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Teeth Whitening
Home Study Course #5030 - 3 Credits
This activity has been planned and implemented in accordance with the standards
of the Academy of General Dentistry Program Approval for Continuing Education
(PACE) through the joint program provider approval of Dynamic Dental Educators
and Swank HealthCare. Dynamic Dental Educators is approved for awarding
FAGD/MAGD credit. Approval does not imply acceptance by a state or provincial
board of dentistry or AGD endorsement, 11/01/2013 to 10/31/2017, Provider ID
#300115.
Florida Board of Dentistry Approved Provider #50-557. Dental Board of California
Registered Provider #3964.
This continuing education activity has been planned and implemented in accordance with
the standards of the ADA Continuing Education Recognition Program (ADA CERP)
through joint efforts between Dynamic Dental Educators and Swank HealthCare.
Dynamic Dental Educators is an ADA CERP Recognized Provider. ADA CERP is a service
of the American Dental Association to assist dental professionals in identifying quality
providers of continuing dental education. ADA CERP does not approve or endorse
individual courses or instructors, nor does it imply acceptance of credit hours by boards of
dentistry. Concerns or complaints about a CE provider may be directed to the provider or
to ADA CERP at www.ada.org/goto/cerp. Review date: 5/01/2014. Expiration date:
5/01/2017.
This home study continuing education course is only meant for relicensing purposes.
Limited information is provided as an overview of the subject matter and potential risks
exist when attempting to incorporate techniques or procedures using limited knowledge and
without supervised clinical experience. This course is not intended to be a comprehensive
or authoritative source.
For questions, please contact
Swank HealthCare Customer Service:
Phone: 800.950.4248 Email: [email protected]
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Copyright 2003 Dynamic Dental Educators. All Rights Reserved.
No portion of this text may be copied, reproduced or used in any way without the written
permission of Dynamic Dental Educators.
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Table of Contents
Objectives ................................................................................................... 2
Introduction ................................................................................................. 3
History......................................................................................................... 4
Biological Aspects ...................................................................................... 4
Extrinsic Stains ........................................................................................... 5
Intrinsic Stains ............................................................................................ 5
Non-Vital (Internal) Tooth Bleaching ........................................................ 6
Vital (External) Tooth Bleaching................................................................ 7
Bleaching Relapse ....................................................................................... 9
Comparing Bleaching Strips, Hydrogen Peroxide and Pre-Brushing........ 9
Safety Concerns ........................................................................................ 11
Other Teeth Whitening Options ................................................................ 14
Conclusion ................................................................................................ 16
References ................................................................................................. 17
Dynamic Dental Educators – Teeth Whitening
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Objectives
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Review tooth discoloration types.
•
Learn the history of teeth whitening.
•
Know the most commonly used bleaching methods and techniques.
•
Know what chemicals are used for bleaching and the concentration levels.
•
Determine between intrinsic and extrinsic stains.
•
Know aesthetic effects and adverse reactions to internal bleaching procedures.
•
Recognize general results and side effects of external bleaching.
•
Be aware of the dangers of hydrogen peroxide ingestion.
•
Understand the options for non-bleaching, smile enhancement.
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Introduction
Tooth bleaching is a popular cosmetic procedure that can give someone a brighter smile and the
appearance of youth by reducing discoloration on stained teeth. These stains occur due to the
consumption of certain foods, drinks, and the use of certain medications. Discoloration may also
results from traumatic injury or pulpal death.
There are a variety of bleaching techniques which include: in-office procedures and home
treatments. The results of both are generally successful, although a common side effect is an
increase in tooth sensitivity. This generally resolves within a few weeks after treatment is
discontinued. The sensitivity side-effect can be reduced by pre-treating with calcium, fluoride
preparations, or both. For patients who are not good candidates for bleaching, other alternatives
exist for whitening a smile, such as bonding, veneers, and microabrasion.
As demand for in-office external teeth whitening grows, so does the demand for less costly
customer-directed programs. These include professionally-dispensed custom-tray-based systems
and over-the-counter (OTC) systems. The latest tooth whitening trend is the availability of
whitening treatments or kits in non-dental retail settings, such as mall kiosks, salons, spas and
more recently, aboard passenger cruise ships.
Tooth discoloration varies in etiology, appearance, severity, location, and degree of integration
with the tooth structure itself. Discoloration may be either intrinsic (within the tooth structure)
or extrinsic (external to the tooth itself), or a combination of both. Improvement is measured in
terms of shade by using either the Vita Shade Guide (4 shade ranges (A-D) with 4 to 5 darkness
levels within each shade range) or the L*a*b* system which measures the change in lightness
(L*, which should increase) and yellowness (b*, which should decrease) from pretreatment to
post treatment (American Dental Association (ADA), 2006).
