US Pharm. 2010;35(11):12-15.
The quest for beauty causes some people to subject themselves to painful elective surgery and to undergo dermabrasion, Botox, and other expensive procedures. Esthetic dentistry is one of the more recent procedures that people try in the desire to be beautiful.1 Esthetic dentistry includes orthodontic straightening, use of veneers, and many other processes. One of the most common esthetic procedures is tooth whitening. Patients see their teeth as discolored and wish them whitened, but quite often their self-assessment of discoloration is worse than that of the clinician.2
Causes of Tooth Discoloration
Tooth discoloration arises from intrinsic and extrinsic causes. Intrinsic discoloration can be caused by aging, injury, antibiotic use (e.g., tetracyclines), and fluorosis.3 Extrinsic discoloration is a staining of the tooth surface or the enamel's pellicle coating, and can occur from tea, cofffee, red wine, tobacco, metal salts, chlorhexidine rinse (e.g., Peridex), and poor oral hygiene.3,4 Whitening agents can improve both types of discoloration, although reducing discoloration due to tetracycline is difficult at best.5,6
Peroxides as Whitening Agents
Teeth may be whitened by such methods as air abrasion, composite bonding, veneers, and crowns. A more conservative method is use of chemicals. Chemicals used to whiten teeth include peroxides such as hydrogen peroxide and carbamide peroxide.3 Dental offices usually employ 35% to 37% carbamide peroxide or 15% to 35% hydrogen peroxide, sometimes activated or accelerated by light or laser.7,8 Patients may be given bleaching agents for home use, employing carbamide peroxide or hydrogen peroxide.
Patients may also choose nonprescription whitening products. Products that carry the American Dental Association (ADA) Seal of Acceptance contain 10% carbamide peroxide, although other ingredients and concentrations are eligible for the seal.8 Carbamide peroxide breaks down in an aqueous environment to form hydrogen peroxide and urea.8
While peroxides are well known as bleaching agents for hair and clothing, the method by which they whiten teeth has not been fully elucidated. However, experts theorize that peroxides diffuse into the tooth's outer surface (enamel) and the underlying matrix (dentin). Peroxides become free radicals that are then hypothesized to oxidize and/or reduce large colored organic and inorganic chemicals in the enamel/dentin junction and also in dentin, producing less pigmented molecules.3
Adverse Reactions to Whitening
Patients who undergo whitening in a dental office or use home whitening products may complain of various adverse effects.1 One is tooth sensitivity, occurring in an estimated 15% to 78% of patients.1 The range is wide because the incidence of sensitivity is dependent on the type of procedure utilized, being more likely with higher concentrations and more frequent applications.9 If carbamide peroxide is utilized, the incidence is approximately 67%.9 In most patients, it abates in a few days.1 Coadministration of fluoride during the procedure may reduce the incidence of sensitivity.1 Patients with an increased risk of sensitivity are those whose teeth are already sensitive and those with gingival recession.9 Experts suggest advising patients that there is a 50% risk of mild sensitivity to whitening, a 10% risk of moderate sensitivity, and a 4% risk of severe sensitivity.9
Another problem that may arise from tooth whitening is gingival irritation.1 However, it does not result in permanent gingival damage, and the discomfort usually disappears shortly.1 Gingival irritation is caused by such factors as poor design of the tray used during the procedure, a poorly fitting tray, incorrect application of the bleaching chemical, or direct contact with whitening strips.9
Whitening products should be avoided in patients under the age of 16 years, those who are pregnant or nursing, those with sensitive teeth or an allergy to peroxide, and patients with gingival disease or worn enamel.6
Whitening and Enamel Demineralization
The potential of whitening procedures to permanently damage the teeth is a major reason for caution in their use.1 The concern stems from the theory that the interaction of peroxides with organic and inorganic tooth compounds may cause structural, chemical, and/or mechanical alterations, such as dissolution of enamel. Loss of enamel would begin with removal of calcium ions from the apatite that is the major component of teeth.7
Dental researchers use a novel method to discover whether whitening or any other process causes changes in tooth structure.1 A micrometer-scaled diamond tip is pressed onto tooth enamel. The degree to which the enamel is indented by the instrument is measured to gain a concrete measure of loss of tooth minerals, a method known as microhardness testing. Demonstrated demineralization precedes such noxious processes as dental abrasion, attrition of teeth, and the development of full-blown caries.1 Research has confirmed that whitening with 10% carbamide peroxide predisposed teeth to development of caries.1,7
Whitening Products
Bleaching Strips: The first bleaching strips available on a nonprescription basis were Crest Whitestrips. The product line has undergone several additions and deletions, and the latest Web site now exhibits five separate products, all known as Crest 3D Teeth Whitening Systems.10 The products are designed to cover and whiten teeth that show when the patient smiles.11 All are said to be safe on enamel, and all are once-daily treatments. The Crest 3D Vivid product claims no special features. However, the Advanced Vivid and Professional Effects products promise results after 3 days, featuring an advanced seal technology to provide a stronger grip while in use and also a form fit. The Professional Effects product also offers the highest level of whitening available from Crest in community pharmacies. The Stain Shield product claims to protect against “everyday stain buildup.” Finally, the Gentle Routine product claims to be preferable for teeth that exhibit sensitivity to whitening products.10
The thin, flexible peroxide-coated whitening strips are placed on the teeth, with part of the strip folded behind the teeth to help secure it in place.11 Some strips are designed for the upper teeth and others for the lower, so to ensure optimal fit, they should not be switched. The strips should also be removed when indicated. Patients may notice white spots on the teeth, but they are harmless, caused by water loss from enamel, and will subside. Patients should not eat while strips are in place. They may only drink water if they are using the Advanced Vivid or Professional Effects products, as these are high adhesion.
