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This parallel, double-blind randomized clinical trial evaluated the 2-year bleaching efficacy and sensitivity produced by at-home (AH) and in-office (IO) bleaching therapies. 60 participants with tooth color darker than C2, without restorations in the anterior dentition and older than 18 years old, were randomly allocated into two groups to receive either IO with 35% hydrogen peroxide or AH with 16% carbamide peroxide. Color was recorded at baseline (BA); 1-week (1W); end of the treatment (ET); and 2 years (2Y) after bleaching, using the Vita Classical shade guide. The perception of TS was recorded on a 0-4 scale during and 2Y after bleaching. The variation in shade guide units (deltaSGU) from BA vs. 1W was compared to deltaSGU from BA vs. 2Y using paired t-test. The percentage of subjects who reported TS was evaluated by Fisher's exact test. The intensity of TS was evaluated by a Mann-Whitney test (alpha=0.05). Both bleaching techniques demonstrated equivalent and significant tooth color shade lightening. No significant color rebound occurred after 2Y for both techniques (P= 0.77 and 0.87, for AH and IO respectively). The absolute risk of TS was similar for IO and AH (P= 0.12), however the intensity of TS was significantly higher for IO (P= 0.001). No subjects reported sensitivity after 2Y.
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Research Article
Long-term efficacy of in-office and at-home bleaching:
A 2-year double-blind randomized clinical trial
BSTRACT: Purpose: This parallel, double-blind randomized clinical trial evaluated the 2-year bleaching efficacy and
sensitivity produced by at-home (AH) and in-office (IO) bleaching therapies. Methods: 60 participants with tooth color
darker than C2, without restorations in the anterior dentition and older than 18 years old, were randomly allocated into
two groups to receive either IO with 35% hydrogen peroxide or AH with 16% carbamide peroxide. Color was recorded
at baseline (BA); 1-week (1W); end of the treatment (ET); and 2 years (2Y) after bleaching, using the Vita Classical
shade guide. The perception of TS was recorded on a 0-4 scale during and 2Y after bleaching. The variation in shade
guide units ('SGU) from BA vs. 1W was compared to 'SGU from BA vs. 2Y using paired t-test. The percentage of
subjects who reported TS was evaluated by Fisher’s exact test. The intensity of TS was evaluated by a Mann-Whitney
test (=0.05). Results: Both bleaching techniques demonstrated equivalent and significant tooth color shade lightening.
No significant color rebound occurred after 2Y for both techniques (P= 0.77 and 0.87, for AH and IO respectively). The
absolute risk of TS was similar for IO and AH (P= 0.12), however the intensity of TS was significantly higher for IO
(P= 0.001). No subjects reported sensitivity after 2Y. (Am J Dent 2012:25:199-204).
LINICAL SIGNIFICANCE: In-office bleaching produced efficient and long-lasting whitening effect, as well as at-home
bleaching, however the in-office bleaching protocol showed a higher intensity of sensitivity.
: Prof. Alessandro Dourado Loguercio, Faculty of Dentistry, State University of Ponta Grossa, Av. Carlos
Cavalcanti, 4748 – Bloco M – Sala 64, Ponta Grossa, Paraná CEP 84030-900, Brazil. E-:
Improvements in the standard of living have increased the
number patients seeking cosmetic dentistry therapies. As whiter
teeth are perceived as being associated with health and beauty,
tooth bleaching has been widely performed by professionals for
treatment of discolored teeth. Compared with other restorative
treatments, such as porcelain veneers, crowns or composite
bonding, this treatment is a very conservative approach.
Different techniques are available for tooth bleaching.
Although at-home bleaching achieves a high success rate
it is the most widely taught bleaching technique in the USA,
some patients do not adapt well to the at-home protocol as they
prefer not to use a bleaching tray or do not want to wait 2-3
weeks to see the results of the treatment. Besides that, the
compliance of some patients to the daily use of a bleaching tray
that is not under the dentist’s control may increase the treatment
time and costs. In other clinical scenarios, such as the presence
of extensive tissue recession or deep unrestored abfraction
lesions, patients still need to be closely monitored.
For these
circumstances, the in-office bleaching protocol may be more
adequate, since it allows close dentist control, avoidance of
soft-tissue exposure and material ingestion, reduced total
treatment time and greater potential for immediate results
enhancing patient satisfaction and motivation.
Clinical trials
have compared the performance of high and
low-concentrated agents used for at-home or in-office tooth
bleaching and the majority has shown a similar whitening effect
for both concentrations and techniques. Nevertheless, the
incidence of tooth sensitivity or gingival irritation is more
common when the agent concentration is higher.
As patients look for an effective esthetic treatment, they
also expect that the treatment chosen will last for a long period
of time. Although a regression of color over time has been
reported for the at-home bleaching,
there is a general per-
ception among clinicians that at-home bleaching produces more
long-lasting results than in-office bleaching without a
substantial support of scientific evidence. Comparing 9-month
clinical longevity of both bleaching therapies did not detect any
significant difference among both protocols.
Few randomized
clinical trials
have evaluated the longevity of the whiten-
ing produced by in-office bleaching and those available report
only short-term results.
The present randomized clinical trial evaluated and com-
pared the 2-year longevity of bleaching efficacy and sensitivity
produced by at-home and in-office bleaching therapies. This
study was prepared according to the Consolidated Standards of
Reporting Trials (CONSORT) statement.
Materials and Methods
Experimental design - This clinical investigation was approved
under protocol number 08272/08 by the Institutional Review
Board of the local Ethics Committee of the State University of
Ponta Grossa, Brazil. Based on pre-established criteria, 60
volunteers were selected for this study. Two weeks before the
bleaching procedures, all the volunteers received a dental
screening and a dental prophylaxis with pumice and water in a
rubber cup. All subjects signed an informed consent form.
Study design - This was a randomized, double-blind, clinical
trial with an equal allocation rate to receive either one of two
treatments. The study took place in the School of Dentistry of
the State University of Ponta Grossa, Brazil, from October
2007 to August 2010.
Inclusion and exclusion criteria - Subjects included in this
clinical trial were at least 18 years old and had good general
200 Tay et al
and oral health. A total of 202 participants were examined to
check for the inclusion and exclusion criteria. Participants
needed to have six caries-free maxillary anterior teeth without
restorations on the labial surfaces, be willing to sign a consent
form and have central incisors determined to be shade C2 or
darker, according to a value-oriented shade guide [Vita Lumin
Vacuum (now marketed as Vita Classical
)]. Subjects were
excluded from the study if they had undergone tooth-whitening
procedures, had labial anterior restorations, were pregnant or
lactating, had severe internal tooth discoloration (such as
tetracycline stains, fluorosis, pulpless teeth), had bruxism habits
or had any other pathology that could cause sensitivity (such as
recession, dentin exposure).