Analysis of the various methodologies has raised questions about the efficacy of different
programs, and ways to maximize bleaching effectiveness while minimizing short and long-term
side effects. Non-dental whitening venues have come under scrutiny in several states and
jurisdictions, resulting in actions to reserve the delivery of this service to dentists or
appropriately supervised allied dental personnel.
The role of the professional in this process cannot be underestimated as the source of staining,
potential bleaching effectiveness, sensitivity, along with the soundness of the teeth, and overall
oral health all impact bleaching outcomes. Some of these are things only a professional may be
able to evaluate, so a partnership between the patient and dental practitioner is highly
recommended. The ADA advises patients to consult with their dentists to determine the most
appropriate treatment.
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History
In 1864, James Truman described a bleaching process for discolored, pulpless teeth. Since then,
chloride, sodium hypochlorite, sodium perborate, and hydrogen peroxide have been used
variably; alone, in combination, and sometimes with thermo-catalytic activation, to boost the
effects of the treatment.
A walking bleach technique introduced in 1961, initially involved pulp chamber placement of
sodium perborate and water. The pulp chamber was sealed off for a period of time during this
technique. In a later modification, the water component was replaced by 30% to 35% hydrogen
peroxide, to accelerate the whitening effect.
In the late 1960s, an orthodontist who had prescribed an antiseptic tray with 10% carbamide
peroxide for a patient’s gingivitis discovered the chemical caused lightening of the teeth. This
marked the beginning of the night guard bleaching era, but the method was not described in
professional dental literature until over 20 years later.
Biological Aspects
Tooth scaling and polishing removes many extrinsic stains. Usually this is an in-office procedure,
but the patient may use an abrasive toothpaste to effect some of the same results. Some extrinsic
discoloration and intrinsic stains need to be resolved by the use of dental bleaching.
There are two in-office, tooth-bleaching options. The first is non-vital tooth bleaching, also
known as intracoronal bleaching. This is an alternative for pulpless teeth involving internal
treatment and requiring knowledgeable, professional administration. The second is vital tooth
bleaching which may be handled completely by the dental practitioner, or in combination with
at-home treatments. Both are generically referred to as chairside bleaching, since they are
professionally administered for best results.
Present tooth bleaching techniques are based upon hydrogen peroxide as the active agent,
although 10% carbamide peroxide is also used in professionally dispensed products. The
bleaching agent is applied directly, or produced in a chemical reaction from sodium perborate or
carbamide peroxide. Hydrogen peroxide forms free radicals, reactive oxygen molecules, and
hydrogen peroxide anions. These react with the long-chained, dark-colored chromophore
molecules that are responsible for the stain. Bleaching success depends on bleaching agent
concentration, ability to reach the stain, and contact duration and frequency.
A good candidate for teeth whitening is someone who has teeth which have yellowed over the
years due to aging. If a patient can remember their teeth being whiter when they were young,
there is a very good chance bleaching will whiten them again. Bleaching works best on age
related discolorations. The front teeth should be healthy with no cracks or decay and evenly
colored with no bands of color or bonded or restored areas.
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If a patient has dental work, they may need to have it replaced to match the new color of their
teeth after the whitening procedure is complete.
If a patient’s teeth reveal a gray or brown color, bands of different color or have always looked
dull, they may have internal staining and not be an ideal candidate for bleaching. This type of
staining does not respond well to bleaching and satisfactory results may not be achieved. Teeth
with crowns or multiple fillings do not respond to whitening products, therefore are also not
good candidates for bleaching.
If a patient is not a good candidate for bleaching, their alternatives for whitening may be either
bonding or veneers.
Extrinsic Stains
Extrinsic stains are on the external surface of the tooth, or in the plaque or calculus and are often
mechanically removed. A good cleaning, which includes; polishing and tooth scaling, and
improved patient oral hygiene, can make a dramatic difference.
Over time, some extrinsic stains can become intrinsic. This is usually seen in tobacco users and
in those with restorative dental work.
Some causes of extrinsic discoloration are:
•
•
•
•
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Foods and tobacco, coffee, tea, red wine, oranges, tobacco, dark soda and juice, brightly
colored foods such as grapes, blueberries and tomato sauce
Wear of the tooth structure
Deposition of secondary dentin (aging)
Pulp inflammation
Dentin sclerosis.
Intrinsic Stains
Intrinsic stains are internal to the tooth and may affect one or more teeth. Exposure to various
medicines such as tetracycline or chemicals such as fluoride during tooth formation can cause
visible bands of staining. Other culprits resulting in discoloration are: congenital defects in the
dentin or enamel, pulp death, dentin damage, and the aging process. The severity of stains is
dependent on the causative agent and the amount of exposure.