The products should not be used without consultation with a dental professional if the patient has a cavity, periodontal disease, or a root canal.11 If the strips are used while wearing braces, uneven color could develop. Their ability to whiten teeth affected with fluorosis stains is unknown, and teeth affected by tetracycline may not exhibit profound results. As the strips only whiten natural teeth, they will not affect crowns, caps, fillings, veneers, partial dentures, gold, laminates, composite bondings, or other restorations.
If patients develop tooth sensitivity or gingival discomfort, they should first reduce use to one strip every other day, discontinuing if the problem persists.11 Using a soft-bristle brush or a toothpaste containing potassium nitrate may help prevent sensitivity.
Whitening Toothpastes: Whitening toothpastes (e.g., Crest 3D White Advanced Vivid Toothpaste) have been marketed for many years.12 They typically claim to provide a gentle polishing effect that removes surface stains. Toothpastes such as Rembrandt Plus Peroxide also claim whitening ability through addition of peroxide to the formula.13 Whitening toothpastes accepted by the ADA achieve their effect through gentle polishing, chemical chelation, or other nonbleaching mechanisms.8
Paint-On Gel: At one time, Colgate marketed a paint-on gel containing peroxide, known as Simply White Night. The product line has been discontinued,14 and a thorough search of the manufacturer's Web site fails to provide any information regarding the product.
Whitening Floss: The Reach line of dental flosses once included a floss that claimed to whiten teeth, but apparently this has also been discontinued.15
Probiotic Mint: A product known as EvoraPlus claims to whiten teeth through its inclusion of probiotics.16 It apparently contains Streptococcus uberis, Streptococcus oralis, and Streptococcus rattus. The manufacturer claims that the organisms “release a low level form of hydrogen peroxide as a normal by-product.” The product's label does not include peroxide as an ingredient. It remains to be proven whether a minuscule amount of purported probiotic-produced peroxide could produce any noticeable tooth whitening when medically accepted products must include a quantifiable amount of peroxide as an active ingredient to be efficacious.
Nonperoxide Tooth Whitener: One company markets a system claiming to whiten teeth, without containing peroxide. Natural White 5-Minute Tooth Whitening System, Non-Peroxide Formula, consists of whitening toothpaste, a whitening gel, and an “accelerator.”17 Troublesome ingredients are sodium chlorite in the accelerator and citric acid in the gel. The ADA does not mention these ingredients in its discussion of whitening agents, and the product does not carry the ADA Seal of Acceptance.18,19 Further, that combination of ingredients was found to exert undesirable effects on enamel microhardness when applied to incisors.20
Body Dysmorphic Disorder
Some patients may suffer from body dysmorphic disorder, a preoccupation with a slight or imagined defect, such as tooth whiteness.21 The disorder may cause patients to be dissatisfied with tooth whitening products, no matter how effective they are. For this reason, pharmacists may attempt to explain that a time-consuming preoccupation with tooth whiteness may be equivalent to pursuing the fabled pot of gold at the end of the rainbow, and encourage patients to focus instead on more important aspects of their life.
The quest for beauty places great emphasis on the face, and especially on one's smile. Prior to the 1950s, many people lost teeth due to caries and gum disease. The teeth that remained often jutted out at odd angles, causing malocclusion and embarrassment to the individual when smiling. The advent of fluoridation in the 1950s reduced the number of decayed, filled, and missing teeth. Parents of baby boomers often had the resources to obtain orthodontic work for their children, allowing them to have straighter teeth. One of the final components in creating esthetically pleasing smiles was addressing stained and discolored teeth.
