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Laser Teeth Bleaching: Evaluation of Eventual Side Effects on Enamel and the Pulp and the Efficiency In Vitro and In Vivo


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Light and heat increase the reactivity of hydrogen peroxide. There is no evidence that light activation (power bleaching with high-intensity light) results in a more effective bleaching with a longer lasting effect with high concentrated hydrogen peroxide bleaching gels. Laser light differs from conventional light as it requires a laser-target interaction. The interaction takes place in the first instance in the bleaching gel. The second interaction has to be induced in the tooth, more specifically in the dentine. There is evidence that interaction exists with the bleaching gel: photothermal, photocatalytical, and photochemical interactions are described. The reactivity of the gel is increased by adding photocatalyst of photosensitizers. Direct and effective photobleaching, that is, a direct interaction with the colour molecules in the dentine, however, is only possible with the argon (488 and 415 nm) and KTP laser (532 nm). A number of risks have been described such as heat generation. Nd:YAG and especially high power diode lasers present a risk with intrapulpal temperature elevation up to 22°C. Hypersensitivity is regularly encountered, being it of temporary occurrence except for a number of diode wavelengths and the Nd:YAG. The tooth surface remains intact after laser bleaching. At present, KTP laser is the most efficient dental bleaching wavelength.
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Review Article
Laser Teeth Bleaching: Evaluation of Eventual Side Effects on
Enamel and the Pulp and the Efficiency In Vitro and In Vivo
Roeland Jozef Gentil De Moor,1Jeroen Verheyen,1,2 Peter Verheyen,3Andrii Diachuk,1
Maarten August Meire,1Peter Jozef De Coster,1MiekeDeBruyne,
1and Filip Keulemans1
1Department of Restorative Dentistry and Endodontology, Ghent Dental Laser Centre, Ghent Dental Photonics Research Cluster,
Ghent University, Ghent University Hospital, Dental School, De Pintelaan 185-P8, 9000 Gent, Belgium
2Department of Clinical Neurosciences, John van Geest Centre for Brain Repair and Wellcome Trust-Medical Research Council
Stem Cell Institute, University of Cambridge, Cliord Allbutt Building, Cambridge Biosciences Campus, Cambridge, CB2 0QH, UK
3SOLA Academy, Bernhard Gottlieb University Clinic of Dentistry, Sensengasse 2A, 1090 Vienna, Austria
Correspondence should be addressed to Roeland Jozef Gentil De Moor;
Received  August ; Revised  November ; Accepted  November 
Academic Editor: Toni Zeinoun
Copyright ©  Roeland Jozef Gentil De Moor et al. is is an open access article distributed under the Creative Commons
Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is
properly cited.
Light and heat increase the reactivity of hydrogen peroxide. ere is no evidence that light activation (power bleaching with high-
intensity light) results in a more eective bleaching with a longer lasting eect with high concentrated hydrogen peroxide bleaching
gels. Laser light diers from conventional light as it requires a laser-target interaction. e interaction takes place in the rst instance
in the bleaching gel. e second interaction has to be induced in the tooth, more specically in the dentine. ere is evidence
that interaction exists with the bleaching gel: photothermal, photocatalytical, and photochemical interactions are described. e
reactivity of the gel is increased by adding photocatalyst of photosensitizers. Direct and eective photobleaching, that is, a direct
interaction with the colour molecules in the dentine, however, is only possible with the argon ( and  nm) and KTP laser
( nm). A number of risks have been described such as heat generation. Nd:YAG and especially high power diode lasers present a
risk with intrapulpal temperature elevation up to C. Hypersensitivity is regularly encountered, being it of temporary occurrence
except for a number of diode wavelengths and the Nd:YAG. e tooth surface remains intact aer laser bleaching. At present, KTP
laser is the most ecient dental bleaching wavelength.
1. Introduction
Heating hydrogen peroxide (HP) results in an acceleration
of its decomposition and oxidant-free radical formation [].
erefore, the dental bleaching process can be accelerated
by additional heat activation. One of the activation methods
gel is power bleaching with high-intensity light [].
e eectiveness of this method for vital tooth bleaching
has been demonstrated in animal studies, clinical studies and
reports, and a number of reviews []. Side eects for the
tooth, that is, alteration of the enamel surface, posttreatment,
Potential adverse eects on enamel were primarily inves-
Reports on the eects of light-activated systems were diver-
gent, which was also the case for conventional in-oce
bleaching techniques. On the one hand, changes in micro-
hardness, the presence of porosities, changes in surface
roughness, a reduction in fracture toughness, alteration of
the calcium/phosphate ratio, erosion, decrease in abrasion
resistance, and the formation of depressions were reported.
e enamel surface changes varied mostly with the bleaching
products used, especially high concentrations of hydrogen
peroxide; that is, –% (w/w) and % (w/w) carbamide
peroxide (CPO) (-% HP) could have a damaging eect,
whereas low concentrations % or % CPO (w/w) (–%
HP) had no eect []. On the other hand, rehardening of
porous enamel as a result of saliva ion reprecipitation has
been described. Although remineralisation due to the saliva
Hindawi Publishing Corporation
e Scientific World Journal
Volume 2015, Article ID 835405, 12 pages
e Scientic World Journal
may be responsible for a gradual mineral rebuild-up, full
repair of the enamel is not established due to a degradation
of the organic matrix []. To date, nevertheless, no clinical
Sensitivity aer bleaching is higher when HP is combined
with thermal activation []. Diverging results once again
have been published regarding the eect of power bleaching
on the pulp []. Also for this topic there is a lack of in vivo
studies and there are no studies evaluating long-term eects
of HP exposure on dental pulp.
An intrapulpal temperature increase of .Cisnowa-
days regarded as the threshold value, which should not
be exceeded to avoid irreversible pulp damage []. It
appears that temperature during light-activated bleaching is
in general under control, especially due to the presence of a
bleaching [,].
2. Aim
At present, there is no review on the eciency of laser
activated bleaching and its eect on the tooth (enamel and
inuence of the temperature rise during laser bleaching on
the pulp, the postoperative sensitivity, and eventual enamel
alterations. e eciency is evaluated on the basis of the
colour change in vitro and in vivo.
3. Methods and Materials
e electronic literature search included the databases
PubMed and Web of Science for manuscripts published with
full journal reference from January  to November .
All languages were accepted provided there was an abstract
in English. e following MeSH terms and key words were
used: “lasers” AND “tooth bleaching,” “lasers” AND “tooth
discoloration,” “tooth bleaching” OR “teeth bleaching” AND
(argon laser OR diode laser OR KTP laser OR Nd:YAG laser
OR Er:YAG laser OR Er, Cr:YSGG laser OR carbon dioxide
laser). Two reviewers (AD and BV) independently assessed
abstracts and full-text articles. First the reviewers considered
the abstracts as potentially relevant. Abstracts dealing with
this topic but without access to full journal article were not
taken into consideration. Case reports were included only
when they exclusively reported observations which were not
described in other publications. en full articles were read.
Both reviewers selected independently the same  full-text
articles; that is, Cohen’s kappa = ..
4. Results
4.1. Temperature Rise in the Pulp. Taking into account the
subject of the present review both power intensity and
wavelength of the light used during the bleaching procedure
mustbetakenintoconsideration[]. An overview of the
changes in temperature in the pulp during laser dental
bleaching is given in Table .
4.1.1. CO2Laser (10,600 nm). Luk et al. []reportedthat
the use of a CO2laser (, nm) on teeth for bleaching
purposes led to a temperature increase of . to .Cwith
gel at the enamel surface and . to .Catthepulpalside
of the dentine. Due to a lack of controlled clinical studies
this wavelength was not approved for bleaching by the ADA
[]. At present this wavelength is no longer used for dental
4.1.2. Nd:YAG (1,064 nm). Next to the CO2laser, the highest
temperature elevations in the pulp were registered with the
Nd:YAG laser (,nm) irrespective of the use of coloured
bleaching gels (blue, red, and transparent) [,].
4.1.3. Diode Lasers. High power diode lasers (– nm)
are also known to be able to rise the pulpal temperature
overview of the reported data is given in Table .
Laser activation with a  nm diode laser ( s,  W)
without bleaching gel may result in a temperature increase of
activation only .C temperature increase was recorded [].
With a  nm diode laser, there was an increase of
temperature with .CatW-sand.
 s [].Inthesamestudytemperaturerisewasloweraer
application of a bleaching gel; the decrease was product
related: By White gel (By Dental, Pistoia, Italy) at  W resulted
in a rise of .Candat.Wof.