Some causes of pre-eruptive intrinsic discoloration are:
•
•
•
•
Exposure to high fluoride levels
Tetracycline exposure can cause gray discoloration
Congenital development disorders
Trauma.
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Some causes of post-eruptive intrinsic discoloration are:
•
•
•
Aging
Pulp necrosis (death)
Complications of a medical treatment.
Teeth discoloration can also be caused when a tooth has been broken or chipped, as well as by
silver fillings and root canal fillings.
Non-Vital (Internal) Tooth Bleaching
Intracoronal tooth bleaching is a conservative alternative to more invasive endodonic treatments
of non-vital, pulpless, discolored teeth. Careful examination is necessary, since the method
requires healthy periodontal tissues and a root canal that is properly obturated to prevent the
bleaching agent from reaching the periapical tissues.
A walking bleach procedure using sodium perborate and water or hydrogen peroxide and is
placed in the pulp chamber, sealed inside, and replaced every 3 to 7 days until the desired level
of bleaching is achieved. If the tooth has not responded satisfactorily after 2 to 3 treatments, the
technique can be supplemented with an in-office bleaching procedure. The three solutions
typically applied; sodium perborate in 30% hydrogen peroxide, sodium perborate in 3%
hydrogen peroxide, and sodium perborate in water, seem to be equally effective in bleaching
non-vital teeth. There are also current techniques for intracoronal bleaching of stained, root-filled
teeth employing oxidative bleaching with hydrogen peroxide.
A variation of the walking bleach technique reduces patient chair time. The coronal replacement
and coronal part of the root filling are removed to access the pulp chamber. The remaining root
filling is sealed off with glass-ionomer cement. The patient periodically places new bleaching
agent, usually 10% carbamide peroxide, in the pulp chamber, and seals the lingual aspect of the
tooth with a plastic splint. The chamber is left unsealed during the weeks of treatment. The
patient’s ability to do this safely is questionable; the risk of leakage and the potential for serious
adverse reactions should not be a tradeoff for patient convenience.
Other variations on techniques for intracoronal bleaching utilize a thermo-catalytic method;
heating a pellet soaked with 35% hydrogen peroxide, and bleaching with 10% carbamide
peroxide. These have high quality and long term aesthetic and biological results, but durability of
the result is variable.
The inside/outside bleaching technique, which uses 10% carbamide peroxide in trays, is an
effective and safe method of bleaching non-vital teeth. Although more than 90% success has
been reported, regression of the color change can be a problem in vital and non-vital tooth
bleaching and retreatment is necessary in many cases, usually after 1 to 3 years.
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Vital (External) Tooth Bleaching
Patients who want to improve the appearance of pulp-filled teeth that are fed by a blood supply
(vital teeth) may choose from different types of delivery systems dispensed in the dental office or
given out for home use.
These methods include:
•
•
•
•
In-office techniques with and without light or heat enhancement
Tray-based (mouthguard) bleaching
Professionally dispensed and OTC whitening strips
Whitening dentrifices.
Professional whitening products and methods will brighten the look of teeth that have dulled due
to intrinsic and extrinsic staining. Vital tooth bleaching utilizes various concentrations of
hydrogen and carbamide peroxide solutions or gels to improve the appearance of teeth so that
patients and dentists can avoid more invasive esthetic procedures.
In-Office ‘One-Hour’ Bleaching
In-office bleaching systems use high concentrations of hydrogen or carbamide peroxides (25% to
35%) in a paint-on bleaching gel or solution that takes effect within an hour to an hour and a half
(“power bleaching”). This is a convenient procedure for patients who cannot find the time to
apply trays or strips in their busy lives, yet can schedule the time for one or more dental
appointments. Clinicians may offer a light or heat-enhanced technique such as BriteSmile or
Zoom 2 (Discus Dental) or LumaArch (LumiBrite) specifically for bleaching or a laser-activated
bleach such as Sapphire PAC Light (Den-Mat) that is based on a plasma arc high-intensity
photopolymerization and used for in-office whitening and for resin photopolymerization.
In laser teeth whitening, the dental professional applies a whitening gel, the crystals of which are
activated with an argon laser light. The energy in the crystals penetrates tooth enamel and creates
a lightening effect. The degree of discoloration determines the length of treatment time, but
usually one visit is enough to complete the process. Argon laser bleaching is effective for dark
stains as well as deep gray or blue discoloration, but it's even more likely to leave teeth
extremely sensitive, more than power bleaching or night guard kits.
