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74
Test 81.1
AESTHETICS
Current Status of Tooth Whitening
Literature Review
he use of hydrogen peroxide in dentistry can be traced back more than
100 years.1-4 Initially, hydrogen peroxide was evaluated for use in periodontal
treatment and wound healing. Studies have
substantiated that hydrogen peroxide can
prevent and delay the colonization and replication of anaerobic bacteria.5,6 This reduction
in the microflora, with subsequent reduction
in the levels of plaque accumulation, resulted
in better gingival health.7 Furthermore,
wound healing following periodontal surgery
was enhanced as a result of the antimicrobial
effects of topically administered hydrogen
peroxide.8
Bleaching agents are compounds that are
used to remove color from substances, and
most are oxidizing agents such as hydrogen
peroxide, which are effective in “decolorizing”
substances via oxidation. The decolorizing
action of bleaches is due in part to their ability to remove electrons, which are activated by
T
Len Boksman,
DDS
Dental clinicians are in a unique position to
play an active role in encouraging and educating dental patients regarding the choices
that are available for tooth whitening. Tooth
whitening is the easiest and least expensive of
the treatment options that are available to
change the shade of the dentition.
visible light to produce various colors.9 In
1966 Schneider, et al10 documented the use of
a peroxide-containing gingival strip to apply
peroxide to healing periodontal tissues. Tooth
whitening was later observed as an unintentional side effect when hydrogen peroxide was
used in periodontal treatment.11 In the late
1960s Klusmier noticed the whitening effect
when using Gly-Oxide (GlaxoSmithKline) in
orthodontic positioners.12 Later, Wagner used
Proxigel (Reed and Carnrick Pharmaceutical)
in custom-fitted vacuum-formed trays specifically for tooth whitening. These were FDAapproved oral antiseptics containing 10% carbamide peroxide.13
In 1989, Heymann and Haywood published a report that introduced the concept of
using a nightguard with a viscous whitening
solution that contained a thickening agent
(Carbopol). The viscosity of the solution alDENTISTRY TODAY • SEPTEMBER 2006
lowed for a longer bleach time and increased
retention in the tray.14 In 1989 Fischer, who
created Opalescence carbamide peroxide
(Ultradent Products), received a patent for a
thick and sticky whitening gel formulation
that is still the basis for most night-time gels
in use today. Carbamide peroxide breaks
down into hydrogen peroxide and urea; hydrogen peroxide breaks down into oxygen and
water; urea breaks down into ammonia and
carbon dioxide. This was the first ADAapproved system for whitening.13 This product was developed with a high water content
to minimize tooth sensitivity, a neutral pH, a
thixotropic viscosity to improve retention in
the tray, and sustained release of the hydrogen peroxide. With this introduction of home
whitening, there has been explosive growth in
consumer awareness and use of tooth-whitening systems. There are literally hundreds of
competing products and delivery systems for
in-office and home use. However, all systems
employ the basic principles of exposing the
discolored dentition to various forms of hydrogen peroxide over time.
The safety of hydrogen peroxide and carbamide peroxide has been documented in
numerous studies. Haywood and Heymann15
evaluated vital bleaching using 10% carbamide peroxide in a nightguard, stating that
“concerns of toxicity or damage to hard and
soft tissues appear unfounded.” In a retrospective review of the medical and dental literature Yarborough16 states that “the safety
and efficacy of hydrogen peroxide is wellestablished.” Hydrogen peroxide does not
adversely affect enamel morphology or microhardness, and it is not expected to inhibit pulpal enzymes.17 Even when used for extended
periods of time when treating tetracyclinestained teeth, no adverse effects have been
noted using carbamide peroxide.18
EXTRINSIC AND INTRINSIC STAINS
Dental discoloration can be due to extrinsic
staining, which is superficial and affects only
the enamel surface. This type of discoloration is
associated with the use of tea, coffee, chewing
tobacco, some foods such as blueberries, and red
wine. In addition, teeth discolor in association
with aging. This type of discoloration is relatively easy to treat with tooth whitening. The
intrinsic stains that discolor the tissues of the
tooth (enamel, dentin), such as that related to
fluorosis or tretracycline (Figures 1 to 3), are
Figure 1. A 45-year-old male demonstrating tetracycline
staining and a nonvital tooth No. 9. (Figures 1 to 9 are
courtesy of Dr. Bruce Matis.)
