate
pH: 7.60
1The slurry pH was evaluated in triplicate using a pH meter (MPA 210, MS Tecnopon Instrumentação, Piracicaba, Brazil).
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Vieira-Junior WF et al.
Effect of charcoal-containing toothpastes on roughness and color stability of bulk-fill resin composites
Vieira-Junior WF et al. Effect of charcoal-containing toothpastes on roughness and
color stability of bulk-fill resin composites
using generalized linear models, considering the
effects of resin composite and toothpaste, as well
as their interaction. The data for the a* coordinate
and Vita scale scores (ΔSGU) were analyzed
using the Mann-Whitney test for comparisons
between the resin composites, the Kruskal-Wallis
and the Dunn tests for comparisons among the
toothpastes, and the paired Wilcoxon tests for
comparisons over time. All the analyses were
performed using the R program (R Core Team,
Vienna, Austria), with a signicance level set at
5%.
RESULTS
The roughness results are presented in
Table III. The roughness values increased
significantly in all the groups after brushing
(p = 0.0001); however, there was no signicant
difference among the toothpastes (p = 0.4491).
At the initial time point (baseline), the roughness
was significantly higher (p = 0.0001) in the
nanolled (Filtek One) than the nanohybrid resin
composite (Aura). After brushing, the roughness
values were signicantly higher (p = 0.0001)
in the nanohybrid (Aura) than the nanolled
(Filtek One) resin composite, regardless of the
toothpaste.
The L* coordinate results are presented in
Table IV. At baseline, the nanolled bulk-ll resin
composite (Filtek One) presented signicantly
higher L* values than the nanohybrid bulk-
fill resin composite (p = 0.0027). Both resin
composites indicated a signicant increase in the
L* values (p < 0.0001) after brushing with the
RT and charcoal-containing toothpastes (LWC
and WMC). When brushed with BWC charcoal
toothpaste, the resin composites presented a
signicant decrease in L* values (p < 0.0001).
After brushing, the nanofilled bulk-fill resin
composite (Filtek One) presented higher L*
values in the group brushed with LWC, and lower
L* values in the BWC than the RT and WMC
groups (p < 0.0001). As for the nanohybrid bulk-
ll resin composite (Aura), the L* values after
brushing were signicantly higher for the RT and
LWC groups than the BWC group (p < 0.0001).
The results of the a* coordinate are presented
in Table IV. The a* values were significantly
more negative (p < 0.05) in the nanohybrid
than the nanolled resin composite (p < 0.05).
After brushing, there was a signicant increase
in the a* values in all the groups (Filtek One,
p = 0.03; Aura, p < 0.01). The nanolled bulk-
fill resin composite presented more negative
a* values for BWC than WMC after brushing
(p = 0.005). In contrast, the nanohybrid bulk-
ll presented more negative a* values in the RT,
LWC, and WMC groups than the BWC group
after brushing (p < 0.0001). Considering the
b* results (Table IV), the nanofilled bulk-fill
resin composite presented signicantly higher
b* values at the initial time period than the
nanohybrid resin composite (p < 0.0001), and
signicantly lower b* values for WMC than the
other toothpastes after brushing (p < 0.0001).
As for the nanohybrid resin composite, the
b* values were significantly lower for WMC
(p < 0.05) after brushing, compared with the
other groups. There was a signicant decrease
Table III - Mean (standard deviation) surface roughness values (Ra, µm) according to the toothpaste, resin composite, and time
Resin composite Toothpaste
Time
Baseline After brushing
Nanofilled bulk fill
RT 0.11 (0.04) Ba 0.25 (0.14) Aa
BWC#0.10 (0.03) Ba 0.24 (0.05) Aa
LWC#0.11 (0.04) Ba 0.18 (0.08) Aa
WMC#0.10 (0.03) Ba 0.15 (0.06) Aa
Nanohybrid bulk fill
RT 0.08 (0.04) Ba* 0.32 (0.18) Aa*
BWC#0.07 (0.03) Ba* 0.26 (0.12) Aa*
LWC#0.08 (0.04) Ba* 0.23 (0.09) Aa*
WMC#0.08 (0.04) Ba* 0.26 (0.15) Aa*
#represents a charcoal-containing toothpaste. *indicates a statistical difference between the nanohybrid bulk-fill resin composite (Aura) and
nanofilled bulk-fill resin composite (Filtek One), under the same conditions of toothpaste and time (p < 0.05). Distinct letters (uppercase letters in
rows and lowercase letters in columns, comparing the toothpastes in each resin composite) indicate statistically significant differences (p < 0.05).