The intraoral use of high concentration peroxide gels requires specific safety protocols. Gingival
soft tissues adjacent to the procedure must have a barrier placed. A manufacturer-provided, lightcured resin is preferable to a dental dam as it is less likely to interfere with the quality of the
results. Eye protection must be worn by both the clinician and patient. The use of lasers for the
purpose of tooth whitening is regulated by the FDA, so manufacturers must submit light systems
for marketing approval.
Tray-Based Delivery
Custom-fitted trays made from casts of patients’ teeth are dependable delivery systems for
whitening treatments performed either in-office or at home. They are filled with the peroxide
containing bleaching agent and depending on the concentration level and choice of dentist-
Dynamic Dental Educators – Teeth Whitening
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assisted or self-administered, are left in place for at least 30 minutes at a time. Chemical
modifications have extended the bleaching potential of carbamide peroxide gels so that the trays
can be worn overnight (Strassler, 2006). By contrast, hydrogen peroxide-based vital tooth
bleaching products deplete half the bleaching potential after 30 minutes.
Higher concentrations of peroxides, both carbamide peroxide and hydrogen peroxide, typically
decrease the wear time of the tray. Depending on the nature of patients’ discoloration, trayless
strip technology (i.e. professionally dispensed whitening strips) could be administered in
conjunction with tray use. Successful at-home bleaching requires a properly trimmed
mouthguard, and detailed instructions for the patient to follow. Although protocol will vary
between patients, most should expect to wear the tray for at least an hour a day to attain up to
90% of the whitening effect.
Professionally Dispensed Whitening Strips and
Over-the-Counter Products
Whitening strips are thin, flexible polyethylene bands applied directly to the facial surface of
anterior teeth (canine to canine). They are available in both professional strength and over-thecounter versions and deliver a measured dose of peroxide agent through the enamel. This
minimizes peroxide dosage and thus decreases tooth sensitivity, while reducing treatment time
and making whitening more convenient. Hydrogen peroxide product concentrations vary from
5% to 14%, while concentrations of carbamide peroxide range from 10% to 32% (Sapphire
Home Whitening).
Patients who have superficial defects will discover a disadvantage in the use of whitening strips.
Teeth which are not perfectly smooth or aligned may cause the strips to make improper contact
with the tooth surface, thus causing uneven results. Trayless systems, such as Opalescence
Trèswhite (Ultradent Products) have been introduced to cover more teeth and whiten effectively,
regardless of tooth alignment. A membrane containing a 10% or 15% peroxide whitening gel is
applied to upper and lower teeth by a disposable plastic tray. The membrane adheres tightly for
30 to 60 minutes and is then discarded.
Another product is a self-administered light activated whitening gel. This system, marketed and
sold direct to the consumer as Ionic White Tooth Whitening system, uses silver ions activated by
a blue led light to cause the bleaching ingredients to work faster and penetrate more deeply.
Treatment is completed in 21 minutes and results are immediate with continued whitening for
several days afterwards. Bleaching effectiveness is based on the severity and cause of stains, and
the length of time the stains have existed. Patient discomfort with this system is reportedly less
than other methods of teeth whitening.
Whitening Dentrifices
Whitening toothpastes may be used for milder staining or post-bleach maintenance. These
contain polishing agents that remove surface stains with an abrasive, such as silica, or provide
chemical chelation. Carbamide peroxide, or sodium tripolyphosphate, can be formulated in low
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concentrations in whitening toothpastes, but it is silica bits, or calcium phosphate which do the
work of removing surface stains. Care has to be taken the toothpaste is not too harsh since it may
cause structural damage to the enamel or to the softer exposed dentin if there is gingival
recession. These dentrifices are not designed to whiten teeth with internal stains. This is best
done by a dental professional using bleaching or other in-office techniques.
Toothpastes with hydrogen peroxide are not very effective because the peroxide reacts with other
substances on the teeth. The effectiveness is also dependent on the duration of time peroxide is
on the teeth. The longer it is in contact with the tooth surface, the better it works. Since brushing
is usually done quickly, peroxide does not have much time to work properly.
Bleaching Relapse
Vital and non-vital tooth bleaching is safe, especially when the process is supervised by a dentist.
Topically applied whitening agents have been noted in many studies to be clinically effective and
long-lasting, yet bleaching relapse has been known to occur. Clinical Research Associates
reported a 41% shade regression after one year of in-office vital tooth bleaching procedures
(Strassler, 2006). The efficacy of at-home tray application is reportedly better, only 25% relapse
after 18 months, according to one study. The original concentration of the peroxide agent seems
to have no effect on the final shade evaluation.
The thermo-catalytic and the conventional walking bleach procedures used for intracoronal
bleaching have each produced over 90% immediate success. But, retreatment may be necessary
depending on the patient’s desired whiteness level and others factors which may restain the teeth.