Types of Tooth Stains
There are two types of stains that affect teeth. One is known as extrinsic stains. These are often dark tooth discolorations and can be due to something as simple as what you eat or drink. Highly colored drinks such as colas, coffee, tea, and wine can cause them. Cigarettes and smokeless tobacco also may be responsible for severe tooth staining. Failure to regularly use your toothbrush and floss each day leads to staining as residues slowly build on your teeth. Regular use of a prescription mouthwash known as Peridex (chlorhexidine gluconate) can also cause dental staining. All of these extrinsic stains may occur as uneven discolorations on the teeth, with only a few areas being badly affected. For instance, the areas between the teeth or on their inner sides may be stained due to failure to cleanse. The front teeth may be more stained when coffee is the culprit.
Some people also have intrinsic stains. These are deep stains inside the enamel of the tooth. They are often gray or yellow-brown, being caused by ingestion of medications (e.g., tetracycline during childhood), trauma to the mouth resulting in tooth damage, infection, or natural aging.
Dentist Tooth Whitening
It is a good idea to first ask your dentist about stain treatment, especially if you have a considerable number of crowns, fillings, and/or very dark stains. Dentists can determine the nature of the staining. They may choose to first try certain in-office treatments to reduce intrinsic and/or extrinsic staining. They may also provide products to use at home or suggest that you attempt to use any of several nonprescription products to reduce surface stains.
Prevention of Staining
If you wish to prevent staining, you should first concentrate on the practices and habits known to cause extrinsic staining. Cease use of coffee, colas, tea, and red wine. Stop smoking and using other tobacco products. Having your teeth whitened is of short-term benefit unless you take these measures to keep them white.
Accept Your Appearance
An endless stream of commercials try to make you feel inadequate in many ways. Few are willing to tell people to accept themselves as they are, because that attitude does not sell unneeded products. It may be futile to strive for perfection when aging bodies constantly move from the supposed flawless ideal. Further, misguided people can whiten their teeth until they look exceedingly bright and fake, failing to understand that real beauty begins inside, with a pleasant, caring personality. It may be better to simply accept your appearance in many cases.
REFERENCES
1. Ren YF, Amin A, Malmstrom H. Effects of tooth whitening and orange juice on surface properties of dental enamel. J Dent. 2009;37:424-431.
2. Samorodnitzky-Naveh GR, Grossman Y, Bachner YG, Levin L. Patients' self-perception of tooth shade in relation to professionally objective evaluation. Quintessence Int. 2010;41:e80-e83.
3. Al Machot E, Noack B, Hoffman T. In vitro evaluation of two whitening regimens using color-analyzing methods. Quintessence Int. 2010;41:145-156.
4. Dietschi D, Benbachir N, Krejci I. In vitro colorimetric evaluation of the efficacy of home bleaching and over-the-counter bleaching products. Quintessence Int. 2010;41:505-516.
5. Burrows S. A review of the efficacy of tooth bleaching. Dent Update. 2009;36:537-551.
6. Time for tooth whitening? Harv Women's Health Watch. 2010;17:6.
7. Tezel H, Ertas OS, Ozata F, et al. Effect of bleaching agents on calcium loss from the enamel surface. Quintessence Int. 2007;38:339-347.
8. Statement on the safety and effectiveness of tooth whitening products. American Dental Association. February 2008. www.ada.org/1902.aspx. Accessed September 17, 2010.
9. Burrows S. A review of the safety of tooth bleaching. Dent Update. 2009;36:604-614.
10. Compare Crest 3D White teeth whitening systems. Procter & Gamble. www.3dwhite.com/crest-
11. Crest 3D White frequently asked questions. Special conditions/Usage/Sensitivity. Procter & Gamble. www.3dwhite.com/teeth-
12. Crest 3D White Advanced Vivid Toothpaste. Procter & Gamble. www.3dwhite.com/crest-
13. Rembrandt Plus Peroxide Fresh Mint Toothpaste. McNeil-PPC, Inc. www.rembrandt.com/teeth-
14. Colgate Simply White Night. www.dentist.net/
15. Johnson & Johnson Reach floss. www.dentist.net/johnson-
16. EvoraPlus. Oragenics, Inc. www.evoraplus.com. Accessed September 17, 2010.
17. Natural White 5-Minute Tooth Whitening System, Non-Peroxide Formula. www.drugstore.com:80/products/
18. Tooth whitening treatments. American Dental Association. www.ada.org/2754.aspx. Accessed September 17, 2010.
19. Product search. Whitening. American Dental Association. www.ada.org/productsearch.aspx
20. Zantner C, Beheim-Schwarzbach N, Neumann K, Kielbassa AM. Surface microhardness of enamel after different home bleaching procedures. Dent Mater. 2007;23:243-250.
21. De Jongh A, Oosterink FM, van Rood YR, Aartman IH. Preoccupation with one's appearance: a motivating factor for cosmetic dental treatment? Br Dent J. 2008;204:691-695.
To comment on this article, contact rdavidson@uspharmacist.com.