Sample size calculation - Calculation of the sample size was
based on data resulting from previous in-office and at-home
bleaching studies.
For both bleaching protocols, the primary
outcome was the variation in shade guide units (SGU). A
sample size of 26 participants were required for both groups to
detect a difference of 1 SGU with a 90% statistical power
using a standard deviation of 1.5 with a significance level of
5%. In order to account for follow-up losses, 30 participants
were selected for each group.
Study intervention - Participants were randomly allocated into
two experimental groups (n = 30) according to the bleaching
technique: in-office or at-home bleaching. The simple random-
ization process was performed by computer-generated tables by
a third person not involved in the research protocol. Once the
participant was eligible for the procedure, and completed all
baseline assessments, the allocation assignment was revealed
by the third person. Neither the participant nor the operator
knew the group allocation, being both blinded to the protocol.
The participants from the in-office bleaching received a
prophylaxis of all teeth. The lips, cheeks and tongue were
isolated using the ArcFlex
lip retractor. The operators then
isolated the gingival tissue of the teeth to be bleached by using
a light-cured resin dam (Top Dam
). They applied a 35%
hydrogen peroxide gel (Whiteness HP
) for a total of 45
minutes. Every 15 minutes during the 45-minute session, they
refreshed the in-office bleaching agent. Participants repeated
the in-office bleaching treatment 1 week later.
For participants assigned to the at-home group, an alginate
impression of each subject’s maxillary arch was prepared and
filled with dental stone. To produce study models, block-out
material was not applied to the labial surfaces of teeth.
A 1-
mm soft vinyl material was used, provided by the manufacturer,
to fabricate the custom-fitted tray for the whitening gel. The
excess of labial and lingual surfaces was trimmed 1 mm from
the gingival junction. The tray and 16% carbamide peroxide gel
(Whiteness Standard
) was delivered to each subject with oral
instructions for use. All subjects were instructed to wear the
tray with agent for at least 6 hours at night. In the morning,
subjects were instructed to remove the tray, wash it and brush
their teeth with the fluoride toothpaste. The subjects were
instructed to wear the custom-fitted tray for 4 weeks. All
participants were instructed to brush their teeth regularly with
fluoridated toothpaste (Sorriso Fresh Gel
Shade evaluation - The subjective evaluation of color was per-
formed using a shade guide (Vita Lumina) in the same room
under artificial lighting. The shade guide’s 16 tabs were ar-
American Journal of Dentistry, Vol. 25, No. 4, August, 2012
ranged from highest (B1) to lowest (C4) value, making the color
C2 as number 7. Although this scale is not linear in the truest
sense, the changes were treated as representing a continuous and
approximately linear ranking for the purpose of analysis. The
measurement area of interest for shade matching was the middle
one third of the facial surface of the anterior central incisor.
Two calibrated evaluators, blinded to the allocation
assignment, recorded the shade of each participant’s teeth at
baseline and immediately after the first and second appoint-
ments for the in-office bleaching. For the at-home protocol, the
evaluators recorded the shade at baseline, and after 2 and 4
weeks of bleaching protocol. The two examiners were required
to have an agreement of at least 85% (Kappa statistic) before
beginning the study evaluation.
Tooth sensitivity evaluation - Participants were asked to record,
on a daily basis, their tooth sensitivity, according to the 5-point
Numerical Rating Scale,
with the following criteria: 0=
none, 1= mild, 2= moderate, 3= considerable and 4= severe.
These values were averaged for statistical purposes and
grouped into two categories: the overall percentage of subjects
with tooth sensitivity and the overall intensity of tooth
sensitivity. At the 2-year recall subjects were also asked to
record their tooth sensitivity.
All participants were evaluated at baseline, 1 week after the
end of the treatment and 2 years after bleaching. A standardized
questionnaire related to diet and oral hygiene behavior was
used specifically for the participants at the 2-year recall
appointment. Subjects were asked about the usage of whitening
toothpaste after bleaching; if they underwent another bleaching
treatment after the active treatment was completed; and the
daily intake frequency and type of staining beverage and food,
such as coffee, tea, wine, cola, artificial juices, chocolate,
beetroot or spinach, and smoking habits.
Statistical analysis - The analysis followed the intention-to-treat
protocol and involved all participants who were randomly
assigned, even those that were not able to be analyzed in the
scheduled recall visits.
In this case, we filled in the missing
data carrying the last observed value of such patient. The
statistician was blinded to the study groups. The agreement
between examiners was evaluated using the Kappa statistic.
Tooth shade changes were determined by calculating the
shift in the number of SGU that occurred toward the lighter
end of the scale. Two SGU were calculated: one taking the
baseline color vs. the color 1 week after the end of the
bleaching protocol (SGU 1 week) and the other taking the
baseline color vs. color taken at the 2-year recall (SGU 2
year). A paired Student t-test was used to compare the SGU 1
week and SGU 2 year for each bleaching therapy. A Student t
test for independent data was used to compare the bleaching
efficacy (SGU) at each assessment point for both therapies.
The least square mean differences as well as the confidence
interval were calculated.
The relative risks of tooth sensitivity for both bleaching
therapies were compared using the Fisher’s exact test ( =
0.05). The median of the tooth sensitivity intensity experienced
by each patient throughout the 4-week at-home and the 2-week
in-office therapies was used for statistical purposes. The
intensity of tooth sensitivity of both bleaching therapies were
compared using the Mann-Whitney test ( = 0.05).
American Journal of Dentistry, Vol. 25, No. 4, August, 2012
Fig. 1. Flow diagram of the clinical trial including detailed information on the
excluded participants.
Table 1. Change in tooth shade (mean and standard deviation) between
assessment points for the two treatment groups (*).
SGU SGU Least square
(Baseline (Baseline mean difference
vs 1 wk) vs 2 yrs) P value* (95% CI)
At-home (n=30) 6.27 ± 1.5 6.02 ± 1.4 0.77 0.25 (-0.5 – 1.0)
In-office (n=30) 5.62 ± 0.9 5.32 ± 0.7 0.87 0.30 (-0.1 – 0.7)
P-value** 0.51 0.47
* Paired t-test; ** unpaired t-test; CI: Confidence interval.