Need for Retreatment for Patients Treated with Non-Vital Tooth Bleaching
Time Since Treatment
1-2 years
3-5 years
Up to 8 years
3-15 years - Tetracycline stained teeth
Need for Patient
Retreatment (approx)
10%
20% to 25%
40%
20%
Patients can best prevent bleaching relapse and maintain their results by using a whitening
toothpaste and brushing with a power toothbrush. Touch-up treatments might be desirable on a
yearly basis to break up intrinsic stains that may develop.
Comparing Bleaching Strips, Hydrogen Peroxide and Pre-Brushing
In a randomized clinical trial, 36 subjects were divided into 3 groups in order to compare the
efficacy of two different hydrogen peroxide concentrations when pre-brushing with an anticavity toothpaste:
Dynamic Dental Educators – Teeth Whitening
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•
•
•
Pre-brushing with anti-cavity toothpaste, and used a 5.3% hydrogen peroxide strip
Pre-brushing with anti-cavity toothpaste, and used a 6.5% hydrogen peroxide strip
Brushing alone (control).
The results of this study shows pre-brushing with an anti-cavity toothpaste and increasing
hydrogen peroxide from 5.3% to 6.5% in a strip-based delivery system, substantially improves
results with minimal side effects and impact on patient tolerability.
Bleaching Strips, Hydrogen Peroxide Concentration
Delivery Method
Pre-Brushing with anticavity toothpaste.
5.3% Hydrogen
Peroxide Strip
31% improvement
in whitening.
6.5% Hydrogen Peroxide
Strip
60% improvement in
whitening.
Another study looked at using whitening strips (6.5% hydrogen peroxide) along with no brushing
and pre-brushing with an anti-cavity toothpaste before the application of the strips. The results
show that pre-brushing with an anti-cavity toothpaste dramatically increases the whitening
results of the strips.
Bleaching Strips, Pre-Administration Tooth Brushing
Delivery Method
No Brushing
6.5% hydrogen
peroxide strip.
5% improvement in
whitening.
Pre-Brushing with Anti-Cavity
Toothpaste
33% improvement in
whitening.
The overall results of the above two studies show that all groups; no matter which combination
they used, experienced significant whitening, decreased yellowness, and increased brightness,
with improved composite color changes relative to their initial baseline. All treatments were well
tolerated by patients with little or no side effects.
Comparison of Tray Delivery and Strip Delivery
A study was performed with a group of 34 adult volunteers who ranged in age from 20 to 47
years old for a 7 day treatment. The entire group had their baseline color established and where
85% female and 91% nonsmoking. They were split into 2 groups; one group used a tray delivery
system of 5% carbamide peroxide and the other group used 6% hydrogen peroxide whitening
strips.
Both groups experienced statistically significant whitening, although the strip group improved
more dramatically in all measured parameters – yellowness, brightness, composite, and a new
parameter, relative change from baseline.
Digital image analysis assessed color change in yellowness, brightness, and composite after 7
days, while tolerability was assessed through interview and examination. Both treatments yielded
a statistically significant whitening benefit compared to their baseline. The strip group
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experienced greater color improvement on average for all color parameters in the study. No test
subjects discontinued their treatment due to adverse reactions.
Comparison of Carbamide Peroxide Tray-Delivery with Hydrogen Peroxide Strip Delivery
Delivery Method
5% carbamide peroxide with
potassium nitrate in a custom tray,
6-8 hours daily contact.
6% hydrogen peroxide bleaching
strips, 1 hour daily contact.
Results
Yellowness reduced,
tooth sensitivity reported: 22%.
Yellowness reduced close to twice
that of tray system,
tooth sensitivity reported:13%.
Another study compared a tray system using 10% hydrogen peroxide and carbamide peroxide
with 6% hydrogen peroxide strips. The tray system had 28 hours of total contact and the strips
had 21 hours of total contact. Whitening response was measured from digital images of the
maxillary anterior teeth.
Both studies resulted in significant yellowness reduction, brightness increase, and overall color
improvements. At intermediary time points, and at the end of the study, the strip group had
superior whitening response in all parameters measured. Both groups tolerated treatment well
with 35-40% of each group reporting tooth or gum sensitivity. No test subjects had discontinued
their treatment due to sensitivity.
Safety Concerns
Tooth Sensitivity
At least half of all patients who undergo whitening procedures report tooth sensitivity during the
bleaching process. This can occur as the bleaching agent diffuses into the tooth structure, causing
inflammation of the pulp along with dehydration. Symptoms are usually mild and dissipate as the
treatment progresses. Heightened sensitivity is most common when in-office hydrogen peroxide
bleaching is enhanced with heat. Most patients experience complete relief within four days.
