Key words:
Light emitting diode-device - nonabrasive toothpaste - photoactivation - tooth color
- tooth whitening
INTRODUCTION
White, immaculate teeth are an important consumer desire worldwide. Therefore, discolored
teeth represent an esthetic problem, particularly when affecting the maxillary anterior
teeth.[1] The desire is highlighted by various over-the-counter (OTC) whitening products available
on the market as toothpaste or mouthwashes.[2]
OTC tooth whitening products usually contain low levels of whitening agents such as
3%-6% hydrogen peroxide and abrasives, as well as chemicals to maximize cleaning.[3]
[4]
[5]
[6]
[7]
[8]
[9]
[3] They are usually self-applied to the teeth via gum shields, strips, or other. Even
though efficacious, their prolonged use may also lead to an undesirable increase of
tooth surface wear, affecting not only sound enamel surfaces but also, and more significantly,
mineralizable incipient caries, and erosion lesions.[11]
[12]
[13] A wide range of tooth whitening toothpaste formulations is available. These formulations
contain plant extracts such as papain, bromelain, extracts from arctic lichen or the
recently developed agent with optical properties, blue covarine and are generally
considered less aggressive to the teeth.[10]
[14]
[15]
One method for assessing color of teeth is chromametry, based on the color expression
regarding the Commission internationale de l’Eclairage (CIE) Lab color space. This
space represents a uniform color space, with equal distances corresponding to equally
perceived color differences. In this three-dimensional color space, the three axes
are L*, a* and b*.
A very convenient method to measure tooth color consists in the use of noncontact
camera-based digital imaging and analysis systems.[16]
[17]
[18]
[19]
[20] For this, an image of the anterior teeth is captured under controlled light conditions
by a digital camera, using suitable calibration tiles or standards, and then subsequently
analyzed via computer software to determine the color of the individual teeth, expressing
them regarding CIE Lab values.[13] A further sensitive parameter used to assess the whiteness of teeth is the whiteness
index (WIO).[21]
The objective of this study was to assess the onset time of a commercially available
nonabrasive photoactivated tooth-whitening paste (BlanX® White Shock®, Coswell s.p.a,
Funo, Italy) containing arctic lichen (Cetraria islandica), titanium dioxide and hydroxyapatite as an activator (Actilux® Incos Cosmeceutica
Industriale s. r. l., Funo, Italy) and an adjunctively-used light emitting diode (LED)
device compared to the tooth-whitening paste alone, using an imaging and analysis
method.
MATERIALS AND METHODS
Settings
This randomized, investigator-blind study was conducted in February 2016 at one study
site in Hamburg, Germany.
The study received ethics committee approval (Freiburger ethics commission international,
code 017/1070) and was conducted according to the main principles of good clinical
practices and by the principles of the Declaration of Helsinki and local legal requirements
for the conduct of cosmetic studies.
Each subject who participated in this study was informed verbally and in written form
about the study and signed the informed consent form before inclusion and before any
study procedure.
Study population
Suitable participants for this study had to be aged between 18 and 70 years and had
to have eight intact, naturally healthy, slightly yellow front teeth with a regular
stain. Moreover, participants had to respect average oral hygiene, defined as twice-daily
brushing of the teeth. Pregnant or lactating women, participants addicted to drugs
or alcohol, with a known acquired immunodeficiency syndrome or hepatitis infection,
or a known allergy to one of the compounds of the toothpaste, or who were wearing
tooth jewelry, fixed braces on or oral piercings near the front teeth were excluded
from this study. Furthermore, participants with an ongoing dental or any other medical
treatment of the oral cavity, or participants who had undergone a tooth whitening
procedure within 6 months prior to the start of the study or during the study, or
who had an antibacterial treatment of the oral cavity 2 weeks prior to or during the
study, were not allowed to participate.
Procedures
Participants who signed the informed consent attended three study visits (day 1, 8
and 15).
Baseline assessments
At day 1/baseline, participants were asked to brush their teeth with their own toothbrush
and toothpaste. A dentist assessed their eligibility according to the inclusion and
exclusion criteria. Participants were asked not to use any other cosmetic tooth whitening
products during the study. After the first brushing of the teeth, photographs of the
four anterior front teeth were taken.