Figure 1 depicts the participant flow diagram. All 60
participants who began the study, completed it. The mean ages
of the participants were 21 ± 3.8 and 21 ± 3.2 years for at-home
and in-office groups respectively. Males comprised 47.8 and
26.6% of participants in the at-home and in-office groups,
Table 1 depicts the SGU calculated after each assessment
point for both bleaching protocols. Both techniques yielded a
whitening of approximately five to six shade guide units. No
significant darkening occurred by the 2-year recall (P< 0.77 and
P< 0.87 respectively, for at-home and in-office techniques).
The bleaching efficacy of at-home and in-office bleaching was
not statistically significant either 1 week after the end of
treatment (P< 0.51) or 2 years later (P< 0.47).
Table 2 shows the number of subjects who reported tooth
sensitivity during bleaching treatment. Statistically similar (P =
0.12) absolute risk of tooth sensitivity was reported by subjects
Clinical efficacy of tooth bleaching 201
Fig. 2. Levels of sensitivity (%) perceived by the participants for both groups
immediately after the bleaching protocol. No severe sensitivity was observed
in this study.
Table 2. Comparison of the number of subjects who experienced tooth sensitivity
during the bleaching regimen as well as absolute and relative risk (*).
Tooth sensitivity
during treatment
Absolute risk Relative risk
Yes No P value* (95% CI) (95% CI)
At-home 20 10 66.7 (48.8 – 80.7)
0.12 1.3 (0.97 – 1.7)
In-office 26 4 86.7 (70.3 – 94.7)
* Fisher’s exact test; CI: Confidence interval.
Table 3. Medians and interquartile range of the scores of tooth sensitivity
intensity for each bleaching technique.
Tooth sensitivity
Groups Median (1
interquartile) P value*
At-home 1(0/2) 0.043
In-office 2 (1/3)
* Mann Whitney test.
from the in-office and at-home bleaching. None of the
participants from either bleaching technique complained of
tooth sensitivity at 2 years (P = 1.0).
Regarding tooth sensitivity intensity (Table 3), there was a
statistical difference between the bleaching therapies (P =
0.001). Most of the participants from the at-home group
experienced none to mild sensitivity, while most in the in-office
bleaching group experienced mild to moderate sensitivity.
Figure 2 shows the levels of sensitivity (%) perceived by the
participants for both groups during the treatment. At 2 years,
none of the participants reported tooth sensitivity.
Ten subjects (33.3%) from the in-office group and 18
subjects (60%) from the at-home group consumed at least one
kind of staining beverage every day. Only one subject from the
in-office group and three subjects from the at-home group were
daily smokers. From the in-office group, one subject reported
using a new bleaching agent after treatment and none of them
202 Tay et al
Table 4. Behavior of participants throughout the 2 years after the end of the
bleaching therapy.
2-year evaluation
Parameter At-home In-office
Daily staining beverage consumption
Yes 18 (60%) 10 (33.3%)
No 12 (40%) 20 (66.7%)
Daily frequency of staining beverage intake
None 12 (40%) 20 (66.7%)
Once a day 5 (16.7%) 9 (30%)
Two or three times a day 13 (43.3%) 1 (3.3%)
Four or more times a day 0 (0%) 0 (0%)
Daily smoker
Yes 3 (10%) 1 (3.3%)
No 27 (90%) 29 (96.7%)
Tooth bleaching repeated
Yes 0 1 (3.3%)
No 30 (100%) 29 (96.7%)
Use of whitening toothpastes
Yes 4 (13.3%) 0
No 26 (86.7%) 30 (100%)
used tooth whitening paste, while in the at-home group none of
the subjects reported using a new bleaching agent, and four
(13.3%) subjects used a whitening toothpaste. Details of the
daily frequency of staining beverage and subject behavior are
shown in Table 4.
Investigators have used different methodological
approaches to assess tooth shade and changes in tooth shade
resulting from bleaching treatments.
Recently, digital systems
(spectrophotometers, colorimeters or digital cameras) have
been used to measure tooth shades. These systems express
color in three-dimensional specifications and allow for more
accurate assessments. These digital systems are precise
instruments that produce highly reliable, easily evaluated
results. High cost and complex operation could be unique
disadvantages for some of these methods.
A recent study
evaluating the validity and reliability of
visual assessment of tooth color using a commercial shade
guide (Vitapan Classical shade guide) reported that despite its
subjectivity such visual assessment was a valid method, with
good reliability in differentiating between dark and light colors.
Other clinical studies
comparing the color change after
different bleaching techniques using a subjective method (shade
guide) and an objective method (spectrophotometer) usually
reported similar outcomes with both evaluation methods. In the
present study, the shade guide was used for color change
evaluation because it is an easy, fast and reliable method
supported by the literature.
The results of the present investigation showed that both
techniques were effective and reached similar results when
used following their respective protocols. At the end of the
treatment, a mean variation of 6.2 and 5.6 SGUs were observed
for the in-office and at-home techniques, respectively. Auschill
et al
showed that at-home bleaching with 10% carbamide
peroxide gel and in-office bleaching with 35% hydrogen
peroxide lightened teeth six shades on the Vita color scale,
which is in line with the present investigation and other
American Journal of Dentistry, Vol. 25, No. 4, August, 2012
The efficacy of a bleaching technique depends on the
concentration of the hydrogen peroxide and the application
However, the relationship between hydrogen
peroxide concentration and application time is not linear but
This explains why for the 16% carbamide
peroxide ( 5% hydrogen peroxide) a 4-week treatment with at
least a 6-hour daily use ( a total of 168 hours) was required to
reach the same whitening effect produced by an overall 1½-
hour treatment time using of the 35% hydrogen peroxide gel.
This exponential relation was recently demonstrated in a
laboratory setting and means that bleaching gels with a higher
peroxide concentration needed fewer applications/reduced time
to produce a similar bleaching effect.
To the extent of the authors’ knowledge, no study has
evaluated the longevity of whitening produced by bleaching
with 35% hydrogen peroxide for prolonged periods, i.e. more
than 1 year. Previous findings
have already reported color
rebound for at-home bleaching. Ritter et al
reported that 38
months after the end of at-home bleaching treatment, 62% of
the participants reported slight darkening. Leonard et al
a color rebound of two shade guide units over a period of time
ranging from 6 to 47 months with 10% carbamide peroxide,
which was similar to the findings of other clinical trials.
It is
widely reported that with in-office bleaching the color reverses
in a few days.
This E reversal was shown to be of the
order of 51% and 65% after 1 and 6 weeks post-bleaching,
respectively for eight in-office products.
Many aspects may account for this long-term color reversal.
