Walsh, Laurence J.

University of Queensland eSpace

46 Australasian Dental Practice July/August 2008
the cutting | EDGE
A number of beauty salons and spas now adver-tise “tooth whitening” or “dental bleaching”services to their clients, and, in some cases,
claim equivalence in terms of effect to procedures
undertaken in dental practice. This article addresses
a number of concerns about this trend, and provides
specific comments on claims which are commonly
made by beauty salons.
Does it work: The wrong diagnosis?
Reaching an accurate diagnosis of the cause of
dental discolouration requires expert input from a
dental professional, since only dentists are trained
to diagnose the various forms of discolouration,
and to select an appropriate treatment from range
of available options. Traditional products based on
carbamide or hydrogen peroxide, or related com-
pounds such as chlorine dioxide, may be quite
ineffective against some types of internal dis-
colouration where the coloured molecules are not
susceptible to oxidation. A dentist can advise
whether the problem can be managed by various
professional lightening or whitening treatments, or
whether more extensive cosmetic procedures (such
as veneers or crowns) are needed.
Unless external stains are removed by dental pro-
phylaxis, a proper assessment of the nature and
pattern of staining cannot be made. Moreover, the
presence of surface deposits will impair the penetra-
tion of radicals into the enamel, and surface residues
of saliva and pellicle will neutralize some of the
applied bleaching agent, converting it into harmless
oxygen and water, which will not contribute to a
bleaching action. This is an important point in light
of statements such as these systems “use the same
technology as is used in dental offices for power
whitening, and the results are comparable. The pro-
cedure has been simplified such that trained
aesthetic professionals can now safely perform the
whitening procedure”. The “simplification”
referred to is the removal of the necessary initial
prophylaxis step, and the required protective isola-
tion steps for the gingival and oral soft tissues, thus
compromising both safety and effectiveness, even if
a comparable light and gel were to be used.
The abject lack of knowledge of the manufac-
turers and suppliers of these systems is witnessed in
the form of claims such as “whitening guaranteed”
and by statements such as “whitens teeth stained by
tetracycline, speckled by fluoride, or hereditary dis-
colouration”. There is no system which can treat all
possible types of intrinsic discolouration. Some
types of severe internal discolouration caused by
iron compounds can only be treated by a restorative
approach. Some patterns of tooth shade change such
as fluorosis cannot be removed by bleaching, and
are best treated using other strategies such as
Recaldent, which can return tooth enamel to its
normal colour. It would be completely inappropriate
to undertake bleaching in such cases.
The use of the term “guarantee” raises three
additional significant problems. Firstly, merely by
allowing the teeth to dehydrate, a virtual “whitening
effect” is gained as some of the tooth’s water con-
tent is lost. This effect is readily reversed as the
tooth re-hydrates and is not a true change in the
shade of teeth. Secondly, aging-related changes,
such as dentine sclerosis, mean that vital teeth will
Dental bleaching and beauty 
salons - a case of “little white lies”?
By Professor Laurence J. Walsh
“Promotional
materials for
products used 
in beauty salons
do not have to
pass the TGA
requirements 
for therapeutic
claims... This
unusual situation
has been
exploited 
by some 
manufacturers...”
CPD POINTS AVAILABLE
Continuing Education credits are 
available on this article for subscribers
by answering the questionnaire at
www.dentalpractice.com.au
July/August 2008 Australasian Dental Practice 47
the cutting | EDGE
continue to increase in yellow saturation
with increasing age, even though this pro-
cess may be interrupted, or slowed, by
tooth whitening procedures. It is not pos-
sible (or wise) to guarantee that a change
created by dental bleaching will persist for
a certain period of time. Finally, patients
may have unrealistic expectations as to the
effect that can be achieved by bleaching,
and in particular may have pre-conceived
notions regarding the colour of teeth and
the level of whiteness in teeth, that by
bleaching alone are impossible to achieve.
Is it safe?
Dental bleaching of both external and
internal forms of discolouration employs
reactive oxygen species (ROS), particularly
the hydroxyl and other radicals which pen-
etrate readily through tooth structure. This
inherent reactivity, which causes the
bleaching action, explains why effective
bleaching gels must also be able to cause
tissue irritation and chemical burns when in
contact with gingival tissue, oral mucosa,
skin or eyes. Chemically speaking, there is
no pathway by which one can have an
effective penetrating bleaching action and
an absence of safety issues.
The typical concentrations used when
dentists undertake in-office bleaching
involve the higher concentrations of
hydrogen peroxide, typically 30% and
above. Chemical accelerator systems are
typically employed, e.g. by raising the pH
or by introducing metallic ions or ozone,
to facilitate its breakdown. This may, or
may not, be supplemented with a source
of intense light to facilitate the breakdown
of the hydrogen peroxide into various rad-
icals. When hydrogen peroxide is used in
an in-office setting, protective materials
such as flowable composite resin are