Figure 2. The patient after 4 months of take-home
whitening.
Figure 3. Three months post bleaching.
much more difficult to treat. Even though peroxides in whitening systems have been shown
to rapidly permeate intact enamel, dentin,
and pulp,19 changing the color of the dentin
requires long exposure to produce any noticeable effect. Hydrogen peroxide releases oxygen that breaks down conjugated bonds in
protein chains associated with stain into a single bond. This results in more absorption of
color wavelengths, resulting in the reflection of
little color (ie, a whitening effect).20
continued on page 76
76
AESTHETICS
Current Status...
continued from page 74
In-office whitening is
best for those patients
who desire a quick
result and for those
who need close monitoring for clinical
conditions such as
pronounced gingival
recession or deep,
unrestored abfraction
lesions.
IN-OFFICE WHITENING
In-office tooth whitening is
associated with a higher cost
than take-home whitening
systems due to chair time. Inoffice whitening is best for
those patients who desire a
quick result and for those
who need close monitoring for
clinical conditions such as
pronounced gingival recession or deep, unrestored abfraction lesions. It is also necessary for tooth discoloration
associated with endodontic
therapy. In-office tooth whitening using high concentrations of hydrogen peroxide is
not new. Boksman, et al published articles in the 1980s on
the use of heated Superoxol
(Sultan Healthcare) hydrogen
peroxide (30%).21-24
Many current systems use
light activation in conjunction with hydrogen peroxide.
Examples include the following: LaserSmile (Biolase Technology) 37% hydrogen peroxide; ArcBrite (Biotrol) 30%
hydrogen peroxide; BriteSmile (BriteSmile) 15% hydrogen peroxide; Rembrandt
Lightning Plus (Johnson &
Johnson) 35% hydrogen per-
oxide; Zoom (Discus Dental)
20% hydrogen peroxide; and
LumaWhite Plus (LumaLite)
35% hydrogen peroxide.
Because of media coverage
about light-activated bleaching, patient demand for this
process is increasing. It is
interesting to note that clinical trials repeatedly show
that light and heat do not
increase the efficacy of tooth
whitening and are not necessary for vital tooth bleaching.
Contact time and concentration of active ingredients are
the critical factors.25
Light-activated whitening
systems offer a marketing opportunity but add cost, occupy
operatory space, can cause
burning of the soft tissue, and
can increase operatory temperature.26 All systems recommend a take-home tray as
an adjunct, so the question is
whether any observed benefit
is due to the light or the
tray.27 It is also important to
note that many drugs patients may be using cause
minor to marked photosensitivity and hyperpigmentation. These include acne medications, anticancer drugs,
antidepressants, antihistamines, antimicrobials, antiparasitic drugs, antipsychotic
drugs, diuretics, hypoglycemics, and nonsteroidal antiinflammatory drugs.28 Therefore, the use of a light for
in-office whitening may not
be justified due to the risks
involved.
In-office whitening systems not using light or heat
include the following: Illuminé with 15% hydrogen peroxide (DENTSPLY Professional); OfficeWhite with 40%
hydrogen peroxide (Life-Like
Cosmetic Solutions); Perfection White with 35% hydrogen peroxide (Premier Dental
Products); Niveous with 25%
hydrogen peroxide (Shofu
Dental); and Opalescence Xtra
Boost (Ultradent Products)
with 38% hydrogen peroxide
(Figures 4 to 6). Due to the
adverse effects these high
concentrations of hydrogen
peroxide can have on the gingival tissues, many of these
systems utilize various forms
of tissue protection to minimize the potential for damage. The time of application
and number of applications
vary by product.
Figure 5. Opalescence Xtra Boost
gel on teeth, with OpalDam (Ultradent Products) protecting the gingival
tissues and covering the gingival
margin of the tooth by 0.5 mm.
Figure 6. After three, 15-minute
applications of Opalescence Xtra
Boost (at one appointment).
Figure 7. Prewhitening.
Figure 8. Same patient after whitening maxillary dentition with 10%
Opalescence.
Figure 9. Same patient after whitening the mandibular arch.
