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Inside Dental Assisting
Jan/Feb 2012
Volume 8, Issue 1

Fundamentals of Tooth Whitening

Help navigate patients safely through the alternatives

Howard E. Strassler, DMD

In the last 20 years, the options for tooth whitening, also referred to as vital bleaching, have changed significantly with the development of in-office, at-home, and over-the-counter (OTC) techniques.1,2 Because of a bewildering array of choices, many patients consult oral healthcare professionals, who can be a valuable source of information. Patient education, which includes keeping a patient’s expectations realistic, is an essential part of helping to provide guidance for whether to choose whitening and which products and treatments are the most suitable.

Tooth whitening is considered any process that will make teeth appear lighter.3 Typically, whitening, when used in appropriate patients, will provide improvements in tooth color.4 Tooth whitening is considered to be one of the most conservative and cost-effective treatments for smile esthetics.2

Candidates for Whitening

Tooth whitening is best performed under the care of a dental team. Not all patients will benefit from whitening or are appropriate candidates for the procedure and it is recommended the patient have a clinical evalulation to understand why the teeth are discolored. The causes of discolored teeth vary from extrinsic (related to outside causes, staining of the enamel) to intrinsic sources (staining of the dentin).4,5 Enamel is susceptible to staining because it is inherently porous at the microscopic level. Determining the cause is essential because the type of discoloration will determine if tooth whitening is the appropriate treatment. For some patients, tooth discoloration may be a sign of disease or condition that requires dental treatment.2 Professional whitening (vital bleaching) targets staining of the enamel (extrinsic staining), which cannot be removed during thorough mechanical scaling and polishing.4 Some extrinsic staining may be very resistant to tooth whitening.

Extrinsic causes, or surface stains (enamel staining), include4,5:

  • High levels of fluoride
  • Foods, such as blueberries, carrots, and oranges
  • Liquids, such as coffee, tea, purple grape juice, and wine
  • Tobacco products, especially smoking


Intrinsic stains (dentin staining) include1,2,5:

  • Certain medications such as tetracycline
  • Color change secondary to tooth trauma
  • Developmental disorders
  • Tooth decay


Clinical decisions regarding tooth whitening are based on the patients’ desires to whiten their teeth, a history of allergies (particularly in regard to bleaching materials), and information regarding tooth sensitivity.2 The most important consideration before starting any tooth whitening procedure is the diagnosis for the tooth discoloration. Vital bleaching is usually for teeth that are discolored in the enamel (extrinsic staining) and not for teeth with darkening due to endodontic reasons (intrinsic staining). Patients with bonded restorations or crowns on front teeth may not be good candidates for whitening unless as part of the plan the restorations will be replaced to the new tooth color after bleaching. When a dental team is deciding the best course of whitening treatment, it is best to understand patient expectations, limitations, and willingness to follow a course of treatment.4

Where to Start

Before any treatment is initiated and in order to obtain optimal results, dental professionals should begin with patient education. In some offices, a part of the dental assistant’s role in providing optimal care involves presenting to the patient all potential treatment plans, including smile esthetics.4 Patients should understand options, expectations, safety, and possible side effects. They should also be advised of the importance of a dental examination before embarking on any whitening treatment, whether professionally supervised or self-administered.2 It is important to understand that whitening occurs in a sensitive oral environment.5

To facilitate discussions with their patients, assistants can obtain educational materials from the Web sites of the American Dental Association ( and the American Academy of Cosmetic Dentistry ( Manufacturers also have educational brochures.

Taking an Assessment

Whitening treatment starts with a healthy mouth.6 The presence of tooth decay, sensitive or cracked teeth, infection, periodontal disease, or other problems could affect the course of treatment and degree of adverse effects.6 These problems should be addressed before any tooth whitening is performed.6 Patients should understand that whitening does not remove tooth decay or change the color of existing restorations.