The effect of staining produced by beverages and food is
usually believed as explanation for the slight darkening that
follows bleaching over time.
However one should consider
that this staining is usually extrinsic and although it may affect
the overall perception of whiter teeth, this can be easily
removed by professional cleaning. In the present investigation
none of the consumption parameters were shown to be
associated with the longevity of the treatment. These findings
do not necessarily mean that these parameters do not influence
the longevity of the whitening, since the study design was not
planned to detect such association. Further studies should
address this question.
Color rebound can also result from reversal of oxidative
reactions so that the shorter and lighter molecules produced by
the bleaching therapy return to their original configuration and
yellower color. Another explanation for the color rebound is the
fact that as teeth get older, there is a continuous deposition of
secondary dentin by the pulp.
As the dentin thickness
increases, teeth appear yellower. Unfortunately, the length of
time that it takes to change one Vita shade tab due to deposition
of secondary dentin is unknown and may take longer than the
period of 2 years of the current study. Future studies need to be
done to test this hypothesis.
Surprisingly, however, the present investigation reported
that both techniques achieved stable results at the 2-year recall.
A 2-year follow-up may be a short recall time to detect the
effects of continuous deposition of secondary dentin on the
outcome of bleaching.
Another interesting finding of the present investigation was
that this study challenged the widespread concept that the at-
home bleaching may produce more long-lasting results than in-
American Journal of Dentistry, Vol. 25, No. 4, August, 2012
office bleaching, which is in agreement with a 9-month follow-
up study.
The result observed immediately after in-office
bleaching is the sum of the oxidative processes, tooth
dehydration and demineralization. When the immediate
bleaching result is compared to the color measured some weeks
later, an unrealistic color reversal is usually reported,
but this
does not mean ineffective bleaching, since it is due to
and rehydration that occurs after each
bleaching session. It is known that isolation can cause the teeth
to dehydrate, and it takes at least 30 minutes for teeth to
Also, most of the bleaching gels possess an acidic
pH ranging from 2.4 to 6.2 and therefore teeth are also
demineralized by the bleaching gels.
In order to gather more stable results with less color
reversal, more than one clinical session may be required and
this seems to be the key feature for the long-lasting results of
the present study. According to Shethri et al
only after a
second session of in-office bleaching treatment, tooth lightness
improved significantly. Therefore, a single in-office treatment
with 35% hydrogen peroxide seems to be not enough to bleach
teeth to the same rate of the well-accepted at-home technique.
Tooth sensitivity is the most common adverse side effect of
bleaching and according to Leonard et al
25-75% of subjects
receiving the active bleaching ingredient experience tooth
sensitivity. In the present study it was observed that the
incidence of tooth sensitivity in the at-home and in-office
bleaching was similar, which is in agreement with others.
However, significant differences were observed between
techniques when the intensity of tooth sensitivity was compared
as well as in a previous study.
While most of the participants
from the at-home bleaching experienced none to mild
sensitivity, most of the participants from in-office group
reported mild to moderate sensitivity.
Cooper et al
showed that a very fast passage of hydrogen
peroxide occurs through the dental structure; within 15 minutes
after application, hydrogen peroxide can be detected at the
pulp. Thus, using a higher hydrogen peroxide concentration,
there may be larger amounts of reactive species arriving to the
pulp, leading to a more intense inflammatory response and
tooth sensitivity. A previous laboratory study
that the cytotoxicity of carbamide peroxide bleaching gels was
dose-dependent, with the highest concentration causing the
most intense cytopathic effects to the cultured cells.
None of the participants from both bleaching techniques
reported tooth sensitivity in the 2-year recall. Generally, tooth
sensitivity caused by at-home bleaching occurs in the first 2
weeks of treatment,
often in the first few days and decreases
as the teeth are accustomed to the procedure, but occasional
single-day episodes of sensitivity may occur over the course
of the treatment.
For in-office bleaching, tooth sensitivity
usually occurs within the 24 hours following the bleaching
The lack of tooth sensitivity after long-term
evaluation seems to be consistent in the literature. Most of the
studies that evaluated the longevity of tooth bleaching
reported that subjects did not report tooth sensitivity after the
end of the bleaching.
In the present study tooth sensitivity was assessed using a 5-
point numerical rating scale (NRS) as this has been used for
tooth sensitivity evaluation in the great majority of the clinical
Clinical efficacy of tooth bleaching 203
trials involving bleaching and therefore allows comparison with
the earlier results.
The other common scale for
tooth sensitivity evaluation is the visual analog scale
Although we have not found in the bleaching
literature any study that compared the VAS and 5-point NRS,
some earlier studies pointed out that both scales yield similar
This lack of comparison between these two scales
should be the focus of future investigations regarding tooth
sensitivity from bleaching therapies.
It is worth mentioning the limitations of the present study.
The fact that the participants were taken from a convenient
sample (participants seeking professional dental treatment) may
lead to bias, since they are much more motivated than
participants taken from outside the school. In addition, most of
the participants were young adults, which affect the
generalizability of the findings of the present investigation to
the overall population.
In summary, both techniques were effective to whiten teeth
and produced long-lasting and satisfactory results. Thus, the
choice of the bleaching technique depends on the professional
as well as patient preferences. At-home and in-office bleaching
are effective protocols for vital teeth bleaching, however a
higher intensity of tooth sensitivity was reported for in-office
a. Vita Zahnfabrik, Bad Säckingen, Germany.
b. FGM Dental Products, Joinville, SC, Brazil.
c. Colgate-Palmolive Company, São Paulo, SP, Brazil.
Disclosure statement: The authors declared no conflict of interest.
Dr. Tay and Dr. Kose are graduate students, and Dr. Reis and Dr. Loguercio are
Adjunct Professors, Department of Restorative Dentistry. School of Dentistry.
State University of Ponta Grossa, Paraná, Brazil; Dr. Herrera is a graduate
student, Department of Restorative Dentistry, Endodontics. School of Dentistry
of Piracicaba. State University of Campinas, Campinas, São Paulo, Brazil.
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... 8,9 In-office bleaching treatment employs a high concentration of HP with applications lasting from 15 to 60 minutes and usually requires more than one visit. 10,11 A previous systematic review 7 and randomized controlled clinical trial (RCT) 12 has demonstrated that at-home and in-office bleaching produced similar efficacy in color changes. However, in-office bleaching is considered a faster option with greater color reversal compared with athome bleaching. ...