Reasons for on-going, post-procedural tooth bleaching are not well understood. Patients with
thinning enamel, large pulps and carious lesions may be at greater risk for post-operative
discomfort. Cold sensitivity and intermittent spontaneous pain has been reported up to 39 days
following treatment. Some enhancements may be necessary to help reduce post treatment
discomfort:
•
•
•
•
•
Extra care for patients with large restorations, cervical erosion, or enamel cracks
Using a milder peroxide formula or gel
Administering a pre-bleaching fluoride or potassium nitrate treatment
Sealing restorations
Pre-procedure medication.
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Mucosal Irritation
Gum irritation is another common side effect of vital and non-vital tooth bleaching. This can
happen when trays are fitted poorly, or because a bleaching gel is in contact with the gingiva for
too long. In high concentrations, i.e. from 30% to 35%, hydrogen peroxide is caustic to mucous
membranes and may cause burns and bleaching of the gingiva, and produce inflammatory
changes. In approximately 10% of custom-made trays of carbamide peroxide, from 25% to 40%
of patients reported gingival irritation.
Using a fluoride gel or potassium nitrate toothpaste just prior to the whitening procedure will
fortify the gums against the bleaching solution. Brushing with a paste or gel, formulated for tooth
sensitivity, for two weeks before whitening treatments begin can also aid in reducing postprocedure sensitivity.
Alteration of Enamel Surface
Enamel tooth surfaces exposed to bleaching agents change over time. Using a 35% carbamide
peroxide solution for 30 minute daily for 14 days destroys the aprismatic enamel layer; the
damage was still present 90 days later. Ten percent and 16% concentrations did not show the
same changes in inorganic enamel concentration. Since bleaching agents can destroy tooth
enamel, bleached teeth may become more vulnerable to future extrinsic discoloration.
Effects on Restorations
Dental amalgams exposed to carbamide peroxide have an increase in mercury release from 4 to
30 times greater than in saline controls. Bleaching may increase glass-ionomer and cement
solubility and temporarily decrease enamel/resin-based bond strength in the first 24 hours after
bleaching. After bleaching, hydrogen peroxide residuals in the enamel inhibit resin-based
material polymerization, which reduces bonding strength. Due to bond strength reduction, toothbleaching agents should not immediately precede resin-based restorative treatments.
General Side Effects
It is essential for the periodontal tissues to be healthy, and for the root canal to be effectively
sealed off from the supporting bone structure to prevent endodontic treatment failure, ingestion
of the bleaching agent, and subsequent dentin staining from food and beverage pigments.
Hydrogen peroxide penetrates enamel and dentin into the pulp chamber and is enhanced by
repeated exposure from additional treatments. Heat further increases dentin permeability. The
presence of cervical defects in the cementum can also assist hydrogen peroxide to penetrate the
dentin. Additionally, these cervical defects are considered to be a risk factor for the thermocatalytic bleaching procedure, since their presence seems to be linked to increased resorption.
Intracoronal bleaching has been linked to tooth crown fractures and reducing the micro-hardness
of dentin and enamel. Non-vital tooth bleaching can result in cervical root resorption, an
inflammatory response, especially when a thermo-catalytic procedure is used. This is more
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common when treated teeth have had previous trauma, but trauma alone does not guarantee
resorption. Some theories on causes of resorption include:
•
An inflammatory response triggered when the bleaching agent reaches periodontal tissue
through the dentinal tubules
•
Peroxide denaturing the dentin through the dentinal tubules, with the external root then
attacked as a foreign body.
Genotoxicity of Hydrogen Peroxide and Carbamide Peroxide
Direct contact of bacteria and cultured cells with hydrogen peroxide and carbamide peroxide
tooth whiteners induces genotoxic effects. However, there is no evidence of DNA damage in
vivo nor in vitro when metabolizing enzymes are present.
Extensive animal studies in mice and hamsters shows hydrogen peroxide to have a weak local
carcinogenic-inducing potential. Genotoxic action is a possibility since free radicals formed by
hydrogen peroxide can attack DNA. Hydrogen peroxide may act as a tumor-promoter, but the
risk is only of concern for patients who already have an increased oral cancer risk due to tobacco
use, alcohol abuse, or genetic predisposition.
Although extensive animal and bacterial studies have suggested that hydrogen peroxide
promotes tumor growth, the effect of limited exposure during the teeth bleaching process is
inconclusive. Some researchers recommend limiting carbamide peroxide exposure to a 10%
concentration or less for teeth bleaching.