p-values: toothpaste = 0.6390; resin composite = 0.0955; time < 0.0001; toothpaste vs. resin composite = 0.4491; toothpaste vs. time = 0.3047;
resin composite vs. time = 0.0001; toothpaste vs. resin composite vs. time = 0.9956.
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Braz Dent Sci 2024 July/Sept;27 (3): e4414
Vieira-Junior WF et al.
Effect of charcoal-containing toothpastes on roughness and color stability of bulk-fill resin composites
Vieira-Junior WF et al. Effect of charcoal-containing toothpastes on roughness and
color stability of bulk-fill resin composites
in the b* values in all the groups after brushing
(p < 0.0001).
Overall color change data are presented in
Figures 1 (ΔEab) and Figure 2 (ΔE00). The ΔEab
values for the nanolled bulk-ll resin composite
were significantly higher for BWC and WMC
(charcoal toothpastes) than RT (p < 0.0001).
As for the nanohybrid resin composite, ΔEab
was signicantly higher for BWC than for the
other toothpastes (p < 0.0001). Comparatively,
the ΔE00 values for the nanolled bulk-ll resin
composite were signicantly lower for RT than
for the charcoal toothpastes (p < 0.05), and the
ΔE00 values for the nanohybrid resin composite
were signicantly higher for BWC than for the
other toothpastes (p < 0.0001).
The variation in the shade guide unit
(ΔSGU) results is presented in Table V. When
the brushing was performed with RT, LWC
and WMC, the scores decreased more for
the nanofilled bulk-fill than the nanohybrid
resin composite (p = 0.0002). Regarding
the nanofilled resin composite, the scores
decreased more for LWC and WMC toothpastes
than the BWC toothpaste (p < 0.0001). As for
the nanohybrid resin composite, the scores
decreased more for RT, LWC, and WMC than
for BWC (p < 0.0001).
Table IV - Mean (standard deviation) or median (minimum; maximum) of L*, a*, and b* values, according to the toothpaste, resin composite,
and time
Variable Resin composite Toothpaste
Time
Baseline After brushing
L*
Nanofilled bulk-fill
RT 84.97 (1.02) Ba 85.67 (1.10) Ab
BWC#84.96 (0.84) Aa 83.00 (0.84) Bc
LWC#85.22 (0.80) Ba 87.07 (0.77) Aa
WMC#85.38 (1.00) Ba 86.18 (1.04) Ab
Nanohybrid bulk-fill
RT 82.18 (1.07) Ba* 84.42 (0.94) Aa*
BWC#82.45 (0.91) Aa* 78.70 (1.77) Bc*
LWC#82.51 (0.71) Ba* 84.88 (0.81) Aa*
WMC#82.31 (1.06) Ba* 83.48 (0.80) Ab*
a*
Nanofilled bulk-fill
RT -0.1 (-0.6; 0.0) Ba 0 (-0.4; 0.01) Aab
BWC#-0.25 (-0.6; 0.1) Ba -0.1 (-0.8; 0) Ab
LWC#-0.2 (-0.3; 0.1) Ba -0.1 (-0.3; 0.1) Aab
WMC#-0.15 (-0.4; 0.2) Ba 0.1 (-0.1; 0.2) Aa
Nanohybrid bulk-fill
RT -0.9 (-1; -0.7) Ba* -0.7 (-0.8; -0.5) Ab*
BWC#-0.85 (-1.1; -0.4) Ba* -0.35 (-0.6; -0.1) Aa*
LWC#-0.9 (-1; -0.6) Ba* -0.65 (-0.7; -0.5) Ab*
WMC#-0.9 (-1.1; -0.8) Ba* -0.7 (-0.9; -0.5) Ab*
b*
Nanofilled bulk-fill
RT 20.37 (0.80) Aa 18.26 (0.62) Ba
BWC#20.23 (2.04) Aa 18.53 (0.44) Ba
LWC#20.67 (0.63) Aa 18.51 (0.49) Ba
WMC#20.57 (0.34) Aa 17.02 (0.65) Bb
Nanohybrid bulk-fill
RT 16.71 (0.38) Aa* 15.78 (0.56) Ba*
BWC#16.59 (0.57) Aa* 15.39 (0.63) Bab*
LWC#16.83 (0.65) Aa* 15.33 (0.33) Bb*