HP (FGM Produtos Odontol´
ogicos, Joinville, Brazil) it was
acts as a selective absorber near the dental surface, preventing
light penetration into the internal tooth structure. Apparently
the composition of the gel is also important as the gel layer
was  mm thick in both investigations.
An increase of .Cwithadiode laser ( nm) ( W,
 s) and .CwithanEr:YAG(,nm)(mJ,Hz,
 s) was registered by Sari et al. []. e temperature in the
gel, however, was .Cforthediodeand.
e increase in the pulp chamber temperature with a
diode laser ( nm) used at  W- s is below the critical
C that is nowadays regarded as
the threshold value and which should not be exceeded to
prevent irreversible pulp damage []. In the same study the
diode laser at  W- s resulted in a temperature increase
up to .Cand.
C with  W- s; the importance of use
of the gel with appropriate thickness was emphasized by
measurements of the temperature at the surface:  W resulted
in C,  W in .C, and  W in .C.
Similar ndings were registered by Fornaini et al. []
where an  nm diode at  W during × s resulted in
heating of the gel up to .CandatW-× s up to .C.
A temperature increase of –Cand
observed when a  nm diode laser was used to activate
Opalescence Xtra (Ultradent Products, South Jordan, UT,
USA) and Opus White (Opus Dent, London, UK) for . W-
A mean increase of .Cinthepulpwasseenwithan
 nm diode used at  W- s [].
With a hydrogen peroxide bleaching agent, the mean
maximum pulpal temperature rise was .CforaLED,
e Scientic World Journal
T : Increase in temperature (C) in the pulp (without or with gel application) aer exposure to laser light.
Authors Wavelength Settings Bleaching gel Result/temperature
Luketal.,[] , nm (CO)
 mW
× sec/ sec
GT:  mm
Opalescence Extra
Quick White
Star Brite
Nypro Gold
Pulp without and with gel
+. +.
+. +.
+. +.
+. +.
Michida et al.,  [] , nm (Nd:YAG)
 mJ,  Hz (. W)
 sec
GT: . to  mm
Whiteness HP Pulp with gel
Dominguez et al.,  []
, nm (Nd:YAG)
 mJ,  Hz
× sec
GT:  mm
Ena White Power
Opalescence Endo
Pulp with gel
, nm (Er :YAG)
 mJ,  Hz
× sec
GT:  mm
Ena White Power
Opalescence Endo
Pulp with gel
 nm (diode)
. mJ,  Hz
× sec
GT:  mm
Ena White Power
Opalescence Endo
Pulp with gel
 nm (diode)
 mW
× sec
GT:  mm
Ena White Power
Opalescence Endo
Pulp with gel
Klaric et al.,  [] nm (femtosecond
 mW,  min
Unfo cused
GT: ?
Without gel
Vivastyle 
Vivastyle 
Vivastyle 
Enamel surface Pulp
+. +.
+. +.
+. +.
+. +.
+. +.
+. +.
 mW,  min
GT: ?
Without gel
Vivastyle 
Vivastyle 
Vivastyle 
Enamel surface Pulp
+. +.
+. +.
+. +.
+. +.
+. +.
+. +.
Sulieman et al., a []  nm (diode)
W, sec
GT:  mm
surface of the gel
Opus Mix bleaching
powder + % HP
Pulp without and with gel
+ +.
Kivanc¸etal.,[] nm (diode)
W, sec
GT:  mm
𝐷:mm By White (BW)
Whiteness HP
Pulp without and with gel
+. BW +
WPH +.
. W,  sec
GT:  mm
Pulp without and with gel
+. BW +.
WPH +
Sari et al. [], Epub 
 nm (diode)
𝐷:Whiteness HP
Pulp with gel
 nm (Nd:YAG)
 mJ,  Hz,  sec
Pulp with gel
e Scientic World Journal
T : C o nti nue d .
Authors Wavelength Settings Bleaching gel Result/temperature
Sulieman et al.,  []  nm (diode)
 sec
GT:  mm
surface of the gel
Opus Mix bleaching
powder + % HP
Surface Pulp without and
with gel
. +. +.
. +. +.
 +. +.
Fornaini et al.,  []
 nm (diode)
× sec—rest time
 min
 g carbopol (HP
concentration  to
Peak gel temperature
 nm (KTP)
× sec—rest time
 min
Peak gel temperature
Wetter et al.,  [,]  nm (diode)
. W,  sec
GT: ?
𝐷:mm Opalescence Xtra
Opus White (OW)
Pulp with gel
OPX +
OW comparable ()
GT: ?
Pulp with gel
OPX +
OW comparable ()
Eldeniz et al.,  []  nm (diode)
 W,  sec
GT: OPX?—QS:  mm
Opalescence Xtra
Quasar Brite (QS)
Pulp with gel
Zhangetal.,[] nm (diode)
. W,  sec
GT:  mm
𝐷:mm Hi Lite
Pulp with gel
 nm (KTP)
GT:  mm
Pulp with gel
Verheyen et al.,  []  nm (diode)
GT: ?
Opus White (OW)
Ti-O gel (TO)
Pulp with gel
OW 
TO 
Goharkhay et al.,  []  nm (diode)
GT: ?
Opalescence Xtra
Pulp without and with gel
+ 
+. +.
Pleen et al.,  []  nm (dio de)
 mW, × s ec
GT: ?
% experimental HP
In the gel Pulp with gel
+. +.
Carrasco et al.,  []LED-laser
/ nm
 mW, × sec
GT:  mm
Whiteness HP Pulp without and with gel
+. +.
Torres et al.,  []LED-laser
/ nm
 mW
× secc
GT:  mm
Whiteform Perox Red Critical temperature rise of .C
not reached
Coutinho et al.,  []
/ nm
/ nm
 mW, × sec
 mW, × sec Whiteness HP
Pulp with gel
Incisor +.
Canine +.
Premolar +.
Incisor +.
Canine +.
Premolar +.
GT: gel thickness; 𝐷: distance between light source and the bleaching gel.
e Scientic World Journal
.C for a KTP laser ( W- s), and .Cforanm
diode laser (. W- s) [].
WithanoutputpowerofW-sofannmdiode laser,
C with the Opus White gel (Opus Dent), whereas a TiO2
emulsion showed almost no temperature changes in the pulp
A treatment protocol with intermittent irradiation of six
times for  s, with  breaks in between, at a power setting
of less than  W, with a  nm diode laser excluded thermal
damage to the pulp, whereas the temperature at the surface
was C. Irradiation at  W with the same protocol resulted
in a temperature elevation of .C at the surface and .Cin
the pulp chamber [].
e addition of colorants mayhelptoprovideabetter
absorption of high power diode laser light in the bleaching
gel and less transmission towards the pulp chamber. Pleen
et al. [] demonstrated that a low-intensity red diode laser
( nm) ( mW- × s) with a green-coloured bleach gel
resulted in not more than a .C temperature elevation in the
pulp chamber.
It is clear that power and type (wavelength) of the light
source inuence temperature variation. Studies have shown
that near-infrared lasers could improve the inammatory
response of the pulpal tissue, reducing pulp damage and
relieving pain aer the bleaching process []. Its use would
diminish patients’ sensitivity complaints aer the procedure.
In this respect LED devices were associated with diode lasers
emitting in the near-infrared. According to Carrasco et al.
[] / nm ( mW- × s) temperature is under con-
trol. Other studies also demonstrated negligible temperature
changes: / nm ( mW- × s) [], / nm
( mW- × s), and / nm ( mW/ × s []).
Moreover it appears that these combination types of light
sources with low power density are not powerful enough to
provide a better bleaching ecacy as compared to other light
sources [,,].
A comparison between dierent laser wavelengths by
Dominguez et al. [] used as follows: that is, three bleaching
gels (transparent, with blue dye, with red dye, composition of
dye mentioned) exposed during  times for  sec to the light
source with a  min interval and an overall contact time of the
gel with the tooth surface during  min, demonstrated the
following temperature eects in decreasing order: Nd:YAG
( nm) (rise of .Cinthepulpchamber)>halogen
lamp ( nm) >low power diode ( nm) >low power LED
(– nm) >2𝜔Nd:YAG ( nm) >Er:YAG ( nm).
ese ndings coincided with the ndings of Torres et al. []
(halogen versus diode / nm) and Carrasco et al. []
(halogen versus diode / nm versus LED).