JustSmile (JustSmile Whitening Systems) 2% to 10%
hydrogen peroxide; Perfecta
Bravó (Premier Dental Products) 9% hydrogen peroxide;
and PolaDay (Southern Dental Industries) 3%, 7.5%, and
9.5% hydrogen peroxide.
A product recently introduced by Ultradent Products
is Trèswhite. The inner tray,
containing 9% hydrogen peroxide gel, has a gingival barrier protector gel around the
sides. This prefabricated system utilizes an outer overtray, which carries the inner
tray to the mouth and is then
removed, leaving the inner
tray containing the bleaching
material adapted to the teeth
(Figure 10).
The effects of hydrogen
peroxide and carbamide peroxide on enamel have been
extensively studied. Araujo,
et al looked at the effect of
10% carbamide peroxide on
the microhardness of human
enamel and found that bleaching with carbamide peroxide
is safe for human enamel.31
When evaluating peroxide
bleaching on enamel surfaces,
White, et al found that there
was no decrease in surface
hardness measurements as-
sociated with tooth bleaching.32 Clark looked at the application of fluoridated 10%
carbamide peroxide on enamel and found demineralization inhibition comparable to
toothpaste of similar fluoride
concentration.33 In a recent
study by Al-Qunaian, Opalescence PF 20% showed an
enamel surface that was less
susceptible to caries than the
control. 34 However, when
looking at the effects of 7 carbamide peroxide bleaching
agents on enamel microhardness over time, Basting found
that enamel treated with different bleaching agents or a
placebo experienced a similar decrease in microhardness values over time, with
the exception of (enamel)
fragments exposed to Opalescence PF 20%.35
With the take-home systems, custom trays are fabricated to “trap” the agent
against the tooth surface. A
reservoir created by placing a
die spacer over the teeth can
be created, or alternatively no
die spacer is used. The reservoir technique creates a small
space on the inside surface of
the tray immediately adjacent to the buccal surface of
TAKE-HOME WHITENING
At-home systems for tooth
whitening, utilizing tray delivery of the whitening agent,
have been extensively studied
since their introduction by
Heymann and Haywood 14
(Figures 7 to 9). The degradation of carbamide peroxide occurs over time. After 2 hours,
more than 50% of the active
agent is available, and 10%
is available after 10 hours.29
Therefore, for use at night,
the maximum whitening effect occurs in the first 2
hours. Whitening agents that
are recommended by their
manufacturers for night-time
use include the following:
Opalescence PF (Ultradent
Products) 10%, 15%, and 20%
carbamide peroxide; Nupro
White Gold (DENTSPLY Professional) 10% and 15% carbamide peroxide; Nite White
Turbo (Discus Dental) 6%
hydrogen peroxide; and PolaNight (Southern Dental Industries) 10%, 16%, and 22%
carbamide peroxide.
For daytime use, both carbamide peroxide and hydrogen peroxide are effective athome bleaching agents.30
Products indicated by their
manufacturers for daytime
use include the following:
Opalescence PF 10%, 15%,
and 20% carbamide peroxide;
Rembrandt XTRA-Comfort
(Johnson & Johnson) 16%,
22%, and 30% carbamide
peroxide; Natural Elegance
(Henry Schein) 10%, 15%,
and 22% carbamide peroxide;
FREEinfo, circle 51 on card
DENTISTRY TODAY • SEPTEMBER 2006
Figure 4. Preoperative photograph
of 46-year-old female requesting inoffice whitening.
77
AESTHETICS
the tooth. This space will trap
a greater quantity of bleach
than a nonreservoir technique. The increased bleach
quantity will release more
oxygen ions over a longer
period of time in the vicinity of the tooth, creating a
greater early whitening effect. 36 Using colorimetric
analysis, a study by Matis
found that teeth lightened
with trays containing a reservoir were lighter in color than
teeth lightened with trays
that did not have a reservoir.
However, the difference was
below the threshold of visual
detection.37 It is also of importance to note that the
amount of active material left
after a period of time varies
with tray design. In a study
looking at the total carbamide peroxide percent recovered after timed use in
various tray designs, Matis,
et al demonstrated that the
use of reservoirs resulted in a
recovery of significantly higher carbamide peroxide after 2
hours.38 The use of reservoirs
may or may not be necessary,
with published data supporting both points of view39
(Figures 11 to 14).