WMC#17.01 (0.54) Aa* 14.55 (0.67) Bc*
#represents a charcoal-containing toothpaste. * indicates a statistical difference between the nanohybrid bulk-fill resin composite (Aura) and
the nanofilled bulk-fill resin composite (Filtek One), under the same conditions of toothpaste and time (p < 0.05). Distinct letters (uppercase
letters in rows and lowercase letters in columns, comparing toothpaste in each resin composite) indicate statistically significant differences (p
< 0.05). Considering the variables and p values, L* coordinate: toothpaste < 0.0001, resin composite < 0.0001, time = 0.0023, toothpaste vs.
resin composite = 0.0517, toothpaste vs. time < 0.0001, resin composite vs. time = 0.5601, toothpaste vs. resin composite vs. time = 0.0027.
The a* coordinate: Filtek One (baseline = 0.2822, after brushing = 0.0051, comparing the time points = 0.03, and other comparisons < 0.05)
and Aura (baseline = 0.5180, after brushing < 0.0001, and comparing the time points < 0.01). The b* coordinate: toothpaste = 0.0047, resin
composite < 0.0001, time < 0.0001, toothpaste vs. resin composite = 0.4628, toothpaste vs. time < 0.0001, resin composite vs. time = 0.3708,
and toothpaste vs. resin composite vs. time = 0.1270.
7
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Vieira-Junior WF et al.
Effect of charcoal-containing toothpastes on roughness and color stability of bulk-fill resin composites
Vieira-Junior WF et al. Effect of charcoal-containing toothpastes on roughness and
color stability of bulk-fill resin composites
Table V - Median (maximum; minimum value) color change caused by the toothpaste on the resin composite, as quantified by the Vita scale (ΔSGU)
Toothpaste
Resin composite
p-value
Nanofilled bulk-fill Nanohybrid bulk-fill
RT -2 (-3; -2) Aab -1 (-1; -1) Bb
0.0002
BWC#0 (0; 3) Aa 0 (-1; 1) Aa
0.9699
LWC#-3 (-3; -2) Ab -1 (-1; 0) Bb
0.0002
WMC#-3 (-3; -3) Ab -1 (-1; -1) Bb
0.0002
p-value <0.0001 <0.0001
# represents a charcoal-containing toothpaste. Distinct letters (uppercase letters in rows and lowercase letters in columns) indicate statistically
significant differences (p < 0.05).
Figure 1 - Box-plot of the ΔEab values according to the toothpaste and the resin composite. # represents a charcoal-containing toothpaste.
Distinct uppercase letters indicate statistically significant differences between the resin composites (p < 0.05). Distinct lowercase letters
indicate statistically significant differences among the toothpastes. p-values: p(toothpaste) < 0.0001; p(resin composite) = 0.6705; p(toothpaste
vs. resin composite) = 0.1307.
Figure 2 - Box-plot of the ΔE00 values according to the toothpaste and the resin composite. # represents a charcoal-containing toothpaste.
Distinct uppercase letters indicate statistically significant differences between the resin composites (p < 0.05). Distinct lowercase letters
indicate statistically significant differences among the toothpastes. p-values: p(toothpaste) < 0.0001; p(resin composite) = 0.0229; p(toothpaste
vs. resin composite) = 0.0794.