applied to the gingiva and exposed root
surfaces to protect them from direct con-
tact with bleaching gel. In addition,
retractors and suction are used to prevent
inadvertent contact of bleaching gel with
the lips or other soft tissues.
Some beauty salon bleaching treatments
employ hydrogen peroxide products at
concentrations up to 6%. This is above the
nominal risk threshold concentration of
5% (as defined by WorkSafe Australia),
meaning that safe working procedures are
required and duty of care requirements of
workplace health and safety legislation are
invoked. The hazard rating for 3% prepa-
rations is “slight” whereas above 5%, the
preparation is defined legally as a “haz-
ardous substance”. This is an essential
point since it carries a clear obligation for
the user of the product to be cognizant of
the hazards of the product (via a risk
assessment) and to implement effective
control measures to address the hazard.
There are number of published case
reports on chemical burns to the oral soft
tissues from hydrogen peroxide, which
describe blistering of mucosal tissues and
burns of oral and oropharyngeal tissues.1-10
The situation in dental bleaching where the
contact time is prolonged is particularly
Figure 1. Dehydration alone can transiently affect tooth shade. The maxillary teeth
were bleached and moved from shade A2 (before image, on the left side) to shade A1
(after image, on the right side). Note that the lower teeth which were completely
untreated became progressively dehydrated during the bleaching appointment and
their shade has “lightened”. The right panel has been mirror imaged so that the same
teeth are present on both sides of the figure.
Figure 2. The white areas on the gingivae are caused by the irritant effect of radicals
from the bleaching gel that have leaked onto the tissues during the procedure.
48 Australasian Dental Practice July/August 2008
the cutting | EDGE
relevant, since adult patients will sustain
tissue injury in the form of ulcerations
from 30 minutes of contact with 3%
hydrogen peroxide.2 In some beauty salons,
gel is applied for some 60 minutes in a
standard treatment, and no flowable pro-
tective agent is applied to the tissues. There
is thus more than sufficient concentration
and time for chemical injury to occur.
Patients may not necessarily experience
burning sensations when their soft tissues
are contacted accidentally by bleaching
gels - even though significant chemical
injury may have occurred. This damage -
in the form of tissue blanching and ulcer-
ation - may only be noted subsequently in
the gingival tissues at the cervical area, or
on the lips or other mucosae (such as in
the upper airway and pharynx), as a dis-
tinct white change in the tissue with
associated underlying erythema (redness).
Thus, areas of blanching and whiteness on
the gingival tissues which occur with
bleaching products, regardless of whether
they are used dental professionals or
beauticians, represent chemical injury to
the soft tissues.1
If such chemical burns occur, immediate
application of an appropriate radical scav-
enger (such as Vitamin E) is the required
immediate treatment to neutralize oxygen
free radicals that remain, and provided this
is done, the affected areas of tissue should
revert to their normal appearance within
15 minutes. If nothing is done, or the
incorrect antidote is applied (such as
sodium bicarbonate or calcium gluconate),
the chemical burn will result in irreversible
tissue damage. The chemical safety
aspects of hydrogen peroxide are
addressed in detail in the literature [See
reference 1 for a relevant review].
A cold light?
Some beauty salons claim to use the same
“cold-light power whitening technology
seen in professional dental offices”, but
which has been “specially adapted for the
cosmetic beauty industry”. The actual light
sources used are halogen, metal halide and
LED lights, which are essentially no dif-
ferent in design from those used in
dentistry. When intense light sources are
used, the absorption of light energy into the
structure of the teeth, as well as into the gin-
giva, is a major concern. From the
standpoint of physics, there is no form of
intense light which is “cold” when applied
in a dental setting. Even when filters are
used, conventional halogen light sources
and LEDs have been shown to contribute to
a level of thermal change in teeth. In other
words, the issue of heat stress to the teeth is
relevant to all bleaching systems which use
intense light, not only to those used in a
dental practice. There is no inherently
“safe” light source. Rather, the spectral
range of the light source employed is crit-
ical, since certain short wavelengths absorb
strongly in enamel and may also cause ery-
thema (sunburn) as well as photosensitizing
reactions with particular medications such
as calcium channel blockers.
Broad spectrum light sources are now
being used in some beauty salons, including
units which emit in the shorter wavelength
(ultraviolet) ranges. Several additional risks
exist for such systems. The first of these is
photosensitization, the process whereby a
medication which is present within tissue is
activated electronically by particular wave-
lengths of light, resulting in the formation
of oral or peri-oral lesions depending on the
distribution of the intense light which has
been used. Such reactions are more com-
monly associated with the energetic
short-wavelengths of light, i.e. those in the
ultraviolet region. Photo-eruptive lesions
within the oral cavity and peri-oral light-
induced dermatoses have been recognized
as side-effects with a number of medica-