Hydrogen Peroxide Ingestion
The acute side effects of hydrogen peroxide ingestion depend on the amount ingested and the
solution concentration. Side effects may include: vomiting, cyanosis, convulsion, respiratory
failure, cerebral infarction, and ischemic heart changes. Oral mucosa, esophagial and stomach
ulcerations; along with nausea, vomiting, abdominal distention, and sore throat are more likely
side effects of hydrogen peroxide ingestion. Because of these side effects, it would not be
prudent to perform dental bleaching on children.
Risk Assessment of Vital Tooth Bleaching
Using the tray process for tooth bleaching, and following the manufacturer’s instructions, at least
25% of the bleaching agent is usually ingested by the patient during a 2 hour bleaching period.
Longer bleaching periods in a given day, multiple applications, simultaneous bleaching of
maxillary and mandibular teeth, and overfilling the tray increase the risk of overexposure
through ingestion.
If both maxillary and mandibular teeth are to be bleached at the same time, the solution
concentration should not exceed 7.9% hydrogen peroxide (or 22% carbamide peroxide). To
ensure patient safety during the tooth bleaching process, preparations of the bleaching agent
Dynamic Dental Educators – Teeth Whitening
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should be done with a low concentration of either hydrogen peroxide or carbamide peroxide.
Overfilling the tray, not removing excess material, biting on the tray, and simultaneous bleaching
of both arches increases the risk of hydrogen peroxide overexposure.
Legal and Ethical Aspects of Cosmetic Whitening
To address the safety of bleaching materials, the American Dental Association (ADA) first
convened a panel of experts in 1993. The ADA subsequently published its first set of guidelines
for evaluating peroxide-containing tooth whiteners. These guidelines have been revised
periodically. Laboratory studies, toxicological studies, and clinical data, are used to evaluate
products used in the tooth bleaching process. If an ingredient has already been proved safe and
effective, laboratory studies are sufficient. Tooth whitening agents are not currently regulated by
the Food and Drug Administration (FDA).
Other Teeth Whitening Options
Bonding, Veneers, and Microabrasion
If tooth enamel is seriously damaged or other factors suggest that bleaching may not give
satisfactory results, bonding can be a reasonable choice. This cosmetic procedure uses tooth
colored materials that are fused to the surface of each tooth. The dentist coats each tooth with a
thin layer of resin which gets its natural looking brightness from finely ground quartz. It is then
contoured to the proper shape and hardened using light or heat. Sometimes the resin is removed,
baked, and cemented back onto the tooth. Bonding can last up to eight years, but resin is prone to
chipping and will stain just as normal teeth stain.
Porcelain veneers are another, more expensive option for badly stained or chipped teeth. They
also improve teeth which are crooked, or eroded at the gum line. The thin, custom made shells
are crafted of tooth colored materials designed to cover the front side of teeth. The dentist etches
each tooth's surface, removing some tooth enamel and then glues on a thin piece of porcelain
with a ceramic or composite resin. Patients get to choose the exact shade of white they want. The
process is not reversible and although the veneers themselves are somewhat stain resistant, they
should be conscientiously cared for to keep their sheen.
In microabrasion, the dentist grinds a thin layer off the surface of the teeth. This method works
best for enamel defects like white or brown spots from fluorosis; a harmless condition which
results from swallowing too much fluoride while teeth are still developing. The surface spots are
removed, revealing a smooth layer of enamel.
Whitening Naturally
External stains on teeth can be whitened naturally, by eating certain foods. This may not return
the teeth to their original brilliance, but it will aid in decreasing discoloration and can prolong
retreatment of future whitening procedures. Even brushing teeth with baking soda twice a month
will help remove some stains and dental plaque buildup.
15
Chemical pigments and naturally occurring tannins stain the teeth, so foods that contain them
should be limited: coffee, dark syrup sodas, dark colored juices, red wine and blueberries. The
use of a straw can assist with stain control. This allows the food dyes to bypass the teeth as the
liquids are consumed.
Some foods which aid in whitening are: apples, pears, strawberries, celery, lemons, carrots,
cauliflower, cucumbers and any other raw vegetables. These foods produce saliva which mix
with the natural fibers of the food to clean teeth and destroy bacteria.
Certain chewing gum product brands suggest they control tarter and whiten teeth by neutralizing
food acids in the mouth. Chewing sugarless gum may indeed help clean teeth surfaces because it
increases saliva production. Patients with Temporo-Mandibular Joint (TMJ) should be cautioned
when chewing gum since the muscles used for chewing may spasm, causing discomfort, pain and
tenderness.
Avoid smoking. Even modest use of tobacco can cause discoloration patterns in the tooth enamel
or dentin, besides negatively impacting one’s overall oral health.