What Whitening Will Not Do

Patients should be advised that whitening will not whiten crowns, veneers, bonding materials, or tooth-colored fillings.6 Yellowish teeth are more likely to bleach well, brownish teeth less well, and grayish teeth may not bleach well.7 Bonding or tooth-colored fillings on the front teeth will be obvious if whitening is performed on natural teeth because bleaching will not change the color of restorations.7 In these cases, porcelain veneers or dental bonding might be better options than whitening.2

Tooth bleaching works well in lightening discoloration caused by age, food staining, and staining from certain beverages (eg, tobacco, coffee, and tea). An estimated 96% of patients with these kinds of stains see some improvement.8

Active Ingredients

The active ingredient in most professionally dispensed whitening techniques is hydrogren peroxide or carbamide peroxide (which becomes hydrogen peroxide during treatment). To improve the acceptance of these peroxides, there are additives for flavor, color, desensitizing and viscosity.9 Peroxide-based whitening products work on the enamel surface10 and have the potential to remove accumulated stains. When these agents contact the teeth, the oxidation process dissolves internal and surface stains.10 The oxidizing agent enters the enamel and dentin to create a chemical action with discolored particles.9

Higher concentrations produce a faster result.9 However, higher concentrations may increase tooth sensitivity,9 and patients should be advised accordingly.


Published studies suggest that bleaching is a relatively safe procedure when proper protocols, including infection control, are followed2,6; however, research is ongoing regarding the adverse effects on hard and soft tissues, as well as restorative materials.2 The rate of adverse effects from use or abuse of OTC products remains unclear because consumers may not be reporting problems through the US Food and Drug Administration (FDA) Medwatch.2

The American Dental Association (ADA) and the American Academy of Cosmetic Dentistry (AACD) have expressed concern about the administration of whitening in nondental settings, such as malls and salons.2,11 Some states have begun to restrict this practice. These organizations note that these services are being provided without the benefit of fully trained and licensed oral healthcare professionals. This could present health risks to patients. A major concern is that people seeking whitening services without a dental evaluation and diagnosis may not receive treatment for more serious conditions such as decay close to the pulp. This could result in permanent problems, including a dental abscess and need for root canal treatment or extraction.11 Nondental professionals do not have the appropriate training to aid in diagnosis or to raise concern about disease being the cause of discoloration.2,11

Currently, whitening products are developed and marketed according to the cosmetic regulations of the FDA.12 Under this definition, no cosmetic may be labeled or advertised with statements suggesting that the FDA has approved the product.12 The FDA has noted that it does not have the resources or authority for premarket approval of cosmetic product labeling and the manufacturer or distributor is responsible for ensuring that products are labeled properly.12 The ADA has expressed concern regarding this classification and notes that patients and consumers may falsely believe that these products are harmless. Poor-quality products may increase the risk of some adverse effects.2

Evidence is not clear regarding safety of tooth whitening in pregnant women. Oral healthcare professionals may want to consider advising these patients to postpone treatment.2 In addition, the ADA has found that the evidence is not clear regarding children and teenagers and suggests close professional and parent/guardian supervision is necessary for these age groups.2

Adverse Effects

Sensitivity and gingival irritation may occur.5 Higher concentration hydrogen peroxide products used for in-office whitening can contact the soft tissues and create a chemical burn, possibly creating some mild discomfort.9 The use of a dental dam or other protective barrier is recommended during treatment to protect the tissues. In-office systems usually include a light-cured resin to apply to cervical areas to retain the agent.9

Tooth sensitivity is common, occurring in up to 50% of patients receiving whitening treatment. Patients should be warned that this problem may occur. However, sensitivity may be hard to predict.9 Those with large pulps, loss of enamel, or carious lesions can be at greater risk for sensitivity related to tooth whitening.9 For in-office whitening for patients not allergic to aspirin, non-steroidal anti-inflammatory medications one hour prior to treatment and appointments spaced 1 week apart may help.2 For patients with sensitivity when using tray bleaching, research has shown that bleaching products with desensitizing agents and the use of a desensitizing toothpaste with 5% potassium nitrate helps alleviate this problem. The clinician will be able to make these decisions so the patient is comfortable during the procedure.9

Signs of overuse or adverse events include overwhitening and gingival damage.5 Overuse of OTC products can cause erosion of tooth enamel. This is especially true with solutions containing acid.