In a study of Klaric et al. [] a comparison was
made between ZOOM (– nm) during  min, LED
( nm) during  min, OLED (organic light emitting
diode) (– nm) during  min, and a femtosecond laser
( nm) (Millenia, Spectra Physics, USA) during min:
ZOOM resulted in high temperature elevations (+.C)
in the pulp whereas elevations were +.Cwithoutuseof
bleaching gel; the femtosecond laser focused: +.Cwithout
gel and +.C with gel; the femtosecond laser unfocused:
it has also to be mentioned that the mechanism of heat
conversion depends directly on the tissue constituents and
the irradiation wavelength used. It is known that the tooth
absorption coecient is lower for the wavelength range 
<𝜆< nm; thus scattering predominates over absorption
at these wavelengths.
Er:YAG (2,940 nm). In a study of Kivanc¸etal.[]tem-
perature increase in the pulp was neglectable. A very low
temperature rise of .C was registered by Sari et al. [].
KTP (532 nm). Using the green light of the KTP to irradiate a
red coloured bleaching gel resulted in a temperature of C
at  W during  sec and .CatWduringsec[].
With a hydrogen peroxide bleaching agent, the mean
maximum pulpal temperature rise was .CforaLED,
.C for a KTP laser, and .Cforadiodelaser[].
4.2. Inuence on the Characteristics and Material Properties of
the Teeth. eaimofableachingprocedureistobleachthe
tooth without morphological and chemical changes. How-
ever, side eects aer power bleaching in the enamel such as
changes in microhardness, the presence of porosities, changes
in surface roughness, a reduction in fracture toughness,
alteration of the calcium/phosphate ratio, erosion, decrease
in abrasion resistance, and the formation of depressions were
reported. Weakening of enamel structure by oxidation of
organic or inorganic elements is considered to be the main
cause [].
4.2.1. Morphological Analysis. Morphological analysis
showed slight changes with the diode laser ( nm) and
the LED/laser ( nm/ nm) []. Surface eects were
unrelated to the pH of the high concentration HP bleaching
gels with laser activation and referred more to a better
or lesser absorption of the laser light by the bleaching
gel. Chromophores and the use of TiO2appeared to be
favourable for the maintenance of an intact tooth surface
[]. No signicant eects on the morphology of the enamel
surface aer laser bleaching with diode laser, KTP, Nd:YAG,
and Er:YAG were observed by Dominguez et al. [].
4.2.2. Mineral Content. FT-RS results showed a decreased
mineral content aer bleaching procedures with and without
light activation and with % HP-based bleaching agents.
e use of a LED/laser ( nm/– nm) resulted in
comparable calcium loss as compared to the non-light-
activated bleach gels for  of  brands. Exposing Pola Oce
(Southern Dental Industries, Sao Paulo, SP, Brazil) to the
LED/laser did not result in a signicant calcium loss []. An
explanation for this dierence was not given.
No signicant dierences in levels of calcium and phos-
phorus were seen aer / nm LED/laser bleaching [].
In a study of Cesar et al. []with%HP-basedbleach-
ing agents activated with a LED/laser (. nm/ nm),
FT-Raman spectroscopy data showed no signicant chem-
ical changes in the inorganic components for the tested
e Scientic World Journal
groups. Carbonate and phosphate area peaks were not signif-
icantly changed. Whiteness HP Maxx (FGM Produtos Odon-
ogicos Ltda., Santa Catarina, Brazil) and Opalescence Xtra
(Ultradent Products) were also tested in the study of Berger
et al. []. ere was a signicant reduction of the dental
organics associated with type I collagen vibration only in
the group of Whiteform-Perox Red gel (Formula & Acao,
Sao Paulo, SP, Brazil). is means that there is a dierence
between both studies. Total contact time of the gels was
identical, that is,  consecutive gel applications for  min.
Irradiation protocols, however, diered: in Berger et al. [],
there was a bleaching gel le on third molars undisturbed
for  min and then irradiated for  min; the light irradiation
was repeated  times with a  min interval between radiations;
in Cesar et al. [] there was photoactivation of the gel
for  sec for a total of min of application on bovine
teeth. Moreover, similar dierences in ndings were also
observed with non-light-activated high concentration HP
bleaching gels. Whether the dierences found for the present
two studies are related just to the bleaching protocol is not
clear yet; in fact dierences in oxidizing potential (stronger),
stronger concentrations, longer treatment times, and lower
pH of bleaching gels could be responsible for the changes
found in the studies [].
( nm,  mW power) it was seen that the enamel crys-
tallinity was dramatically decreased by a bleaching treatment
without laser irradiation. However, crystallinity increased
as laser irradiation time increased. It was concluded that
professional bleaching treatment with HP combined with a
diode laser irradiation not only improves the bleaching eect
but also protects against the change of enamel structure com-
pared with the bleaching treatment without laser irradiation
TEM analysis showed the formation of a new phase  𝜇m
property of the bleaching gel could have been changed
through exposure to laser irradiation. It can also be that this
phenomenon accounts for bovine teeth where the enamel
contains signicantly more interprismatic organic material
compared to human enamel even though its structure and
compositions are very similar to those of human enamel.
4.2.3. Microhardness. e microhardness test is suitable for
determining small changes in surface that demonstrated the
A comparison between argon laser ( nm,  mW,
 sec irradiation and -minute intervals during  min) and
and -minute intervals during  min) did not result in
dierences with the control group using % and % CP
Zhang et al. [] showed no dierences between the
control (% HP) and KTP (W,  sec, energy density (ED)
. J/cm2), diode  nm (.W,  sec, ED: . J/cm2),
and blue LED composite curing lamp ( nm,  s, ED:
. J/cm2) experimental groups. Diode laser ( nm) irra-
diation ( times,  sec irradiation at . W of newly placed)
with microhardness [].
Reduction in microhardness was found aer bleaching
with a LED/laser (/ nm, light intensity of  mW,
 min laser activation of the gel, followed by -minute rest; this
procedure was repeated  times), which recovered to baseline
values aer  week of immersion in articial saliva [].
4.2.4. Enamel Permeability. Higher permeability of the
enamel surface aer a bleaching procedure with a LED/laser
(– nm) and QTH light as compared to a control
(% HP) was reported; there were no signicant dierences
between the two bleach protocols [].
Bleaching with a / nm LED/laser did not show
penetration [].
4.2.5. Caries Susceptibility of Bleached Enamel. In-oce laser
bleaching with a LED/laser ( nm) does not result in a
higher susceptibility for caries lesions [].
4.2.6. Fracture Strength. Araujo et al. []showedthata
LED/laser (. nm/ nm) did not inuence the fracture
strength of enamel aer light-activated bleaching.
4.2.7. Bonding to Bleached Enamel. Bonding to intracoronally
light-activated bleached dentine should be performed at
least  days aer a bleaching procedure with a LED/laser
(. nm/ nm) []. A time interval of  to  weeks was
advocated for applying silorane-based composite restorations
of methacrylate based composites aer bleaching with an
 nm diode laser []. A week interval aer bleaching
with an  nm diode and – nm blue LED showed
to the control and bleaching with QTH light (– nm)
the diode laser (%) and the LED (%); for both the
control group and the QTH lamp the failure mode was mixed
(adhesive and cohesive) (%).
4.3. Hypersensitivity
4.3.1. Diodes and LED/Lasers (Diodes). Sensitivity is
described by some as common with the diode laser.
Bleaching with a diode laser ( nm, % HP) just reached
the level that can be tolerated by the patient []. Comparing
a diode laser ( nm, % HP) with PAC activation (–
 nm, % HP), LED activation (– nm, % HP)
and no light activation (% HP) resulted in the lowest
sensitivity for the diode laser [].
In the study of Kossatz et al. [] .% of the participants
had sensitivity even  hours aer laser bleaching with a
LED/laser unit ( nm/ nm, % HP) with a protocol
of gel activation during min, leaving the gel undisturbed
during  min and repeating this protocol  times and the
in-oce bleaching agent was refreshed every  minutes
during a -minute application period. Immediate sensitivity
was also scored in the study of Mondelli et al. []witha
LED/laser ( nm/ nm, % HP). Sensitivity decreased
e Scientic World Journal
aer  hours to return to normal aer  days. ere were
no dierences between in-oce gels (light- and non-light-
An increased expression of substance P was seen when a
LED laser ( nm, % HP) was used [].
More recent studies demonstrated that sensitivity was
generated independently of the light sources used: Almeida
et al. [] with a LED/laser at –/ nm, Martin et al.
[] with a LED/laser at / nm, and Moncada et al.