Product use
Participants were randomized at day 1 to either use the toothpaste alone or together
with the LED device. Participants received the toothpaste and a toothbrush (manual,
medium softness) for the duration of the study and were not allowed to use any other
oral hygiene product, including toothpaste, chewing gum, mouthwash, or spray. Participants
were instructed to apply 1 cm of the test toothpaste to the provided brush and to
brush their teeth for 2 min according to their usual brushing habits. After rinsing
their mouth, participants randomized into the toothpaste-plus-LED group were instructed
to hold the device in front of their front teeth for 3 min, at a distance of approximately
3 cm. The first application of the test products took place in the morning of day
1 at the study site under the supervision of a technician. Then, the application was
performed by the participants twice daily (in the morning and the evening) at home.
On day 8 and 15, participants were asked to use the test toothpaste and LED device
as described above at the study site before the image was taken.
Efficacy and safety assessments
Standardized photographs of the four anterior teeth were taken on day 1 (before use
of the test products), day 8 and 15 in a photo studio specifically designed for high
definition clinical photography (USR-CliP). A camera with a high resolution 50 megapixels
(H5D-50c, Hasselblad, Göteborg, Sweden) and a professional flash system containing
a Broncolor Scoro A2 flash generator, two Broncolor Picolight flashes at the sides
and a central Broncolor ringflash C (Bron Elektronik AG Allschwil, Switzerland) was
used to homogeneously illuminate the front teeth. For reproducible positioning of
volunteers, a chin rest was used. The color of all visible front teeth was evaluated
individually with a specifically developed image analysis software (PIAS Teeth, proDERM
Image Analysis Software, proDERM, Hamburg, Germany). The average color was reported
as CIELAB (L*, a*, b*)-values and whiteness WIO was assessed.
WIO was calculated according to the following formula:
WIO = Y + 1075.012 (xn- x) +145.516 (yn- y).
Where Y is the luminance value and (x, y) and (xn, yn) are the chromaticity coordinates
of the sample and the reference white, respectively. A decrease of tooth color values
and an increase of WIO value can be interpreted as increased tooth whiteness.
Local tolerance was assessed at all the study visits.
Statistics
Due to the explorative character of the study, no adjustment for multiplicity was
made.
The comparison of assessment times was performed using a paired t-test on raw data
between day 1, day 8 and day 15 for a*, b* and WIO values. Comparisons between treatments
were made using independent t-tests for each assessment time point on differences
to baseline for a*, b * and WIO. Results of the questionnaires were analyzed using
a binomial test to assess the difference in frequencies of agreement and disagreement
answers.
A significance level of 0.05 (alpha) was chosen.
Statistical analyses were performed using commercially available statistics software
(SAS for Windows, version 9.4, SAS Institute Inc., Cary, USA).
RESULTS
Demographic data and baseline assessments
A total of 54 participants were enrolled in the study. Four withdrew: one due to a
test product-related adverse event and three for administration reasons. Data from
50 participants (15 [30%] male and 35 [70%] female participants with a mean age of
44.4 ± 12.8 years) were used for the data analysis. In each treatment group, 25 participants
completed the study.
Image analysis
Using the test toothpaste and the LED device resulted in a statistically significant
quicker onset of tooth whitening as early as day 8, compared to participants randomized
to the toothpaste-only group [Figure 1a-c].
Figure 1: (a) Mean values for tooth color (a*); *P = 0.001, **P < 0.001. (b) Mean values for tooth color (b*); *P = 0.004, **P = 0.016, ***P = 0.037. (c) Mean values for tooth whiteness (WIO); *P < 0.001, **P = 0.003, ***P < 0.001
In the group that used the LED device, a* and b* had significantly decreased versus
Day 1 (Δa*: -0.33, P = 0.001 and Δb*: -0.62, P = 0.004) while WIO had significantly increased ΔWIO: 5.53, P < 0.001) at day 8, sustaining until day 15 Δa*: -0.62, Δb*: -0.46, P = 0.037 and Δ WIO: 5.39, P < 0.001). For participants using the toothpaste only, significant results versus
day 1 were obtained only after 15 days Δa*: -0.73, P < 0.001, Δb*: -0.50, P = 0.016, Δ WIO: 5.85, P = 0.003). The difference between both study groups was not statistically significant,
at any time point or for any parameter.