... 15 The risk of TS caused by in-office bleaching is between 16.7% and 100%, while it ranges from 37% to 90% for at-home bleaching. 7 Moreover, the intensity of TS caused by in-office bleaching is higher than that in at-home bleaching, 12,16 which may be related to the association with the higher concentration of bleaching gel used. 17 The combination of at-home and in-office bleaching has been suggested to achieve better clinical results, 18,19 including faster whitening effects, 18,20 less TS, 21 and better color stability. ...
... The excess labial and lingual surfaces were cut 1 mm from the gingival junction. 12 Participants were instructed to dispense 10% CP over the buccal surface for the anterior teeth and to remove the excess after positioning them. 20 The bleaching gel was applied via the tray for eight hours overnight for a period of seven days, which was regarded as a session of at-home bleaching treatment. ...
Objective: The aim of this study was to compare the clinical efficacy of at-home, in-office, and combined bleaching regimens. Methods: Forty-eight participants were recruited and randomly divided into four groups based on the bleaching regimen (n=12) as follows: 1) at-home bleaching using 10% carbamide peroxide (Opalescence PF 10%, Ultradent) for 14 days (HB); 2) two sessions of in-office bleaching using 40% hydrogen peroxide (Opalescence BOOST PF 40%, Ultradent) with a one-week interval (OB); 3) one session of in-office bleaching followed by at-home bleaching for seven days (OHB); and 4) at-home bleaching for seven days followed by one session of in-office bleaching (HOB). Tooth color was measured using a spectrophotometer (Easyshade, Vita ZahnFabrik) at baseline (T0), day 8 (T1), day 15 (T2), and day 43 (T3, four weeks after the end of the bleaching treatment). The color data were calculated using the CIEDE2000 (ΔE00) and whiteness index for dentistry (WID) formulas. Tooth sensitivity (TS) was recorded using a visual analogue scale (VAS) for 16 days. Data were analyzed by one-way analysis of variance (ANOVA) and the Wilcoxon signed-rank test (α=0.05). Results: All bleaching regimens resulted in a significant increase in WID values (all p<0.05), while no significant differences in WID and ΔWID values were found among the different groups at each time point (all p>0.05). Significant differences in ΔE00 values were observed between T1 and T3 for all groups (all p<0.05), while no significant differences in ΔE00 values were found among the different groups at any time point (all p>0.05). Significantly lower TS values were observed in the HB group than in the OB and HOB groups (p=0.006 and p=0.001, respectively). Conclusions: All bleaching regimens resulted in great color improvement, and different regimens led to similar color changes at any of the evaluation time points. The sequence of treatments applying in-office bleaching or at-home bleaching did not affect the bleaching efficacy. The in-office bleaching and combined bleaching regimens yielded a higher intensity of TS than did at-home bleaching.
... Cadenaro et al, in 2006 through his research proved that in-office bleaching had no significant effect on tooth surface roughness, this supports the results of research by Abu-saq Al Yami A, et al (2019). 16 Research that aims to compare tooth sensitivity in athome bleaching and in-office bleaching techniques has been carried out by several researchers, namely Basting RT (2012), Tay LY, et al (2012), Moghadam, et al (2013), and Mounika A, et al (2018) as in Table 3. Basting RT, et al (2012) conducted a study which proved that the prevalence and intensity level of tooth sensitivity in the at-home bleaching technique with 20% carbamide peroxide was higher than inoffice bleaching technique with hydrogen peroxide 35% and 38%. The prevalence of tooth sensitivity in these two techniques was 35 out of 81 total subjects. ...
... 20 The research by Mounika A, et al (2018), a study regarding the comparison between the in-office bleaching and at-home bleaching techniques discussed earlier, also aims to compare the tooth sensitivity that occurs in the two techniques. The results of this study support the results of research from Tay LY, et al (2012). This study proves that the intensity level of tooth sensitivity felt by subjects in in-office bleaching with 35% hydrogen peroxide is significantly higher than at-home bleaching with 16% carbamide peroxide. ...
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Bleaching has become the treatment of choice for most tooth discolorations. In-office bleaching and at-home bleaching are the most frequently performed vital tooth bleaching techniques. Both of these techniques are proven to improve tooth discoloration, but unwanted effects can also occur, such as tooth sensitivity and increased tooth enamel surface roughness. Tooth sensitivity is a common side effect of bleaching procedures and the effect of bleaching on dental hard tissue is still a matter of controversy. This literature aims to conduct an integrative literature study with scientific evidence related to the potential results, enamel surface roughness, and tooth sensitivity in in-office bleaching and at-home bleaching techniques. Method: Analyzing journals from databases such as Medline (PubMed), Ebsco, Google Scholar, textbooks, and accredited national journals. Conclusion: This review reveals that at-home bleaching has the same potential as in-office bleaching in lightening tooth color. Higher tooth sensitivity was found in in-office bleaching, however in at-home bleaching with 20% carbamide peroxide the tooth sensitivity could be higher. An increase in tooth enamel surface roughness can occur in both techniques, but the at-home bleaching technique is more influential
... Considering TS as a condition caused by the action of DB, the analysis of the studies, addressing the type of DB used, found that all of them had used in-office DB [3,8,12,[19][20][21] and worked with the same product concentration (35% H2O2) [3,12,[19][20][21] with the exception of two studies, one that used 40% H2O2 [8] and another that, in addition to 35% H2O2, used H2O2 in combination with titanium dioxide with 6% nitrogen (6% H2O2 / TiO2 with N) [20]. Even though the literature reports that the available bleaching techniques and agents are effective and have demonstrated similar behaviours [23], in-office DB generates greater intensity of TS [23][24][25]. ...
... It is also considered to be one of the most conservative and cost-effective dental treatments to improve a person's smile [27]. This way, the literature has reported DB effectiveness in some clinical trials [23][24][25]28]. ...
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Objectives Perform a systematic review to evaluate the influence of smoking on the effectiveness of tooth whitening (TW) and to analyze whether tooth sensitivity is different between smokers and non-smokers.Materials and methodsA systematic review modeled according to the PRISMA guidelines was conducted. PubMed, Embase, Web of Science, Cochrane, Scopus, and OpenGrey databases were searched for related clinical trials. The population, exposure, comparison, outcomes (PECO) was individuals who had TW performed, smoking individuals, non-smoking individuals, and effectiveness of TW, respectively. Risk of bias was assessed with the ROBINS-I tool, and data from included studies were extracted by two researchers independently. The certainty of the evidence was evaluated using the GRADE (Grading of Recommendations, Assessment, Development, and Evaluations) approach.ResultsFive studies were selected for qualitative analysis. The ROBINS-I tool classified 3 studies as having a moderate risk of bias, one study as having a serious risk of bias, and one with a critical risk. GRADE performed only for color change results and showed a low certainty of evidence. Limited evidence suggests that effectiveness of TW between smokers and non-smokers is similar. The tooth sensitivity also does not seem to be influenced by smoking. Due to the heterogeneity of the data, a meta-analysis could not be performed.Conclusions Effectiveness of TW between smokers and non-smokers is comparable. The tooth sensitivity also does not seem to be influenced by smoking.Clinical relevanceThe effectiveness of bleaching among smokers and non-smokers appears to be similar. Tooth sensitivity during TW also appears not to be influenced by smoking.