[] with a LED/laser at –/– nm. e latter
two studies demonstrated a higher impact of the increase
in concentration of bleaching agents on tooth sensitivity;
treatment with carbamide peroxide generated also lower
sensitivity than treatment with HP independently of the light
A comparison between all these studies is dicult and
impossible because each investigation is dierent, that is,
dierent protocols. Moreover, complete basic information,
that is, power settings, gel thickness, distance between gel,
and light source, is not provided in the listed studies.
4.3.2. Nd:YAG. When using the Nd:YAG laser (, nm,
% HP) for laser bleaching at  W,  Hz,  𝜇spulsedura-
tion, and an energy density of . J/cm2in association with
a red coloured gel, no enhancement of the bleaching success
was found []. ere was no reduction in hypersensitivity,
dentinal hypersensitivity. Only % of the patients in this
study had a pain-free treatment with the Nd:YAG laser. e
remaining patients felt the development of warmth to the
point of pain, even a few days aer laser treatment. e
authors concluded to query the appliance of Nd:YAG laser
irradiation for in-oce bleaching.
4.4. Laser Bleaching: Tooth Colour Change and Eciency
4.4.1. Colour Change In Vitro. A comparison based on
analysis of photoreectance spectra between the use of an
argon laser ( nm) and halogen lamp with % and %
CPO gave better results for the % CPO gel. Halogen was
as eective as argon laser with % CPO; argon was more
eective than halogen for the % CPO []. A compari-
son between LED/diode laser (– nm/ nm), argon
( nm), PAC (– nm), and halogen (– nm)
showed better results for a % HP than for % CBP.
A decrease in reectance values was seen aer  days;
no dierence was observed in bleaching eciency between
activated and nonactivated bleaching gels with high HP
concentrations [].
In a study comparing KTP ( nm, % HP) with a
improved changes in brightness of up to ten steps on the
Vitapan classical shade guide were detected. Prerequisites,
however, were a perfect match of the chosen wavelength and
the bleaching gel. A neutral and basic pH of the bleaching
gel is also advantageous. e higher bleaching power of KTP
as compared to an  nm diode laser was conrmed by
Fornaini et al. [].
Diode laser activation ( nm, % HP) of the bleaching
agent was not more eective than the halogen lamp for
bleaching root canal treated primary molars [], safer for T
development. Activation of a % HP bleaching gel by diode
laser ( nm, % HP) as well as a xenon halogen light, a
plasma arc lamp, and halogen light did not dier in result
from the use of the same gel without light activation [].
A comparison between a  nm diode laser and a xenon
arc lamp (– nm) used with a % HP bleaching gel
showed that there was an increase in colour saturation (Δ𝐶)
of –% and a change in whiteness (Δ𝐿)of –% []. e
highest ecacy was achieved with the diode laser at  W, the
lowest with the diode laser at .W. However, due to the risk
of higher temperature development, the authors considered
the xenon lamp as the safest. A comparison between a diode
laser ( nm) and LED (nm) demonstrated signicant
comparable change in chroma for the two % HP bleach gels
change in lightness for all test conditions, but the diode scored
signicantly best with the Whiteness HP bleaching agents
(FGM Produtos Odontol´
ogicos, Joinville, Brazil) than with
Opalescence Xtra (Ultradent Products) [].
A comparison between dierent laser wavelengths by
Dominguez et al. [] demonstrated that the source of irradi-
ation was more relevant than the bleaching agent for ecient
tooth bleaching. ey exposed three % HP bleaching gels
(transparent, with blue dye, and with red dye, composition of
dye mentioned) during  times for sec to the light source
with a  min interval; contact time of the gel with the tooth
surface was  min. LED (– nm, low power), halogen
lamp ( nm), and diode ( nm, low power) produced
Nd:YAG ( nm), Er:YAG ( nm), and 𝜔Nd:YAG
( nm). e mean improvement in tooth whiteness with
the latter three wavelengths is in the same order as without
photoactivation. It is thus the question if these wavelengths
dier from other studies where the eect of an Nd:YAG was
comparable with a halogen light [], and the eect of KTP
was better as compared to diode (nm) and blue LED
( nm) [], but these chromophores were chosen as a
function of the wavelength used (Nd:YAG: Q-switch dye with
maximum absorption at  nm) (KTP: sulphorhodamine B
with maximum absorption at . nm).
4.4.2. Clinical Ecacy. When the Nd:YAG laser (% HP)
was used for bleaching, Strobl et al. [] found no supportive
inuence of the laser radiation on the bleaching. e authors
registered a change in the colour of the bleach gel aer
laser activation, being a result of the increased formation of
chemicals radicals, but could not explain why this does not
e use of a low-intensity red diode laser ( nm, %
HP) with a green-coloured bleach gel resulted in a change of
colour (Δ𝐸 wasincreasedfrom.to.aerweek)[].
Overall shade change values recorded by spectropho-
tometer reading expressed as Δ𝐿,Δ𝑎,Δ𝑏,andΔ𝐸 were sig-
nicantly higher for diode laser ( nm, % HP) bleaching
than PAC activation (– nm, % HP), LED activation
e Scientic World Journal
(– nm, % HP), and no light activation (% HP),
although shade guide evaluations did not exhibit any dier-
ences []. One session of  min of in-oce bleaching with
or LED ( nm, % HP) ( min irradiation to each group of
teeth) or diode laser ( nm, % HP) ( sec irradiation
during  days was not more eective than % CP home-
bleaching alone during  days [].Bleachingwithannm
diode laser and % HP showed greater shade improvement
for teeth with hue A shade than those with hue C and D. e
bleaching process is better in younger patients and gender is
not a factor that aects the bleaching process [].
LED/laser at  nm (one wavelength mentioned) did not
show any improvement in bleaching result for the treatment
of vital teeth as compared to halogen light, LED, and non-
light-activated % HP. All treatments resulted in an increase
of Δ𝐸 (best score for the non-light-activated protocol), which
was maintained for  month and then dropped at  months
(from on average  at  month to . at  months for the
light-activated systems and from . to . for the non-
light-activated group) []butalsomeaningthattherewas
only a slight colour rebound. LED/laser (nm/ nm)
did not improve the in-oce bleaching results with % HP
as compared to QTH (quartz-tungsten-halogen) light and at
home bleaching with % CPO []. A change in colour was
registered for all protocols, which was maintained over a -
month period []. In another investigation LED/laser (–
 nm/ nm, % HP) did not improve the bleaching
eectiveness during any phase of the study []ascompared
 nm at  mW, % HP) and additional sessions did not
improve the results obtained in the rst session. Change of
color was registered for all systems. In a study by Mondelli
et al. []in-ocebleaching(%and%HP)withand
without activation with a LED/laser ( nm/ nm) was
compared with home bleaching (% CPO). All techniques
and bleaching agents were eective. ere was no dier-
ence in Δ𝐸 between non-light- and light-activated in-oce
treatment. e initial increase in Δ𝐸 decreased over a time
period of  months (from on average . to  for the high
concentration HP, from . to . for the home bleaching
procedure with % CPO).
Visible green light KTP laser ( nm, % HP) com-
bined with sulphorhodamine B-photosensitizer bleaching
gel activated for  sec at  W provided a clinically useful
improvement in tooth shade in teeth with tetracycline discol-
orations [,]. KTP was more ecient than a  nm diode
laser for the removal of discolourations due to red fruits,
tea, and coee []. KTP is more ecient for tetracycline
discolouration than a high powered green LED for the
bleaching of tetracycline-stained dentine [].
5. Discussion
Light sources are marketed with the idea that light plays a
signicant role in tooth bleaching as catalyst for the ioniza-
tion of HP in the bleaching gel and increasing the bleaching
eect. Studies on light sources with incoherent light sources
have produced contradictory results, but the following con-
clusions were drawn on the basis of a systematic review: ()
both light-activated and non-light-activated systems showed
similar immediate and short-term bleaching eects when
high concentrations of HP (–%) were used as bleaching
gel; () there is limited evidence that a light-activated system
produced better immediate bleaching ecacy than when
non-light-activated systems with a lower concentration of HP
(–%) were used [].
Two key factors determining overall tooth bleaching
ecacy from peroxide containing gels are the concentration
of the HP and the duration of application.