8
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Vieira-Junior WF et al.
Effect of charcoal-containing toothpastes on roughness and color stability of bulk-fill resin composites
Vieira-Junior WF et al. Effect of charcoal-containing toothpastes on roughness and
color stability of bulk-fill resin composites
DISCUSSION
Charcoal-based products are sold using
different marketing strategies, and consumers
and patients are exposed to abrasive toothpastes
and powders without knowing the health
risks [19]. Bearing this in mind, the present
study investigated the potential effects of these
toothpastes on bulk-ll resin composites, and
restorative materials commonly used in dental
practice. Considering the results found, the color
stability was mediated by the toothpastes, but
the surface roughness was especially affected by
the composition of the bulk-ll resin composites.
Therefore, the null hypothesis was rejected.
The clinically acceptable performance of
certain resin-based materials requires analyzing
some parameters that mediate clinical success
over time, such as the surface characteristics and
color stability of the material and restoration [18].
The roughness results are corroborated by
Shimokawa et al. [25], who reported elevated
roughness values for the Aura bulk-fill resin
composite after exposure to RT. The resin
composite composition impacts wear resistance
and surface characteristics, and conventional
nanohybrid resin composites are more susceptible
to roughness and surface morphology changes than
nanolled resin composites [26,27]. In addition
to its nanohybrid characteristics, Aura Bulk-Fill
presents irregular matrix-dispersed clusters [28],
monomeric alteration, and incorporation of pre-
polymerized particles in its composition, all of
which could intensify its surface changes [29].
The roughness values were not mediated
by the type of toothpaste, and no differences
were found between the RT and the charcoal
toothpastes [30]. However, the higher number of
abrasive particles in the whitening toothpastes than
the RTs could explain the color changes [14,31].
The results showed higher roughness and color
changes (ΔE00 - RT and BWC) in the nanohybrid
bulk-ll resin composite (Aura), compared with
the nanolled composite (Filtek One), bearing in
mind that the latter is composed of a nanosized
filler and nanoclusters, which present better
physical properties and surface smoothness for
better wear resistance to abrasion [14,32,33].
The composition of the tested materials also
impacted the initial values of the color coordinates
and the surface roughness, thus corroborating
previous studies [25,29,34]. Aura resin composite
is marketed in a non-VITA shade (BFK, universal),
while Filtek One is offered in a VITA shade
(A1). As a result, initial differences between the
composites can be expected due to variations
in pigment incorporation and the translucency
modiers specic to each brand. Filtek One, for
instance, appears to be more saturated with white
pigments, as indicated by the L* values. Moreover,
initial differences in roughness can be associated
with the specimen preparation, since the specimens
were prepared using a polyester strip [35], whereas
the materials exhibited surface characteristics based
on their organic matrix (Table I).
According to the color results, the charcoal
toothpastes promoted a general color change,
specifically in the CIEL*a*b* coordinates at
different intensities, thus indicating the rejection
of the null hypothesis. In the CIEL*a*b* system,
the L* coordinate indicates luminosity (black-
white axis; 0 – 100), the a* coordinate represents
saturation at the green (-) and red (+) axis, and
the b* coordinate, at the blue (-) and yellow (+)
axis. The toothpaste that presented the highest
color changes was BWC, with a decrease in L*
values (towards black) and higher values of color
change (ΔEab and ΔE00) than RT.
However, all the evaluated toothpastes
containing charcoal promoted color changes
compared with RT, for at least one of the
studied optical variables, regardless of the resin
composite. Considering the general color change
thresholds [24], all the toothpastes promoted
clinically perceptible color changes (ΔEab > 1.2;
ΔE00 > 0.8), but only the toothpastes containing
charcoal surpassed the suggested acceptability
limits for ΔEab (> 2.7) and ΔE00 (> 1.8), except
the nanolled bulk-ll resin composite (Filtek
One) exposed to LWC (ΔE00 = 1.7).