... In-office bleaching is a fantastic option for people who are unable to use at-home bleaching or want to achieve satisfactory results immediately [2]. In-office therapy, on the other hand, has been shown to produce higher postoperative tooth sensitivity [3][4][5]. ...
... Few studies have examined fluoride's ability to remineralize enamel after a bleaching procedure (either topically or in the bleaching gel's composition) under the parameters outlined above. Both topical and fluoride bleaching gels were tested in this study [5,6,19]. ...
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Background This study aimed to evaluate the micro-shear bond strength (mSBS) of an adhesive applied to bleached enamel to determine the effects of fluoride supply and restoration time on the mSBS. Methodology In this study, we bleached 130 samples of enamel and split them into the following three groups of 40 each: group MI: McInnes bleaching solution; group MIF: McInnes bleaching solution + topical acidulated phosphate fluoride gel; group FMI: 2% fluoridated McInnes bleaching solution. Non-bleaching or fluoridation was performed on a group of 10. Subgroups were created for each group (except for the control) to be restored for seven, 14, or 21 days. The mSBS test was performed on a universal testing machine after Tygon tubes were filled with composite resin and put on enamel surfaces. Tukey’s post-hoc test (p = 0.05) and two-way analysis of variance were employed to analyze the data. Results The mSBS values obtained for all groups immediately and after seven days were lower, while at 14 and 21 days were similar to the control group. According to the data, group FMI had greater mSBS levels than groups MI and MIF, both immediately and seven days later. Conclusions When in-office bleaching was employed, only the fluoride McInnes solution was successful in quickly correcting the adverse effects of low mSBS.
... Considering TS as a condition caused by the action of DB, the analysis of the studies, addressing the type of DB used, found that all of them had used in-office DB [3,8,12,[19][20][21] and worked with the same product concentration (35% H2O2) [3,12,[19][20][21] with the exception of two studies, one that used 40% H2O2 [8] and another that, in addition to 35% H2O2, used H2O2 in combination with titanium dioxide with 6% nitrogen (6% H2O2 / TiO2 with N) [20]. Even though the literature reports that the available bleaching techniques and agents are effective and have demonstrated similar behaviours [23], in-office DB generates greater intensity of TS [23][24][25]. ...
... It is also considered to be one of the most conservative and cost-effective dental treatments to improve a person's smile [27]. This way, the literature has reported DB effectiveness in some clinical trials [23][24][25]28]. ...
Full-text available
The authors aimed to conduct a systematic review to assess data from the current literature on the effectiveness of low-level laser therapy (LLLT) in preventing tooth sensitivity (TS) after tooth whitening (DB). PRISMA guidelines for systematic reviews were followed. Clinical trials evaluating the treatment of LLLT in patients with sensitivity after tooth whitening were selected. A full bibliographic search was performed on May 4, 2021, in the following databases: Embase, MEDLINE via PubMed, SciELO, VHL Regional Portal, Web of Science, Gray Literature, Scopus, and Cochrane Library. This study followed Cochrane’s recommendations for analyzing risk of bias. A total of 1054 studies were found (255 studies were excluded because they were duplicates and 785 because of titles and abstracts). Only 14 articles were selected for analysis, of which eight were excluded because they had one or more exclusion criteria, resulting in six articles included in this systematic review, the vast majority being classified as low risk of bias. The studies reviewed indicated that LLLT showed promise in preventing TS after TB. However, evidence is limited and more clinical trials with low risk of bias are needed to reach a definitive conclusion on the action of LLLT in pain control after TB.
... On the other hand, as higher HP concentrations are applied, higher tooth sensitivity (TS) levels also occur with in-office bleaching compared with at-home bleaching. [6][7][8] This is because TS after bleaching procedures is due to the ability of HP to penetrate the dental structure and reach the pulp chamber during bleaching, promoting an inflammatory response of the pulp. 9 Various strategies have been tested to reduce the intensity or risk of TS, such as the application of of gel used were also evaluated. ...
Purpose: The objective of this study was to evaluate if the application method (tip with brush or tip without brush) and hydrogen peroxide (HP) concentration (6% or 35% self-mixing) of in-office bleaching gel influences the penetration of HP into the pulp chamber, color change, and the amount of bleaching gel used. Methods: Forty healthy premolars were randomly divided into the following five groups (n=8): no treatment; HP6% using a tip with a brush, HP6% using a tip without a brush, HP35% using a tip with a brush, and HP35% using a tip without a brush. After treatments, the HP concentration (μg/mL) within the pulp chamber was determined using UV-Vis spectrophotometry. The color change (ΔEab, ΔE00, and ΔWID) was evaluated using a digital spectrophotometer. The amount of gel used (g) in each group was measured using a precision analytical balance. Data from each test were submitted to parametric tests (α=0.05). Results: The tip with a brush resulted in a lower amount of HP inside the pulp chamber and less gel used when compared with the tip without a brush, regardless of HP concentration (p<0.05). However, regarding the tip used, although no significant difference was observed when HP35% was used (p>0.05), a higher whitening effect was observed when the 6% HP was applied without a brush as opposed to with a tip brush (p<0.05). Conclusions: The use of a tip with a brush, regardless of the in-office bleaching gel concentration (6% or 35% self-mixing), presented a lower penetration and lower volume of spent gel when compared to a tip without brush. However, the whitening effect depends on the concentration of HP used.
... 25 Klinikte geçirilen süreyi kısaltması, hassasiyetin daha az olması ve en az ofis tipi kadar başarı sağlaması, birçok hekimi ev tipi beyazlatma uygulamalarına yöneltmiştir. 26 Renk çalışmalarında, görsel olarak algılanabilir ve kabul edilebilir eşik değerleri bilmek ve dikkate almak klinik diş hekimliği için oldukça önemlidir. Renk farklılıklarının değerlendirilmesinde kullanılan CIEDE2000 formülünün, kliniğe daha iyi uyum sağladığı gösterilmiştir. ...