Treatment Options

Professionally Applied Treatment

Also known as chairside whitening, professional whitening techniques provide the most dramatic results.4 These products have 15% to 35% concentrations of hydrogen peroxide and sometimes involve a light or laser, which may help accelerate the whitening process. Many research studies have shown that the use of a light or laser is optional, but for some patients the use of the device enhances their experience. This concentration is higher than at-home and OTC products.3 Teeth can brighten 10 shades in approximately an hour,1 and results are immediate compared with at-home treatments, which may take 2 to 4 weeks.3,10 Some treatments may require more than one office visit; the average number of visits is 3.2

At-Home Techniques

At-home dentist-supervised techniques provide the patient with the benefit of more comfortable whitening procedures compared with OTC products. Trays are customized to fit the patient. Some at-home products that have the ADA Seal of Acceptance contain a concentration of 10% carbamide peroxide.3

These products work quickly. Depending on the severity of the tooth discoloration, some products are used twice daily for 2 weeks and others are used overnight for 1 to 2 weeks.7 Mouth trays are made in 1 office visit.

These treatments are effective with many kinds of stains, and the improvement can be as much as 6 shades with long-lasting results10 (Figure 1, Figure 2, Figure 3 and Figure 4). These may cause temporary sensitivity.

Over-the-Counter Products

OTC products on the market today include gels, paint-on tooth gel, mouth trays with gel, whitening toothpaste, and whitening gum. These are available without dentist supervision and generally do not provide the same dramatic improvement as seen with professional treatment10 or supervised treatment. The OTC products containing 10% peroxide are eligible for the ADA Seal of Acceptance.3 They can be effective for age-related staining and slight diet-related staining.10 Their effectiveness can last 6 months, and they can result in a 2-shade improvement and can help maintain professional whitening results.10

Unsupervised use of these products can be an issue because of the possibility of undiagnosed or underlying disease, cosmetic or functional aspects of existing dental restorations, and unknown allergies.2 A consumer’s expectations may not be realistic.2

Whitening Toothpaste

The mild abrasiveness of whitening toothpastes removes surface stains. They typically provide temporary results with a slight shade improvement and may be useful for maintaining professional treatment results.10 Products with the ADA Seal of Acceptance for whitening have special chemical or polishing agents for additional stain removal effectiveness.7


Patients prize the value of an esthetic smile, however the assortment of treatment options can be confusing. Evidence-based patient education is the cornerstone of oral healthcare, and dental assistants can play a key role in helping to provide solid answers regarding tooth whitening and guiding a patient in treatment decisions.


1. Teeth whitening. American Academy of Cosmetic Dentistry Web site. Accessed January 18, 2012.

2. American Dental Association Council on Scientific Affairs. Tooth whitening/bleaching: treatment considerations for dentists and their patients. American Dental Association Web site. Accessed January 18, 2012.

3. Statement on the safety and effectiveness of tooth whitening products. American Dental Association Web site. Accessed January 18, 2012.

4. Bernie KM. Professional whitening. Accessed January 18, 2012.

5. Scarlett MI. Home-based whitening systems—how to advise patients. Inside Dental Assisting. 2009;5(4 suppl);26-26.

6. ADA, Journal of the American Dental Association, ADA Division of Science. For the dental patient. Tooth whitening: what you should know. J Am Dent Assoc. 2009;140(3):384.

7. Tooth whitening. American Dental Association Web site. Accessed January 18, 2012.

8. Tooth whitening systems. American Dental Hygienist Association Web site. Accessed January 18, 2012.

9. Marshall K, Berry TG, Woolum J. Tooth whitening: current status. Compen Contin Educ Dent. 2010;31(7): 486-496.

10. Bernie KM. Get the facts on tooth whitening. Accessed January 18, 2012.

11. American Academy of Cosmetic Dentistry statement regarding teeth whitening procedures. American Academy of Cosmetic Dentistry Web site. Accessed January 18, 2012.

12. US Food and Drug Administration. Cosmetic Labeling & Label Claims. April 25, 2006. Accessed January 18, 2012.

About the Author

Howard E. Strassler, DMD
Department of Endodontics, Prosthodontics and Operative Dentistry
University of Maryland Dental School
Baltimore, Maryland

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