tions, some of which are used relatively
common, such as calcium channel-blockers
for hypertension. Whitening systems which
have light sources that operate in this range
provide specific information regarding
medications which would exclude the
patient from having exposure to these forms
of light.
The second risk with UV systems is
that short wavelength light in the ultravi-
olet spectrum can cause a sunburn-type
response in the oral tissues, with associ-
ated erythema and the release of
prostaglandins. If short wavelength light
sources are used, extreme care must be
taken to provide photo protection of the
oral and peri-oral tissues.
Some beauty salons claim that their
broad spectrum lights use “advanced filtra-
tion systems” that eliminates exposure to
harmful UV light and to heat, yet there is no
objective analysis of the spectral emissions
of these lights to support such a claim.
Terms such as “a safe, filtered blue light to
accelerate the teeth whitening process” are
unsupported by objective peer-reviewed
published data in the literature.
Advertising claims
Promotional materials for products used
in beauty salons do not have to pass the
TGA requirements for therapeutic claims,
since most peroxide products are classi-
fied at the present time as “cosmetics”
Table 1. Professional dental bleaching 
compared with beauty salon treatments
Parameter Dental practice Beauty salon
Operator Dental professional Beautician
Initial contact Part of overall care Opportunistic
Complete Diagnosis Yes No
Range of treatment options Yes No
Range of suppliers and systems Yes No (franchise)
Medical History Routine Variable
Initial Prophylaxis Routine Nil
Gingival protection Routine Nil or variable
Soft tissue isolation Routine Variable
Suction Routine Nil
Materials used High potency Low concentration
Light sources Wide selection More limited choice
Objective evidence of efficacy Yes No
Awareness of complications Yes No
Comprehensive follow-up Yes No
50 Australasian Dental Practice July/August 2008
rather than “devices”. This unusual situa-
tion has been exploited by some
manufacturers who claim that their
whitening treatment “offers the best teeth
whitening available”, “produces superior
results to other teeth whitening options”,
or words to that effect, surpassing profes-
sional in-office treatments, home gels and
even laser whitening. A search of the pub-
lished literature will quickly reveal that
these statements come from an “evidence-
free” zone in that there are no
peer-reviewed clinical studies indicating
such benefits. This is remarkable, given
that there is an immense literature on the
various professional dental bleaching
treatments, and on non-professional prod-
ucts such as paint-on products, whitening
strips and enhanced stain removal tooth-
pastes used at the consumer level.
In summary, the profession’s adoption
of evidence-based practice and the dental
industry’s significant investment in
quality objective research has established
professional whitening treatments (from
professionally supplied gels through to in-
office treatment) as an effective and safe
mode of treatment. Moreover, such treat-
ments are undertaken after establishing a
proper diagnosis, and in the context of a
range of other treatment options (such as
veneers and crowns for more difficult
cases). These and other differences (Table
1) between the two approaches are
obvious when the facts are considered, as
opposed to marketing hype.
Disclaimer
These statements are the personal opinion
of the author and do not represent the offi-
cial view of the various professional
associations, dental boards and universi-
ties with which I am involved. The
statements attributed to advertising mate-
rial for bleaching systems used in beauty
salons are direct quotes taken from cur-
rent (July 2008) websites.
References 
1. Walsh LJ. Safety aspects of hydrogen peroxide used
in dentistry. Aust Dent J 2000; 45:257-69.
2. Shetty K. Hydrogen peroxide burn of the oral
mucosa. Ann Pharmacother. 2006;40(2):351.
3. Fantasia JE, Damm DD. White mucosa. Chemical
burn. Gen Dent. 2001;49(3):265, 324. 
4. Flaitz CM. Chemical burn of the labial mucosa and
gingiva. Am J Dent. 2001;14(4):259-60. 
5. Asanza G, Menchén PL, Castellote JI, Salcedo M,
Jaime B, Senent C, Castellanos D, Cos E. Hydrogen
peroxide-induced lesions in the digestive tract. Report
of 4 cases. Rev Esp Enferm Dig. 1995;87(6):465-8.
6. Laskaris G. Color Atlas of Oral Diseases, 2003.
page 70.
7. Watt BE, Proudfoot AT, Vale JA. Hydrogen per-
oxide poisoning. Toxicol Rev. 2004;23(1):51-7.
8. Dickson KF, Caravati EM. Hydrogen peroxide
exposure - 325 exposures reported to a regional poison
control center. J Toxicol Clin Toxicol.
1994;32(6):705-14. 
9. Rotstein I, Wesselink PR, Bab I. Catalase protection
against hydrogen peroxide-induced injury in rat oral
mucosa. Oral Surg Oral Med Oral Pathol. 1993
Jun;75(6):744-50.
10. Henry MC, Wheeler J, Mofenson HC, Caraccio
TR, Marsh M, Comer GM, Singer AJ. Hydrogen per-
oxide 3% exposures. J Toxicol Clin Toxicol.
1996;34(3):323-7. 
About the author
Professor Laurence J. Walsh is the tech-
nology editor of Australasian Dental
Practice magazine. He is also a noted
commentator on and user of new technolo-
gies and is the Head of The University of
Queensland School of Dentistry.
the cutting | EDGE


Dental bleaching and beauty salons - a case of "little white lies"

http://espace.library.uq.edu.au/view/UQ:159914/Bleaching.pdf

Dental bleaching and beauty salons - a case of "little white lies"

Abstract

Similar works

Full text

Available Versions

University of Queensland eSpace