... Among the dentist-supervised techniques, dental bleaching can be performed in-office or at home. 5 In-office bleaching carries the advantage of having better professional control of the product application and faster results but with the onus of presenting higher risk and intensity of tooth sensitivity. [6][7][8] At-home dental bleaching uses low concentrations of bleaching gels in customized bleaching trays with the advantage of reduced chair time and lower cost. 9,10 Although it takes 2 to 3 weeks to bleach teeth, athome bleaching produces low risk and intensity of tooth sensitivity, 6,7 and it was reported to be preferred by many patients. ...
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Objective: Few studies evaluated low concentrations of hydrogen peroxide protocols. The aim of this paper was evaluated two application protocols using 4% hydrogen peroxide in at-home bleaching. Materials and methods: Eighty-six patients with upper canines' shade A2 or darker were randomly allocated under two experimental conditions: two daily applications of 1 h each or a 2-h single application. Color change was evaluated using Vita Classical, Vita Bleachedguide, and digital spectrophotometer weekly and 1 month after the bleaching procedure through one-way ANOVA. The risk and intensity of tooth sensitivity (TS) was assessed through visual and numeric rating scale and measured by Fisher's exact test, Mann-Whitney test and one-way ANOVA respectively. Results: After 3 weeks, the mean difference for the ΔSGU Vita Classical (1.0; 95% CI -0.1 to 2.0), ΔEab (0.7; 95% CI -1.4 to 2.8), ΔE00 (0.1; 95% CI -1.4 to 1.6) and Wi (1.8; 95% CI -1.9 to 5.5) presented no difference (p > 0.08). The relative risk for TS was 0.91 (0.72 to 1.14) without significant difference neither in the risk (p = 0.6) nor in the TS intensity for both pain scales (p > 0.65). Conclusions: The application protocols evaluated (two daily applications of 1 h each or a 2-h single application) for at-home bleaching with 4% hydrogen peroxide did not showed differences in color change and tooth sensitivity. Clinical relevance: Higher amount of active hydrogen peroxide in two daily applications for at-home bleaching neither accelerate bleaching nor increase the risk or intensity of tooth sensibility.
... Such adverse effect has been related to the intense trans-amelodentinal diffusion of unreacted (H 2 O 2 -free) hydrogen peroxide (H 2 O 2 ) that causes irreversible damage to pulp cells [5][6][7][8]. This occurs because of the high concentration of this low-oxidation-potential reactive molecule in bleaching gels, which main objective is to break the double links of colored pigments (chromophores), favoring the chromatic change of dental tissues [9][10][11][12]. ...
Objective: To assess the influence of coating the enamel with a nanofiber scaffold (NS) and a polymeric catalyst primer (PCP) on the esthetic efficacy, degradation kinetics of hydrogen peroxide (H2O2), and trans-amelodentinal cytotoxicity of bleaching gels subjected or not to violet-LED irradiation. Methodology: The following groups were established (n=8): G1- No treatment (negative control); G2- NS+PCP; G3- LED; G4- NS+PCP+LED; G5- 35% H2O2 (positive control); G6- NS+PCP+35% H2O2+LED; G7- 20% H2O2; G8- NS+PCP+20% H2O2+LED; G9- 10% H2O2; G10- NS+PCP+10% H2O2+LED. For esthetic efficacy analysis, enamel/dentin discs were stained and exposed for 45 minutes to the bleaching protocols. To assess the cytotoxicity, the stained enamel/dentin discs were adapted to artificial pulp chambers, and the extracts (culture medium + components diffused through the discs) were collected and applied to MDPC-23 cells, which had their viability, oxidative stress, and morphology (SEM) evaluated. The amount of H2O2 diffused and hydroxyl radical (OH•) production were also determined (two-way ANOVA/Tukey/paired Student t-test; p<0.05). Results: G6 had the highest esthetic efficacy compared to the other groups (p<0.05). Besides the esthetic efficacy similar to conventional in-office bleaching (G5; p>0.05), G10 also showed the lowest toxic effect and oxidative stress to MDPC-23 cells compared to all bleached groups (p<0.05). Conclusion: Coating the enamel with a nanofiber scaffold and a polymeric catalyst primer, followed by the application of 10%, 20%, or 35% H2O2 bleaching gels irradiated with a violet LED, stimulates H2O2 degradation, increasing esthetic efficacy and reducing the trans-amelodentinal toxicity of the treatment.
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Objectives The use of calibrated, commercial digital cameras for dental applications is promising. The color accuracy of various calibration models were evaluated as applied to three commercial digital cameras for use in dental color matching. Methods CIE LAB values of 264 color patches and 65 shade tabs were measured with a spectroradiometer. Digital images of the samples were taken with the Nikon D100, Canon D60 and Sigma SD9 cameras. Four regression models were formulated from the color patch CIE LAB and the digital image values. Shade tab CIE LAB colors were predicted by applying the digital image values into the calibration models and were compared to the measured CIE LAB values. The Wilcoxon Rank-Sum test determined if the 12 camera/calibration models differed significantly from the color measurement setup. Results Every camera/calibration model (ΔE's ranging from 1.79 to 5.25) showed a statistically significant difference from the color measurement setup. Significance Commercial SLR digital cameras when combined with the appropriate calibration protocols showed potential for use in the color replication process of clinical dentistry.—Reprinted with permission of Elsevier Publishing.
This clinical study compared the efficacy of three different bleaching techniques with respect to the bleaching times required in order to achieve six grades of whitening in human teeth. Any side effects that were noted and the patients' acceptance of the method were recorded by a visual analog scale ranging from 0 to 10. Moreover, epoxy casts from the study teeth were analyzed by scanning electron microscopy in order to detect any potential changes in the enamel surface due to treatments. Thirty-nine volunteers participated in the study and were allocated randomly to one of three different bleaching treatments: Group A (n=13) used Whitestrips (over-the-counter technique; one cycle=30 minutes), Group B (n=13) used Opalescence PF 10% (at-home bleaching technique; one cycle=8 hours) and Group C (n=13) used Opalescence Xtra Boost (in-office bleaching technique; one cycle=15 minutes) until a defined whitening of six tabs compared to the baseline were reached (assessed by the VITA shade guide). All three methods achieved six grades of whitening. The mean treatment time required to reach the defined level of whitening was 31.85 +/- 6.63 cycles in Group A, 7.15 +/- 1.86 cycles in Group B and 3.15 +/- 0.55 cycles in Group C. All products differed significantly from each other in terms of treatment cycles and required treatment time (p < 0.001 by ANOVA and Mann-Whitney-U-test). Using the VA scale, side effects noted within the three groups were minimal. Tooth hypersensitivity ranged from 2.62 (Whitestrips) to 3.38 (Opalescence PF), and gingival irritation ranged between 0.23 (Opalescence Xtra Boost) and 0.85 (Whitestrips). The most accepted method was the at-home bleaching technique. None of the teeth studied showed detectable enamel surface changes in the subsequent SEM analysis using 200x and 2000x magnification.