Sales of over-the-counter
whitening products have been
estimated to approach $1 billion a year in North America
alone.13 Companies (eg, Procter & Gamble, Colgate) offer
whitening products whose effects have been documented. 40,41 Crest Whitestrips
(Procter & Gamble), containing a 6.5% hydrogen peroxide,
were introduced in 2001.
Many different versions of
Colgate Platinum are available. Initially offered as
whitening strips of various
concentrations of hydrogen
peroxide, a new delivery system utilizing a gel that is
painted on the teeth (Colgate
Simply-White Whitening Gel)
containing 5.9% hydrogen
peroxide has recently been
introduced; it exceeds the
ADA minimum requirements
to claim “clinical efficacy.”42
sensitivity. 43 If sensitivity
occurs, the easiest way to
address the problem is to
decrease the time the patient
treats the teeth or decrease the
dosage of the peroxide or car-
bamide peroxide. Many products contain water to decrease
the dehydration effects of whitening (Opalescence). Fluoride
and potassium nitrate have
been added to certain products
such as Opalescence PF to
decrease the incidence of tooth
sensitivity. Potassium nitrate
penetrates the dentinal tubules and depolarizes the
nerves, decreasing the painful
TOOTH SENSITIVITY
Transient tooth sensitivity occurring after whitening teeth
with the products described
in this article is dose and
time dependent. The higher
the dose or concentration of
the whitening agent and the
longer the teeth are exposed,
the greater the risk of tooth
FREEinfo, circle 52 on card
stimulus.44 Potassium nitrate
gels, which can be used in
bleaching-type trays to reduce
hypersensitivity of root surfaces, include UltraEZ (Ultracontinued on page 78
78
AESTHETICS
Current Status...
continued from page 77
dent Products), Den-Mat Desensitize (Den-Mat), and Relief
(Discus Dental). A pre-loaded
tray version of UltraEZ is
also available. Recently, amorphous calcium phosphate was
added to products like Zoom2
(Discus Dental) to treat hypersensitivity.
CONCLUSION
Dental clinicians are in a
unique position to play an
active role in encouraging
and educating dental patients regarding the choices
that are available for tooth
whitening. Tooth whitening is
the easiest and least expensive of the treatment options
that are available to change
the shade of the dentition.F
Figure 10. Trèswhite with 9% hydrogen peroxide gel and an outer gingival protector gel.
Figure 11. Application of LC BlockOut Resin (Ultradent Products) on
the labial surfaces of the teeth to
be whitened.
Figure 12. Tray material in UltraVac
Vacuum Former (Ultradent Products)
showing a 2-inch drop of the tray
material when heated sufficiently.
Figure 13. Ultra-Trim Scalloping
Scissors (Ultradent Products) scalloping the gingival margins to adapt
precisely to the gingival margin.
Figure 14. Tray perfectly trimmed to
the gingival margin, showing labial
reservoir outline.
References
1. Burchard HH. A Textbook of Dental
Pathology and Therapeutics. Philadelphia, Pa: Lea and Febiger; 1898.
2. Fitch CP. Etiology of the discoloration
of teeth. Dental Cosmos. 1861;3:133136.
3. Harlan AW. Hydrogen dioxide (in the
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4. White JD. Bleaching. Dental Register
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5. Wennstrom J, Lindhe J. Effect of
FREEinfo, circle 53 on card
79
AESTHETICS
hydrogen peroxide on developing
plaque and gingivitis in man. J Clin
Periodontol. 1979;6:115-130.
6. Volpe AR, Manhold JH, Manhold BS,
et al. Gingival tissue oxygenation: the
effect of a single application of four
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7. Kelly TF. Hydrogen peroxide shows
value of use. Dent Stud. 1976;54:66,82
8. Marshall MV, Cancro LP, Fischman
SL. Hydrogen peroxide: a review of its
use in dentistry. J Periodontol.
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9. Asato R. Oxidation/reduction: bleaching agents. Kapi’olani Community
College Web site. Available at:
http://library.kcc.hawaii.edu/external/c
hemistry/everyday_bleach.html.
Accessed May 6, 2006.