For as far as the specic topic of laser activated bleaching
is concerned, contradictory results are found as was also seen
with conventional bleaching procedure using high hydrogen
peroxide concentrations. In addition, the number of laser
activated bleaching studies is limited as compared to the
literature on light-activated bleaching. Comparisons between
the eects of dierent wavelengths are dicult to make: ()
for laser bleaching absorption in the bleaching gel is aimed
to drive the ionization of the HP; this depends on the specic
wavelength needed to directly photolyze or photooxidate the
chromophores in the dentine; () the chosen wavelength
has to coincide with the absorption peak of chromophores
or photocatalysers in the bleaching gel (if present) in order
to catalyse the ionisation of the hydrogen peroxide and to
drive the photolysis; () there is the heterogeneity of the
heating temperature of the gel, that is, the photothermal eect
which is even so inuenced not only by the wavelength,
but also by the specic power settings; () because of the
previously mentioned heterogeneity of the laser settings, seen
when a specic laser wavelength is considered, the bleaching
gel must be developed taking into account the specic
laser wavelength; () in addition, power density or energy
density (uence) of the laser beam is important; temporal
characteristics of the laser beam are to be considered such
as continuous versus pulsed delivery and consequently the
dierences in the method of energy transfer such as contact
versus noncontact delivery mode, focused versus unfocused,
least there are the dierences in the exposure time of the gel
to the laser light and the specic bleaching protocol (e.g., one
exposure or consecutive exposures of a fresh bleaching gel do
also contribute to the heterogeneous data).
In general, laser bleaching is performed with a hand
piece or a bre in noncontact mode, unfocused, and with
continuous emission. Regarding the power or energy, high
power lasers are generally used, except when bleaching is
performed with the argon laser ( or . nm) or with a
, , or  nm diode laser.
All studies selected for this survey on laser bleaching have
in common the fact that a high HP concentrated bleaching
gel is used ( to % HP and  or % CP, i.e.,  to %
HP). None of the clinical studies used low concentrations
of HP. For HP concentrations of %, it is known that light
activation produced better immediate bleaching eects [].
e EU Council Directive //EU of September , 
[], restricts the use of bleaching and bleaching products:
e Scientic World Journal
bleaching products that contain or release between .% and
% HP and products for tooth bleaching and bleaching that
contain or release up to .% HP are available as over-the-
counter products. Products with HP concentrations over
% are prohibited as cosmetics. is clearly means () that
products containing or releasing more than % are prohibited
for dental bleaching and () that dental bleaching is not
considered as a medical action but only as cosmetical and
hence nonhealing procedure. Information on laser activation
A number of wavelengths can be considered as not rec-
ommended for laser bleaching: Nd:YAG (, nm), Er:YAG
(, nm), and CO2(, nm). e eect of these laser
wavelengths is purely based on heating of the bleaching gel
(Nd:YAG) or should only be restricted to heating of the
bleaching gel (Er:YAG and CO2: care has to be taken not to
remove tooth substance with Er:YAG and CO2because both
wavelengths are well absorbed by water and hydroxylapatite
which might result in supercial ablation of tooth substance).
Although the CO2-laser received an FDA approval for
bleaching, the ADA soon aer recommended not to use this
wavelength for bleaching.
From all bleaching wavelengths the diode wavelengths
have been most extensively investigated. A large range of
diode wavelengths are used as laser bleaching wavelengths.
ese near-infrared lasers are used at low power or at high
power. Both low power and high power diode lasers do not
result in an enhanced bleaching ecacy when compared to
non-light-activated bleaching with high HP concentrations.
e question is even if low power diodes aid in the activation
of the bleaching gel. Care, however, has to be taken with the
high power diodes so as not to heat the bleaching gel at a level
at which thermal damage of the pulp might occur.
Another key factor to increase the rate of the chemical
reaction is to increase the temperature, where a rise of C
can double the reaction rate. On the one hand the thickness
of the bleaching gel layer is important to ensure that the
laser light can pass through this layer. e distance between
the energy is considered. Laser interaction is not limited to
the gel alone and laser light has also to interact with the
discolouration in the tooth.
Adding chromophores, chosen in accordance to the
absorption peak of the gel, acts as a selective absorber near the
dental surface, preventing light penetration into the internal
inuences the nal temperature, since dierent light sources
have dierent emission wavelengths and the absorption peak
changes following gel colour. Also here the question is if the
dyes added for photoactivation of the gel with diode lasers
are helpful in activating the bleaching gel. With high power
diode lasers, irrespective of the thickness of the bleaching gel,
care has to be taken still so as not to extensively dehydrate the
Recently LED devices were associated with diode lasers
emitting in the near-infrared, which, with appropriate energy
density, are being used to desensitize the teeth under
bleaching [,]. ese studies demonstrated that near-
pulpal tissue, reducing pulp damage and relieving pain aer
the bleaching process. e use of these devices (so-called LED
lasers), however, did not result in any increased bleaching
ecacy. us the question is to what extent these low power
diodes are of help in the bleaching process.
Light-activated systems were found to increase the occur-
rence of severity of tooth sensitivity []. e light source
itself can increase pulpal temperature leading to increased
tooth sensitivity []. e latter was also encountered with
diode lasers [,] and Nd:YAG [,,]. For both
wavelengths laser light is transmitted through the bleaching
gel in combination with a heating of the gel, irrespective of
the thickness of the gel leading to tooth sensitivity [,,
,]. An additional explanation is also that laser activated
bleaching may increase the expression of substance P in the
human dental pulp [,].
Taking into account all dierent wavelengths used for
laser activated bleaching, the KTP laser when used at
appropriate settings and combined with the red coloured
bleaching gels (Smart Bleach, SBI) has been shown to be
one of the best options for photoactivated dental bleaching.
Wals h [ ] demonstrated a higher bleaching eect with KTP
than with a diode laser based on DOTCAM analysis, a
result which was also conrmed in other studies [,,
]. Its ecacy was also demonstrated for the bleaching of
tetracycline discoloured teeth []. Temperature elevation in
the pulp chamber was also under control when appropriate
settings were used in conjunction with a red coloured gel
(containing sulphorhodamine B as a chromophore) [,
]. e safety of the procedure was demonstrated by an
unaltered enamel surface aer KTP laser bleaching []; no
signicant dierences in the enamel microhardness pre- and
posttreatment [] and no changes in the compositional
structure of dentin surfaces were found []. Occasional mild
postoperative sensitivity was seen during the h following
pulpal enzymes [,]. Catalase had been found to protect the
dentalpulpduringvitalbleachingprocedures[]. A catalase
application was demonstrated to eliminate residual hydrogen
peroxide during non-vital bleaching procedures [].
6. Conclusions
() It is dicult to draw conclusions for laser bleaching
on eciency and ecacy from the present-day lit-
erature because of the dierence in concentrations
in hydrogen peroxide used, the dierence in wave-
lengths of lasers (especially the diodes) used, the
dierence in laser settings and protocols used, and
dierences in bleaching gels used with or without
() Comparative studies evaluating bleaching techniques
with high concentrations of hydrogen peroxide and
with or without the use of light activation resulted in
enhanced lightening. Most oen comparable results
were found irrespective of light exposure.
 e Scientic World Journal
() No long-term evaluations for laser enhanced bleach-
ing procedures are available.
() Based on the limited number of investigations, at
present, only one particular wavelength appears to be
dation), that is, KTP ( nm). When KTP is used in
combination with a bleaching gel containing a chro-
of the laser light, photodynamic reactions can be
induced (photochemical activation of the gel with
limited photothermal activation). is combination
of wavelength and specically dyed bleaching gel also
allows for safe bleaching (no damage of the enamel,
no heating of the pulp) when the guidelines of the
manufacturer are followed.
mended for laser bleaching: Nd:YAG, Er:YAG, and
CO2. Combination devices consisting of LED-diode
laser do not result in enhanced lightening and are in
fact not eective. When using high power diode lasers
for bleaching care has to be taken so as not to overheat
the pulp. Also diode lasers are not really advocated
for laser bleaching except when the wavelength is
used in combination with a bleaching gel containing
wavelength specic absorbers.
() With the exception of KTP used in combination with
(sulphorhodamine B) for the green light ( nm),
the bleaching gel.
() All studies have been conducted with high concen-
trated hydrogen peroxide gels. is means that the
so tissues have to be thoroughly protected during the
in-oce power bleaching procedure. No studies were
conducted to investigate the safety of laser bleaching
procedures on the so tissues adjacent to the laser
activated bleaching gel.
7. Recommendations for Future Investigations
ree factors are to be considered when using a light source
and should be mentioned in the studies: light intensity,
spectral distribution, and irradiation time. Since the total
energy depends on light intensity and irradiation time, light
curing units with high intensity may allow a reduction in
irradiation time. Second generation LEDs present higher
power than rst generation LEDs. Further research is needed
to evaluate if high power (narrow band) LEDs can be used for
light-activated bleaching. With the price of a number of laser
devices in mind, this technology might be of interest for the
activation of bleaching gels.