Safety
Two participants reported an adverse event each. One (mild redness, itching and burning
on day 1 on the gum of the lower jaw) was considered as being probably related to
the tested toothpaste; the subject withdrew from the study. The second event was considered
unrelated to the test products; the subject continued the study.
DISCUSSION
The objective of this study was to assess the onset time of the whitening effect of
the activator-containing toothpaste combined with an LED device compared to that of
the whitening toothpaste alone.
Results from 50 participants showed that the additional use of a LED device significantly
improves the onset time of tooth whitening, compared to the classical use of the toothpaste:
a significant tooth whitening effect (P < 0.05) using the combined procedure was observed as early as 8 days after the start
of the study, sustaining until the end of the study on day 15. Conversely, a significant
difference of tooth whitening from day 1 using the toothpaste alone could only be
demonstrated after 15 days of continual, twice-daily use.
The cold-light bleaching technique assessed in the present study uses blue light (wavelength
between 480 nm and 520 nm). The device is equipped with a filter that excludes the
infrared (wavelength λ > 750 nm) and the harmful ultraviolet (λ < 380 nm). To the
best of our knowledge, only one in vitro study using a combined use of a LED device and a tooth whitening preparation containing
35% hydrogen peroxide was conducted.[22] Whitening results were promising, but the authors also observed a demineralization
in the enamel surface considered as being related to the use of an acidic peroxide-containing
bleaching agent but not related to the use of cold-light. Till date, no investigation
has been performed to assess in vivo the combined effect of cold blue light and a tooth whitening paste containing no
abrasive or aggressive bleaching or carbamide peroxide compounds such as hydrogen
peroxide.
The whitening toothpaste used in the present study does not contain any peroxide containing
agent, nor does it contain abrasive compounds. Its efficacy is based on the activator
(ActiluX®) and extracts from the arctic lichen Cetraria islandica. This lichen has been reported to have antioxidant, antimicrobial, genotoxic, and
anticancer properties.[23] In the oral cavity, extracts of Cetraria islandica limit naturally the proliferation of the buccal microbes, triggering buccal infections,
and extrinsic tooth staining.[24]
[25] ActiluX® is a patented combination of titanium dioxide and hydroxyapatite microcrystals.
Titanium dioxide is known as an intensely white pigment. It has a high refractive
index and is widely used in toothpaste formulations. Hydroxyapatite is a lattice of
calcium and is used in tooth and bone engineering.[26]
[27] Coating the teeth and slipping into tiny cracks, it breaks down in response to acid,
thereby protecting the tooth enamel from decay and cavities, and hence prevents from
sensitivity. In addition, it provides a source of calcium and phosphate ions which,
combined with fluoride, helps to remineralize the tooth surface. The combined use
of this novel toothpaste and of the LED device which activates the tooth whitening
effect of titanium dioxide, allows for a fast-onset of the tooth whitening effect,
while the sustained activity of hydroxyapatite and antimicrobial activity of Cetraria islandica improves tooth protection and the balance of the natural buccal microflora responsible
for the extrinsic staining. However, as is the case for every tooth whitening procedure,
the results obtained are not irreversible. Consumption of food or beverages, or medication,
may reinitiate tooth staining. Therefore, daily buccal care and limitation of extrinsic
stain triggers must be considered as prolonging the whitening results obtained.
CONCLUSION
Both tooth whitening methods have a whitening effect after 2 weeks of use confirming
the efficacy of the toothpaste. However, the onset of whitening was faster when using
the toothpaste combined with an LED device, thereby confirming the synergistic effect
of the LED device and the nonabrasive, activator-containing toothpaste.
Financial support and sponsorship
Nil.