The color results are in line with what
was suggested by a previous study [36], which
presented color change for a conventional resin
composite exposed to toothpastes and powders
containing charcoal. Although the importance of
color in posterior restorations is seldom discussed,
marginal and bulk discoloration represents
up to 18% of the reasons for substitution of
restorations [37]. Considering that no differences
were found between the toothpastes regarding the
surface roughness pattern, it could be hypothesized
that the color changes of the resin composites
could have been caused by the penetration of
external pigments from the toothpastes by charcoal
9
Braz Dent Sci 2024 July/Sept;27 (3): e4414
Vieira-Junior WF et al.
Effect of charcoal-containing toothpastes on roughness and color stability of bulk-fill resin composites
Vieira-Junior WF et al. Effect of charcoal-containing toothpastes on roughness and
color stability of bulk-fill resin composites
solubilization, together with some degradation or
pigment incorporation on the polymeric chain.
The pigmentation seems to be mediated
by the toothpaste composition, manufacture of
the abrasive particle, and concentration of these
compounds in the toothpaste [30, 31], whereas
charcoal-containing toothpastes had an impact
on the color of the evaluated resin composites in
different intensities. The most signicant changes
in the color of the materials were caused by
BWC, a toothpaste free of sodium lauryl sulfate
(Table II), a common surfactant [38]. New studies
are recommended to help better understand their
mode of action, especially over the potential of
these toothpastes to remove pigments inherent
to the resin composite itself, represented by the
alterations found in the b* coordinate.
The ndings of the present study add important
considerations to previous discussions [1,3,9] on
the general use of products containing charcoal
and their effects on restorative materials. Although
this was a controlled in vitro study, the results
should be interpreted cautiously, and cannot be
directly extrapolated to a clinical context, since
some effects cannot be fully replicated due to
the overly rigorous nature of the protocols used.
Further studies employing methodologies, such
as an optical prolometer or in vivo assessments,
are essential to fully investigate the effects of these
toothpastes on bulk-ll resin composites.
CONCLUSION
The greatest changes in roughness were found
for the nanohybrid bulk-ll resin composite (Aura,
SDI), regardless of the toothpaste used. Charcoal-
containing toothpastes did not intensify the change
in roughness differently from regular toothpastes.
However, they did change the optical properties
of the bulk-ll resin composites, in that the effects
were more enhanced when the resin composites
were brushed with Black is White toothpaste.
Author’s Contributions
WFVJ: contributed with the conceptualization,
data curation, writing – original draft preparation,
supervision and project administration. RQC:
contributed with the methodology, writing – original
draft preparation, validation. and investigation.
LSB: contributed with the writing – review &
editing, formal analysis, and visualization. MMM:
contributed with the methodology, data curation
and investigation. CPT: contributed with the
conceptualization, formal analysis, and validation.
FMGF: contributed with the conceptualization, data
curation and validation. NIPP: contributed with the
resources, writing – review & editing, validation
and visualization. RTB: contributed with the
conceptualization, supervision and investigation.
Conict of Interest
The authors have no conicts of interest to
declare.
Funding
This research did not receive any specic
grant from funding agencies in the public,
commercial, or not-for-prot sectors.
Regulatory Statement
This study was exempted from review by the
local ethics committee, since it did not involve
the participation of any volunteers, or the use of
any human material.
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Braz Dent Sci 2024 July/Sept;27 (3): e4414
Vieira-Junior WF et al.
Effect of charcoal-containing toothpastes on roughness and color stability of bulk-fill resin composites
Vieira-Junior WF et al. Effect of charcoal-containing toothpastes on roughness and
color stability of bulk-fill resin composites
Waldemir Francisco Vieira-Junior
(Corresponding address)
UNICAMP, Faculdade de Odontologia de Piracicaba, Departamento
de Odontologia Restauradora, Piracicaba, SP, Brazil.
Email: waljr@unicamp.br
Date submitted: 2024 June 20
Accept submission: 2024 Aug 20