An important relationship exists among gel colour, laser
wavelength, thermal transmission, and clinical ecacy, but
not between gel temperature, shade change, and HP concen-
tration. In this respect the use of absorbing substances to
increase the radiation absorption (and the temperature in the
gel) is known. With the use of TiO2it has been demonstrated
that there is another way to improve dental bleaching without
the risk of damaging the pulp. Hence the composition of
the gel with the absorbers and additional compounds (agents
enabling to catalyse the redox reaction) should also be given
in detail.
Conflict of Interests
e authors declare that there is no conict of interests
regarding the publication of this paper.
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... Já o laser de Diodo, quando utilizado durante tratamento clareador, trabalha em comprimento de onda entre 800 a 980nm na faixa do infra-vermelho, com alta absorção por tecidos pigmentados 31 . A grande limitação do uso desses aparelhos é oriunda da indução do aumento de temperatura no substrato alvo através do seu efeito fototérmico 38,39 . ...
... A absorção dos pacotes de energia ou fótons influencia no aumento de temperatura do gel clareador e/ou dos tecidos pulpares 39 . De acordo com De Moor et al. 38 , a adição de certos corantes ao agente clareador pode viabilizar uma melhor absorção da luz e menos transmissão de calor para a câmara pulpar. O uso do gel de cor específica serve como um filtro para proteger a polpa da luz infra-vermelha 31 . ...
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Objetivo: O objetivo do estudo foi realizar uma revisão de literatura sobre a efetividade das fontes luminosas empregadas no tratamento clareador de consultório. Métodos: Os artigos selecionados foram pesquisados nas bases de dados: Pubmed (MEDLINE), Scielo e Lilacs, com os descritores “clareamento dental”, “luz” e “peróxido de hidrogênio”, publicados no período de 2010 a 2021, nas línguas portuguesa e inglesa. Resultados: Foram encontrados resultados conflitantes na literatura, porém estudos mais recentes demonstram que as luzes não são imprescindíveis durante o clareamento dental. Considerações finais: De acordo com trabalhos mais recentes, dentes clareados são oriundos do contato direto do peróxido de hidrogênio à estrutura dentária, portanto sugere-se que não há a necessidade da utilização de fontes luminosas durante o tratamento clareador. Contudo, mais estudos são necessários, a fim de proporcionar uma fundamentação com embasamento científico que sirva aos profissionais clínicos.
... Hydrogen peroxide is optically transparent; therefore, without adding a coloring agent, one cannot expect it to absorb visible or near-infrared laser light to any great extent. By choosing appropriate chromophores, a range of processes can be triggered [18]. Argon, KTP (potassium titanyl phosphate), and diode lasers are most commonly used for this purpose. ...
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Aim: The present study investigated the effects of laser and conventional in-office bleaching, and polishing on the color of stained composite resin. Materials and methods: A microhybrid composite (Clearfil AP-X) and a nanohybrid composite (Grandio) were selected. Twenty-four discs (2 × 10 mm) for each composite were prepared. The samples were immersed in coffee solution (25 g of coffee in 250 mL water) for seven days. Then the samples were divided into three groups (n = 8) and the stains were removed using bleaching (with Opalescence Xtra Boost), diode laser irradiation with Heydent material and a Sof-Lex polishing kit. The L ∗a ∗b ∗ color parameters were determined using a spectrophotometer before and after immersion and after stain removal procedures, and the overall color changes (ΔE) were calculated. The data were analyzed with two-way analysis of variance. Results: In the Clearfil composite resin group, the mean ΔE compared to the baseline using in-office bleaching, laser irradiation, and Sof-Lex polishing kit were 3.31, 3.35, and 4.93, respectively. These values with the Grandio composite resin were 3.31, 6.35, and 4.57, respectively. The highest capacity to remove stains was related to the conventional in-office bleaching method. Grandio composite resin underwent more color changes than Clearfil composite resin significantly (P-value < 0.05). Conclusion: Both composite resins exhibited color changes after immersion in the discoloring solution. However, after staining-removing procedures, the ΔE values decreased. Decreases in the ΔE values were not sufficient to restore the color to that before immersion in the discoloring solution with any stain-removing methods.
... The advantages for in-office bleaching include brighter white smile in less period of time, of course under a professional assistance with no or less damage to soft tissues of the teeth. (26,27) The disadvantages are basically the duration and cost of the treatment along with minor sensitivity issues patient experience for some first days of the tooth whitening procedure. (28) The benefits of home bleaching are the simplest easiest application of the material with no chair-side appointment and lower concentration of the bleaching agent. ...
Imitation of smile aesthetics and analysis, is an initial step for dental bleaching, hence it is significant that the dentist/dental hygienist identifies how to analyze the root causes of color change and to specify whitening before suggesting the suitable dental procedure. With the high-tech advancement, dental bleaching techniques have arose to assist its use and provide comfort, safety and reduction in time, in the performance of the technique. The conservative means of external dental whitening is with hydrogen peroxide (photo activated or not) or carbamate. However, dental sensitivity is frequently complained by patients by the home and office whitening procedures. There is an innovative bleaching application in the market without the use of these bleaching gels, as a consequence decreasing post-treatment sensitivity. Such a suggestion elucidates, replacing bleaching agent by ultraviolet light. The object of this literature review is to enlighten the determining factors that affect the final satisfactory results of the different techniques and explains a general overview, permissible to reach a treatment conclusion based on evidence. Keywords: tooth whitening, tooth bleaching, types of tooth bleaching, procedures of tooth whitening
... The term bleaching defines about changing color substances within tooth structure and also makes teeth lighter than its natural color [1] . Bleaching plays an important role in esthetics and helps to remove extrinsic and intrinsic stains [2]. ...
Background: Vital bleaching is most requested cosmetic dental procedure asked by patients who seek pleasing smile. Laser helps to reduce the stain and helps in teeth whitening. Aim: To investigate the effect of laser therapy induced by teeth bleaching. Methodology: A Literature review was performed using PubMed, Medline, PMC, Grey literature, Cochrane, Prospero, Wiley online library using MeSH term laser and teeth bleaching. Of a total 1658 appeared from various sources; all articles were screened and 14 were related to the research question and 5 were selected for the study. This review was reported according to PRISMA guidelines. Result: In the five studies of our systematic review shows that laser used in the case of teeth bleaching with higher concentration of hydrogen peroxide produced better result and comparatively lesser sensitivity than any other bleaching agents or lesser concentration of hydrogen peroxide. Conclusion: Clinical trials suggests that laser used in bleaching the tooth has better efficacy on tooth surface which resulted in lesser sensitivity and better tooth color, at the same time effectiveness of the treatment is same as that of the normal procedure.
... Efforts have been made in order to find solutions to prevent and manage dental sensitivity related to this treatment, such as the use of potassium nitrate and fluoride during and after the bleaching process, and the use of 2-hydroxyethyl-glutaraldehyde (G2H) with peroxides (1,9). Other solution that has been provided is to avoid the use of light sources, taking into consideration that there is not enough evidence to support the idea that light activated systems used in-office drift in better immediate results (11)(12)(13). ...
Background: Dental sensitivity is a common secondary effect related to vital tooth whitening (VTW) treatment and it’s associated with the concentrations and time of application of the bleaching agents. The aim of this research was to evaluate the relationship of dental sensitivity and the combinations of different concentrations of peroxides [hydrogen peroxide (HP) 10%/HP 40%] in order to define a tooth whitening protocol that is effective, while minimizing the discomfort experienced by patients. Methods: A cross-sectional retrospective study was carried out based on secondary de-identified data of 27 patients collected from a previous VTW clinical trial. The days of dental sensitivity and levels of sensitivity were measured. Descriptive statistics and the Pearson correlation coefficient were calculated. A level of significance P<0.05 was established. Results: The mean values obtained for the variables “day of dental sensitivity” and “levels of sensitivity” were 1.0741 (SD =0.91676) and 0.8148 (SD =0.62247), respectively. The Pearson correlation (r) obtained was 0.766, 95% CI: 0.55, 0.89, P=0.01. Conclusions: The findings indicate that dental sensitivity when occurs during or after VTW with HP 10% and HP 40% tends to be mild and does not last more than a day. The clinical implications and recommendations indicate that clinicians can safely use the treatment and that patients must be informed that dental sensitivity due to VTW may occur. Keywords: Tooth whitening; hydrogen peroxide (HP); tooth sensitivity; tooth bleaching; dental esthetics
... Diagnosis of a wedge-shaped defect is most often carried out at the later stages of its development, and treatment is carried out without taking into account the pathogenetic mechanisms of its onset and consists in excision of damaged tooth tissues with subsequent restoration [13][14][15]. Therefore, dental interventions are aggressive and often lead to complications and adverse outcomes [8,9]. ...