Purpose: The purposes of this retrospective case series study were to evaluate safety issues and determine participants' perceptions of a nightguard vital bleaching (NGVB) technique approximately 10 years post-treatment (average, 118 mo; range, 108–144 mo). Materials and Methods: The study sample included 30 (79%) of 38 participants who had completed a previous NGVB study using a 10% carbamide peroxide solution (Proxigel® or Gly-Oxide®) in a custom tray for 6 weeks. Participants were asked whether there had been any change in the shade of their teeth post-treatment and, if so, to quantify the change on a verbal scale. In addition, 19 participants had gingival index and tooth vitality evaluated clinically, external cervical root anatomy evaluated radiographically, and enamel surface changes evaluated microscopically. Results: Thirty-five (92%) of the original 38 participants had successful lightening of their teeth. At approximately 10 years post-treatment (average, 118 mo; range, 108–144 mo), external cervical resorption was not diagnosed and gingival index and tooth vitality findings were considered within the normal expectations for the sample studied, suggesting minimal clinical post-NGVB side effects at approximately 10 years. Scanning electron microscopic observations did not reveal substantial differences between treated and nontreated surfaces. Color stability, as perceived by 43% of the participants, may last approximately 10 years (average, 118 mo; range, 108–144 mo) post-treatment.
Background: The scientific literature is lacking in long-term clinical data on the duration of efficacy and post-treatment side effects of nightguard vital bleaching. Purpose: This longitudinal clinical study was undertaken (1) to determine the clinical efficacy and duration of efficacy at 3, 6, and 47 months post treatment of a peroxide-containing whitening solution; (2) to evaluate safety issues with respect to using a peroxide whitening solution; and (3) to determine patients' perceptions of the whitening technique. Materials and methods: This project was part of a nightguard vital bleaching study involving human participants. The study teeth for efficacy and duration of efficacy when using a 10% carbamide peroxide solution were the four maxillary central and lateral incisors, with the tooth shade being taken from the middle third of the tooth. Safety issues evaluated were the changes in gingival index (GI), plaque index (PI), nonmarginal gingival index (NMGI), nongingival oral mucosal index (NGOMI), and tooth vitality (TV). Radiographic changes of the study teeth and the patients' perceptions of tooth sensitivity (TS) or gingival irritation (Girr) during treatment and post treatment were also evaluated. Results: The active 10% carbamide peroxide whitening solution used in this study was effective in lightening teeth (98%), and this effect was sustained at a mean of 47 months post treatment in 82% of the participants. When evaluating safety issues, 66% of the participants using the active solution reported TS or Girr. No one reported TS or Girr or any other adverse effects at the end of the study. Conclusions: The results of this study concur with those of previously reported studies that nightguard vital bleaching using a 10% carbamide peroxide whitening solution according to the manufacturer's instructions is efficacious and safe, with minimal side effects. In addition, long-term shade retention was reported by 82% of the participants at the end of the study, with no adverse side effects. Clinical significance: Results of this study should reassure dentists that nightguard vital bleaching is a safe, effective, and predictable method to lighten teeth. The whitening effect lasted up to 47 months in 82% of the patients, with no adverse side effects reported at the end of the study.
Purpose: The purpose of this study was to evaluate the 2-year effectiveness of a carbamide peroxide at-home bleaching gel used to provide tooth lightening treatment. Material and Methods: Twenty-nine patients participated in the original study, during which they treated their maxillary teeth with a 10% carbamide peroxide gel nightly for 2 weeks. Shades were determined before and after treatment by comparison with a Vita shade guide. Twenty-four patients (a recall rate of 83%) were recalled for evaluation 2 years after the initial bleaching treatment. The shade of the maxillary incisors was evaluated and compared with shades before, immediately after, and at 6 months and 2 years after initial treatment. Data were analyzed using a repeated-measures analysis of variance. Results: At 2 years after bleaching with a 10% carbamide peroxide gel, the median shade was D2, a six-increment difference from the baseline median of D3. Twenty of 24 patients (83.3%) had a shade change of two or more units, which is the threshold value for bleaching efficacy using American Dental Association guidelines. The lightening result remained statistically significant (p <.0001) at 2 years.
To evaluate whether the use of a desensitizing agent before at-home vital bleaching decreased this sensitivity. After informed consent, 60 subjects, 18-31 years of age, participated in the study and were divided into desensitizer and placebo groups. Before bleaching treatment with 16% carbamide peroxide (CP), a placebo or desensitizer gel (DG; 5% potassium nitrate and 2% sodium fluoride) was applied in the tray and used by patients for 10 minutes. Color was evaluated at the baseline, second and fourth week following the initial delivery of bleaching trays. Color change was measured using the Vita Classic Shade Guide arranged by value. The subjects recorded their perception of tooth sensitivity on a 0-4 scale. The bleaching treatment at each week recall was evaluated by repeated measures ANOVA. The percentage of patients with tooth sensitivity was evaluated by Chi-square test. The tooth intensity ratio (% of days with tooth sensitivity) as well as the tooth sensitivity intensity between groups were analyzed using chi-square and the Mann-Whitney tests, respectively (alpha = 0.05). The use of DG did not affect the bleaching efficacy of the CP (P > 0.05). The prevalence and intensity of tooth sensitivity was similar for both groups (P > 0.05). However, participants from the placebo group had sensitivity in 33.6% of the bleaching days, which was significantly higher than the DG experimental group (20.1%) (P < 0.05).
This study was a long-term clinical trial of home and in-office LED and laser bleaching systems comparing for the first time interdental color differences (differences between the central labial surfaces of the canine and the central incisor). A total of 90 patients were divided into three groups of 30 each. One group received day guard vital bleaching, and the other two groups received one bleaching session for 20 min accelerated by a diode laser for 30 s per tooth or a blue LED for 3 min per tooth, and both groups received additionally day guard for 7 days. A total of four color measurements were carried out during the study period of 3 months and 3 weeks. The group treated with the LED tended to show the highest degree of equalization of lightness, chroma and hue. A significantly stronger overall increase in lightness was observed for canines after treatment when compared with incisors resulting in more homogeneous lightness values.