10. Schneider HG, Birkholz C, Hampel W.
Clinical experience with the peroxidecontaining gingival strip from the
Leipziger Arzneimttelwerk. Dtsch
Stomatol. 1966;16:656-667.
11. Flaitz CM, Hicks MJ. Effects of carbamide peroxide whitening agents on
enamel surfaces and caries-like lesion
formation: an SEM and polarized light
microscopic in vitro study. ASDC J
Dent Child. 1996;63:249-256.
12. Goff S. Getting the white right. Dental
Products Report. Jan 2005:14-19.
Available at: http://www.dentalproducts.net/xml/display.asp?file=2716&b
hcp=1. Accessed July 20, 2006.
13. Fasanaro TS. Bleaching teeth: history,
chemicals, and methods used for
common tooth discolorations. J Esthet
Dent. 1992;4:71-78.
14. Haywood VB, Heymann HO. Nightguard vital bleaching. Quintessence
Int. 1989;20:173-176.
VB,
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Nightguard vital bleaching: how safe is
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16. Yarborough DK. The safety and efficacy of tooth bleaching: a review of the
literature 1988-1990. Compendium.
1991;12:191-196.
17. Pugh G Jr, Zaidel L, Lin N, et al. High
levels of hydrogen peroxide in
overnight tooth-whitening formulas:
effects on enamel and pulp. J Esthet
Restor Dent. 2005;17:40-47.
18. Haywood VB, Leonard RH, Dickinson
GL. Efficacy of six months of nightguard vital bleaching of tetracyclinestained teeth. J Esthet Dent.
1997;9:13-19.
19. Cooper JS, Bokmeyer TJ, Bowles
WH. Penetration of the pulp chamber
by carbamide peroxide bleaching
agents. J Endod. 1992;18(7):315-317.
20. Wade LG Jr. Conjugated systems. In:
Organic Chemistry. 3rd ed. Upper
Saddle River, NJ. Prentice Hall; 1994:
chapter 15, 695, 1106.
21. Boksman L, Jordan RE. Conservative
treatment of the stained dentition: vital
bleaching. Aust Dent J. 1983;28:6772.
22. Jordan RE, Suzuki M, Hunter JK, et al.
Conservative treatment of the tetracycline stained dentition. Alpha
Omegan. 1981;74:40-49.
23. Boksman L, Jordan RE, Skinner DH. A
conservative bleaching treatment for
the
nonvital
discolored
tooth.
Compend
Contin
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1984;5:471-475.
24. Jordan RE, Boksman L. Conservative
vital bleaching treatment of discolored
dentition. Compend Contin Educ
Dent. 1984;5:803-807.
25. CRA Newsletter. Issue 4, 2000.
26. CRA Newsletter. Issue 26, 2002.
27. Kugel G. Is there a benefit to light-activated tooth whitening? J Can Dent
Assoc. 2005;71:420-421.
28. Drug-induced photosensitivity. Family
Practice Notebook.com. Available at:
http://www.fpnotebook.com/DER202.h
tm. Accessed May 6, 2006.
29. Matis BA, Gaiao U, Blackman D, et al.
In vivo degradation of bleaching gel
used in whitening teeth. J Am Dent
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30. Mokhlis GR, Matis BA, Cochran MA,
et al. A clinical evaluation of carbamide peroxide and hydrogen peroxide whitening agents during daytime
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131:1269-1277.
31. Araujo EM, Baratieri LN, Vieira LC, et
al. In situ effect of 10% carbamide peroxide on microhardness of human
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32. White DJ, Kozak KM, Zoladz JR, et al.
Peroxide interactions with hard tissues: effects on surface hardness and
surface/subsurface
ultrastructural
properties. Compend Contin Educ
Dent. 2002;23:41-48.
33. Clark LM, Barghi N, Summitt JB, et al.
Influence of fluoridated carbamide
peroxide bleaching gel on enamel
demineralization. Abstract 0497.
International Association for Dental
Research Web site. Available at:
http://iadr.confex.com/iadr/2006Orld/t
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Accessed May 2006.
34. Al-Qunaian T. The effect of whitening
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enamel.
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35. Basting RT, Rodrigues AL Jr, Serra
MC. The effects of seven carbamide
peroxide bleaching agents on enamel
microhardness over time. J Am Dent
Assoc. 2003;134:1335-1342.