Background. Over the past 20 years, the prevalence of wedge-shaped defects has increased by 14%, and in some countries of the world it reaches critical values - 82%. At the same time, the treatment of this pathology is carried out at the later stages of its development with excision of the hard tissues of the tooth and subsequent restoration, without taking into account the initial macro- and microstructural changes in the enamel. The purpose of our study was an experimental in vitro study of anatomical and morphological features of the tooth enamel structure, its qualitative and quantitative composition in the initial forms of a wedge-shaped defect. Materials. As the material for our study we used intact teeth removed for orthodontic indications and with initial forms of a wedge-shaped defect of classes 1 and 2 according to the classification of Shevelyuk Yu.V., Makeeva I.M. (2011), subsequently 63 sections were made out of these teeth. Methods: clinical, experimental, scanning electron microscopy and energy dispersive analysis, statistical, analytical. Results. Structural transformations of enamel were revealed in the initial forms of the wedge-shaped defect, the boundaries of the lesion were determined, and morphological changes were established in the tissues adjacent to the lesion involved in the pathological process against the background of quantitative and qualitative indicators of its chemical composition. Conclusion. a comparative analysis of the enamel microstructure in normal and wedge-shaped defects confirms the heterogeneity of the lesion and the transformation of the chemical, quantitative and qualitative composition of the enamel.
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Modern dentistry is increasingly turned towards an esthetic, conservative and minimally invasive sense in order to obtain satisfactory results for both the patient and the operator. The clinician must frequently face the presence of chromatic alterations (discoloration) of the dental elements and fewer times several pigmentations of gums and oral mucosa. Such chromatic alterations of both hard and soft tissues are often experienced by the patient as disabling, with important repercussions from a psychological point of view and in the life of relationships.[1.2] Several laser devices with specifical wavelength can be employed in a minimally invasive way to solve the above mentioned aesthetic disease. Different laser techniques of oral dental and gum whitening, performed by acknowledged authors worldwide will be described in light of most recent and significative scientific literature.
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In recent years, the application of lasers for modifying the surface topography of dental biomaterials has received increased attention. This review paper aims to provide an overview of the current status on the utilization of lasers as a potential tool for surface modification of dental biomaterials such as implants, ceramics, and other materials used for restorative purposes. A literature search was done for articles related to the use of lasers for surface modification of dental biomaterials in English language published between October 2000 and March 2023 in Scopus, Pubmed and web of science, and relevant articles were reviewed. Lasers have been mainly used for surface modification of implant materials (71%), especially titanium and its alloys, to promote osseointegration. In recent years, laser texturing has also emerged as a promising technique to reduce bacterial adhesion on titanium implant surfaces. Currently, lasers are being widely used for surface modifications to improve osseointegration and reduce peri-implant inflammation of ceramic implants and to enhance the retention of ceramic restorations to the tooth. The studies considered in this review seem to suggest laser texturing to be more proficient than the conventional methods of surface modification. Lasers can alter the surface characteristics of dental biomaterials by creating innovative surface patterns without significantly affecting their bulk properties. With advances in laser technology and availability of newer wavelengths and modes, laser as a tool for surface modification of dental biomaterials is a promising field, with excellent potential for future research.
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Highly processible graphene oxide (GO) has a diversity of applications as a material readily dispersed in aqueous media. However, methods for preparing such free-standing GO use hazardous and toxic reagents and generate significant waste streams. This is an impediment for uptake of GO in any application, for developing sustainable technologies and industries, and overcoming this remains a major challenge. We have developed a robust scalable continuous flow method for fabricating GO directly from graphite in 30% aqueous hydrogen peroxide which dramatically minimises the generation of waste. The process features the continuous flow thin film microfluidic vortex fluidic device (VFD), operating at specific conditions while irradiated sequentially by UV LED than a NIR pulsed laser. The resulting 'green' graphene oxide (gGO) has unique properties, possessing highly oxidized edges with large intact sp2 domains which gives rise to exceptional electrical and optical properties, including purple to deep blue emission of narrow full width at half maximum (<35 nm). Colloidally stable gGO exhibits cytotoxicity owing to the oxidised surface groups while solid-state films of gGO are biocompatible. The continuous flow method of generating gGO also provides unprecedented control of the level of oxidation and its location in the exfoliated graphene sheets by harnessing the high shear topological fluid flows in the liquid, and varying the wavelength, power and pulse frequency of the light source.
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Background and aims: The purpose of this study was to evaluate the bleaching efficiency of two different lasers (KTP and diode 810 nm) on teeth, randomly divided by means an Excel function (Microsoft Excel 2010 "Fx causale") and stored in physiological solution, that were previously stained with different substances commonly considered as a cause of tooth discoloration, such as coffee, tea and red fruits and to investigate the role of laser irradiation in an experimental model, during the dental bleaching process. Methods: Three groups of 45 bovine teeth were created and immersed for one week in a solution of tea, coffee or red fruits respectively. Each group was divided into three sub-groups of fifteen teeth. One was bleached with a 30% hydrogen peroxide gel for 30 min only as control, another 15 teeth group was bleached with the gel plus 810 nm diode laser irradiation and the last group was bleached with the gel plus KTP irradiation. The lasers were applied in three cycles of 30 sec each with a power of 1.5 W localized on a 10 mm spot on the teeth. The temperature of the gel was checked during the bleaching procedure using a thermometer and the colour of each tooth was measured by a spectrophotometer. Results: Statistical analysis of the collected data was performed using Graph Pad Prism, version 6.01 software, Kruskal-Wallis test and Dunn's multiple comparison test and Mann-Whitney test. P value <0.0001 was considered extremely significant (***), P value between 0.001 to 0.01 very significant (**), P value between 0.01 to 0.05 significant (*) and P value >0.05 not significant (ns). By these tests diode laser was effective only at bleaching teeth stained with coffee meanwhile the KTP laser was efficient at bleaching teeth with coffee, tea and red fruits stains. Conclusion: This study suggests that a relation between the laser wavelength and the type of staining on the dental enamel and the efficacy of the whitening treatment exists.
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To comparatively and prospectively compare in a randomized clinical trial, dentin hypersensitivity after treatment with three in-office bleaching systems, based on hydrogen peroxide at different concentrations, with and without light source activation. 88 individuals were included according to inclusion and exclusion criteria. Subjects were randomly divided into the following three treatment groups: Group 1 was treated with three 15-minute applications of hydrogen peroxide at 15% with titanium dioxide (Lase Peroxide Lite) that was light-activated (Light Plus Whitening Lase) with five cycles of 1 minute and 30 seconds each cycle, giving a total treatment time of 45 minutes; Group 2 was treated with three 10-minute applications of hydrogen peroxide at 35% (Lase Peroxide Sensy), activated by light (LPWL) same activation cycles than Group 1, with a total treatment time of 30 minutes; Group 3 was treated with only one application for 45 minutes of hydrogen peroxide at 35% (Whitegold Office) without light activation. Each subject underwent one session of bleaching on the anterior teeth according to the manufacturers' instructions. Dentin sensitivity was recorded with a visual analogue scale (VAS) at baseline, immediately after, and at 7 and 30 days after treatment using a stimulus of an evaporative blowing triple syringe for 3 seconds on the upper central incisors from a distance of 1 cm. A Kruskal-Wallis test followed by Mann-Whitney test was performed for statistical analysis. All groups showed increased sensitivity immediately after treatment. Group 1 displayed less changes relative to baseline with no significant differences (P = 0.104). At 7 and 30 days after treatment, a comparison of VAS values indicated no significant differences between all groups (P = 0.598 and 0.489, respectively).