Dynamic Dental Educators – Teeth Whitening
16
Conclusion
Many choices exist for the dental patient to whiten their teeth. The dental professional needs to
educate their patient on the causes of their dental stains and the system or systems best suited to
achieve the results to eliminate or decrease tooth discoloration. Below is a list of whitening
processes available to the consumer:
Product Type
Professionally
supervised and
in-office.
How it Whitens
Veneers, Bonding,
Microabrasion.
How Well it Works
Skilled practitioners can produce
excellent results with these three
methods.
Peroxide in trays or
Highly effective on a range of
directly applied. Light
stains. At least 5 shades
may be used. Immediate
improvement. Probable
results.
sensitivity.
Professionally
Quick working
Effective on many types of
supervised and
professional peroxide
stains, including internal. Up to 6
dispensed
concentration in strips,
shades improvement with long
products.
gels or trays. Results over lasting results. Probable
time.
sensitivity.
OTC limited
Low concentration
Can be effective on age related
use: whitening
peroxide base. General
and slight diet related stains. Up
strips and paint
daytime wear. Paint on
to 2 shades improvement for 6
on products.
for overnight use.
months.
OTC daily use:
Mechanically removes
Effective on slight surface stains
toothbrush,
surface stain. Gum and
only. Up to 2 shades
toothpaste, floss, some toothpaste claim to improvement.
mouth rinse,
coat the teeth to prevent
gum.
staining.
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References
American Dental Association (ADA) - Statement on the Safety and Effectiveness of Tooth
Whitening Products - www.ada.org/1902.aspx
American Dental Association (ADA), ADA Council on Scientific Affairs - Tooth
Whitening/Bleaching: Treatment Considerations for Dentists and Their Patients (revised Nov.
2010) –
www.ada.org/sections/about/pdfs/HOD_whitening_rpt.pdf
American Dental Association (ADA), ADA Council on Scientific Affairs - Dentist Dispensed
Home-Use Tooth Whitening Products www.ada.org/sections/scienceAndResearch/pdfs/guide_home_bleach.pdf
About Cosmetic Dentistry - Choosing the Color of Dental Implants (Vita Shade Guide) www.aboutcosmeticdentistry.com/procedures/dental_implants/implant_color.html
About Cosmetic Dentistry - Cosmetic Dental Procedures – Dental Bonding –
www.aboutcosmeticdentistry.com/procedures/dental_bonding/index.html
About Cosmetic Dentistry - Cosmetic Dental Procedures - Tooth Whitening www.aboutcosmeticdentistry.com/procedures/tooth_whitening.html
About Cosmetic Dentistry - Cosmetic Dental Procedures - Teeth Whitening www.aboutcosmeticdentistry.com/procedures/teeth_whitening.html
About Cosmetic Dentistry - Cosmetic Dental Procedures – Porcelain Veneers www.aboutcosmeticdentistry.com/procedures/porcelain_veneers/index.html
University of Maryland School of Dentistry, Baltimore College of Dental Surgery – Vital Tooth
Bleaching: An Update
www.dental.umaryland.edu/z_dental_archives/dentalprograms_old/ce/Vital%20Tooth%20Bleac
hing%20an%20Update%20by%20Strassler.pdf
Dentalaegis.com – Inside Dental Assisting – Fundamentals of Tooth Whitening
www.dentalaegis.com/ida/2012/02/fundamentals-of-tooth-whitening#sthash.jkJcA6hd.dpuf
Critical Reviews in Oral Biology & Medicine - search for this title at the website: Tooth
Bleaching - A Critical Review of the Biological Aspects - http://cro.sagepub.com
PubMed.gov – search for this title at the website: A review of the efficacy of tooth bleaching www.ncbi.nlm.nih.gov/sites/pubmed
PubMed.gov – search for this title at the website: Evaluation of side effects and patients'
perceptions during tooth bleaching - www.ncbi.nlm.nih.gov/sites/pubmed
Dynamic Dental Educators – Teeth Whitening
18
PubMed.gov – search for this title at the website: Overview of a professional tooth-whitening
system containing 6.5% hydrogen peroxide whitening strips www.ncbi.nlm.nih.gov/sites/pubmed
PubMed.gov – search for this title at the website: A new approach to strip-based tooth whitening:
14% hydrogen peroxide delivered via controlled low dose - www.ncbi.nlm.nih.gov/sites/pubmed
American Heart Association (AHA) - Stroke – search for this title at the website: Cerebral
infarction immediately after ingestion of hydrogen peroxide solution http://stroke.ahajournals.org
Teeth Whitening Product Reviews and Ratings: An unbiased and free resource www.teethwhiteningreviews.com/reviews.php