36. Buyers’ guide to whitening systems.
Dent Today. Dec 2004;23(12):120.
37. Matis BA, Hamdan YS, Cochran MA,
et al. A clinical evaluation of a bleaching agent used with and without reservoirs. Oper Dent. 2002;27:5-11.
38. Matis BA, Yousef M, Cochran MA, et
al. Degradation of bleaching gels in
vivo as a function of tray design and
carbamide peroxide concentration.
Oper Dent. 2002;27:12-18.
39. Javaheri DS, Janis JN. The efficacy of
reservoirs in bleaching trays. Oper
Dent. 2000;25:149-151.
40. Gerlach RW, Zhou X. Clinical trial
comparing two daytime hydrogen-peroxide professional vital-bleaching systems. Compend Contin Educ Dent.
2004;25(8 suppl 2):33-40.
41. Sagel PA, Landrigan WF. A new
approach to strip-based tooth whitening: 14% hydrogen peroxide delivered
via controlled low dose. Compend
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42. Gambarini G, Testarelli L, De Luca M,
et al. Efficacy and safety assessment
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containing 5.9% hydrogen peroxide.
Am J Dent. 2004;17:75-79.
43. Boksman L. A large proportion of the
patients who undergo teeth whitening
procedures in my office experience
sensitivity. How can I minimize this
side effect? J Can Dent Assoc. Dec
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Continuing Education
Test No. 81.1
T
o submit Continuing Education answers, use the answer sheet on page 73. On the
answer sheet, identify the article (this one is Test 81.1), place an X in the box corresponding to the answer you believe is correct, detach the answer sheet from the
magazine, and mail to Dentistry Today Department of Continuing Education.
The following 8 questions were derived from the article Current Status of Tooth Whitening:
Literature Review by Len Boksman, DDS, on pages 74 through 79.
Learning Objectives
After reading this article, the individual will learn:
• about the development of bleaching agents, and
• how to choose the appropriate tooth-whitening system for each patient.
1
Hydrogen peroxide in dentistry ____.
5
a. has been in use for more than 100
years
b. has been found to promote bone
healing
c. has no antimicrobial effects
d. cannot be used in conjunction with
d. tetracycline
In-office tooth whitening is best for ___.
a. patients with time limitations
b. patients who need close monitoring
c. teeth that have been endodontically
treated
d. all of the above
6
For in-office tooth whitening, _____.
periodontal surgery
a. heat increases the whitening effect
b. light increases the whitening effect
c. concentration is the only critical
factor that determines the degree of
whitening
d. contact time and concentration of
active ingredients are the critical
factors
2
The carbamide peroxide reaction is
defined as follows:
a. Carbamide peroxide degrades
into hydrogen peroxide and water.
b. Carbamide peroxide degrades
into oxygen and water.
c. Carbamide peroxide degrades
into ammonia and carbon dioxide.
d. Carbamide peroxide degrades
into hydrogen peroxide and urea.
7
Hydrogen peroxide _____.
a. increases enamel’s susceptibility to
develop caries
b. decreases the microhardness of
enamel
c. in Opalescence PF decreases susceptibility for caries
d. with fluoride added is not absorbed
into enamel
3
Dr. Boksman is adjunct clinical professor at the Schulich School of
Medicine and Dentistry, University of
Western Ontario. He is a fellow in the
Academy of Dentistry International
and in the International College of
Dentists. He can be reached at (519)
641-3066, extension 292, or [email protected].
Disclosure: Dr. Boksman holds a
paid part-time consulting position
with Clinicians Choice and Clinical
Research Dental, with the title of
director of clinical affairs.
Hydrogen peroxide in all whitening
agents _____.
a. is toxic to soft tissues
b. is safe to use
c. is detrimental to the pulp
d. decreases the microhardness of
enamel
8
Tooth sensitivity during whitening ____.
4
Which of the following is not an
intrinsic stain?
a. nicotine staining
b. fluorosis
c. amalgam staining
a. can be treated by decreasing dosage
and time of whitening
b. can be treated with potassium nitrate
to depolarize nerves
c. can be reduced by using agents that
contain water
d. all of the above
Continuing our “Journey of Excellence”
SEPTEMBER 2006 • DENTISTRY TODAY