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Unlabelled: Examining three bleaching systems, this in vivo clinical trial evaluated the relationship among tooth sensitivity, light activation, and agent concentration, and it correlated dental sensitivity with tooth thickness. Materials and methods: Eighty-seven volunteer patients were included. Inclusion criteria were the presence of anterior teeth without restorations as well as the absence of a previous bleaching experience and absence of noncarious cervical lesions or dental pain. Exclusion criteria included pregnancy or breastfeeding, a maximum of TF3 hypoplasia, tetracycline-fluorosis stains, malpositioned teeth, orthodontic treatment, periodontal disease, and/or analgesic/anti-inflammatory intake. Patients were randomly assigned to three bleaching groups: Group A (n=25) was treated with 15% H2O2 and nitrogenous-titanium-dioxide and was light activated (Lase Peroxide Lite, DMC, SaoCarlos, Sao Paulo, Brazil); Group B (n=27) was treated with 35% H2O2 and was light activated (Lase Peroxide Sensy, DMC); and Group C (n=35) was treated with 35% H2O2 (White Gold Office, Dentsply, 38West Clark Ave., Milford, USA) without light activation. Tooth sensitivity (TS) was self-reported by the patients using the visual analog scale (VAS) at baseline (TS0), immediately after treatment (TSI), and at seven days after treatment (TS7). In 46 patients, tooth thickness was determined by computed tomography. TS0, TSI, and TS7 were compared between the A and B groups to determine the effect of concentration and between the B and C groups to determine the effect of light using analysis of covariance. The correlation between tooth thickness and TSI was determined by Spearman Rho test (SPSS 15). Results: Eighty-seven patients were evaluated at baseline, and 61 were evaluated at seven days. Separated by groups, tooth sensitivity, expressed as VAS value at the time points TS0, TSI, and TS7, respectively, were as follows: Group A: 13.76 ± 13.53, 24.40 ± 25.24, and 5.94 ± 5.5; Group B: 15.07 ± 18.14, 42.4 ± 31.78, and 8.68 ± 17.99; and Group C: 10.80 ± 14.83, 31.51 ± 29.34, and 7.24 ± 9.2. Group A showed significantly lower tooth sensitivity than group B at TSI (p=0.032). No differences were observed in the tooth sensitivities between groups B and C. No correlation was encountered between tooth thickness and tooth sensitivity immediately after treatment (Rho=-0.088, p=0.563). The median tooth thickness was 2.78 ± 0.21 mm. Conclusions: Increases in the concentration of bleaching agents directly affect tooth sensitivity, and LED/laser activation and tooth thickness are not correlated with tooth sensitivity after dental bleaching.
Purpose: To evaluate the in vitro effects of two bleaching products developed to be used with halogen or argon laser lights. Methods: 20 human embedded third molars were cut into four parts resulting in 75 useful specimens. The specimens were divided at random into five groups and submitted to the traditional power bleaching procedure for enamel. Group C was separated as a control group. Group 37L was exposed to a 37% carbamide peroxide bleaching solution and exposed to 488 nm argon laser radiation. The same solution was used in Group 37H but the bleaching was exposed to a halogen lamp-based unit. The 35% carbamide peroxide was used in Groups 35L and 35H. One was treated as in Group 37L and the other as in Group 37H. The samples were analyzed for Vickers hardness and also by photoreflectance. Results: Group 37L presented more white spectra than Group 37H. However, Groups 35L and 35H showed similar results. Comparing both bleaching products, the 35% carbamide peroxide was more effective as a bleaching agent than the 37% formulation. No significant difference in Vickers hardness was noted between the two bleaching products.
In some well-established laser applications where large spot sizes are used, an array of high-intensity light emitting diodes (LED) emitting at similar wavelength could potentially replace the laser. This situation applies for the photodynamic bleaching of stains in teeth. This study compared the relative efficacy of an array of visible green LED (535 nm ± 15 nm) with a KTP laser in photodynamic bleaching of tetracycline-stained dentine in human tooth roots. After establishing consistent staining in 96 roots using a validated method, the roots were sectioned into 2-3-mm thick horizontal slices that were treated with gels containing rhodamine B (Smartbleach® or Smartbleach® 3LT). Colour changes were tracked up to 1 month after treatment. While both systems were effective in bleaching the tetracycline-stained dentine, KTP laser activation gave greater bleaching efficacy than LED activation, enhancing the action of the gel. Use of the KTP laser would be preferable over an LED system when confronted with tetracycline staining. Use of this photodynamic bleaching method offers valuable means to reduce the severity of tetracycline staining.
SUMMARY The aim of this study was to evaluate the permeability (PE), microhardness (KHN), and mineral change in enamel after LED/laser activated in-office bleaching. For PE, the coronal portion of premolars (n=51) was subjected to bleaching with 35% hydrogen peroxide (Whiteness HP Maxx, FGM Dental Products, Joinville, SC, Brazil). The samples were stained via the histochemical method, which involves a copper sulphate solution and rubeanic acid. The penetration of dye into the enamel was measured. The KHN of enamel was assessed before treatment, immediately after the bleaching treatment, and again after one week. The calcium and phosphorus content were analyzed with a scanning electron microscope with energy-dispersive X-ray (JSM 6360LV, Jeol Ltd, Tokyo, Japan). The data set from each test was subjected to appropriate parametric statistical analysis (α=0.05). No significant differences were observed for PE in NLA and LA compared to the control group (p=0.98), as well as for calcium (p=0.16) and phosphorus (p=0.80) content. Significant reduction of KHN after bleaching occurred for both groups (p<0.001). After immersion in artificial saliva, the KHN of the enamel for all groups was similar to that seen before bleaching. Light activation during in-office bleaching does not produce significant changes in the enamel compared to a non-light-activated technique.
The aim of this study was to evaluate the increase in temperature induced by various light sources during in-office bleaching treatment, under simulated blood microcirculation in pulp conditions. Ten freshly extracted human maxillary central incisors were used for the study. The roots of the teeth were removed from approximately 2 mm below the cementoenamel junction and fixed on an apparatus for the simulation of blood microcirculation in pulp. A J-type thermocouple wire was inserted into the pulp chamber through an artificial access at the lingual surfaces of the teeth, and another thermocouple wire was fixed on the labial surface of the teeth meanwhile. An in-office bleaching agent, intense red in color and with 30 % water content, was applied to the labial surfaces of the teeth, and repeating measurements were made for each tooth using three different light sources: Er:YAG laser (40 mJ, 10 Hz, 20 s), 810-nm diode laser (4 W, 20 s, CW), and high-intensity light-emitting diodes (LED) (1,100 mW/cm(2), 20 s) as the control. Temperature increase in the pulp chamber and within the bleaching gel during light application were recorded and statistically evaluated. The highest pulp temperature increases were recorded for the diode laser group (2.61 °C), followed by the Er:YAG laser (1.86 °C) and LED (1.02 °C) groups (p < 0.05; analysis of variance (ANOVA), Tukey's honestly significant difference (HSD)). Contradictorily, the lowest gel temperature increases were recorded for diode laser (6.21 °C) and followed by LED (12.38 °C) and Er:YAG (20.11 °C) groups (p < 0.05; ANOVA, Tukey's HSD). Despite the significant differences among the groups, the temperature increases recorded for all groups were below the critical value of 5.6 °C that can cause irreversible harmful changes in pulp tissue. It can be concluded that, with regard to temperature increase, all the light sources evaluated in this study can be used safely for in-office bleaching treatment within the described parameters.
The purpose of this study was to evaluate the surface and intrapulpal temperatures after treatments with different bleaching gels subjected to different types of light activation. A K-type thermocouple and infrared thermometer were used to measure the temperature increase during the 15- or 30-min treatment period. Light-emitting diode with a center wavelength of 405 nm (LED405), organic light-emitting diode (OLED), and femtosecond laser were tested and compared to ZOOM2. The tooth surface was treated with five bleaching agents and Vaseline which served as a control.The generalized estimating equation (GEE) model was applied for testing the differences in temperature increase. The ZOOM2 light source led to the largest increase in mean pulpal and tooth surface temperatures of 21.1 and 22.8 °C, followed by focused femtosecond laser which increased the pulpal and surface temperatures by up to 15.7 and 16.8 °C. Treatments with unfocused femtosecond laser, LED405, and OLED induced significantly lower mean temperature increases (p < 0.001 for each comparison with ZOOM2 and focused femtosecond laser), both in the pulp chamber (up to 2.7, 2.5, and 1.4 °C) and at the tooth surface (up to 3.2, 3.4, and 1.8 °C). Significant differences between pulp chamber and tooth surface measurements were obtained for all types of bleaching gel, during treatments with ZOOM2 (p < 0.001), LED405 (p < 0.001), and unfocused (p < 0.001) and focused femtosecond laser (p ≤ 0.002). Different bleaching agents or Vaseline can serve as an isolating layer. Focused femtosecond laser and ZOOM2 produced large temperature increases in the pulp chamber and at the tooth surface. Caution is advised when using these types of light activation, while LED405, OLED, and unfocused femtosecond laser could be safely used.