Exploring the Evolving Landscape of Tooth Whitening

Tooth whitening is among the growing trends in health, wellness, and lifestyle industries. Consumers often seek to whiten their dentition as a way to enhance their smile.¹ Globally, the United States leads the whitening market, an annual billion-dollar industry. In addition, a study by the American Academy of Cosmetic Dentistry illustrates that more than 90% of Americans perceive the smile as their most critical social asset.²

An attractive smile can increase individuals’ confidence in both personal and professional settings. A whiter smile may also motivate patients to eliminate unhealthy behaviors such as smoking.^2,3

In many states, peroxide-containing whitening products are considered cosmetics, therefore, it is legal for nondental providers to provide in-office tooth whitening and dispense professional take-home whitening products. Dentists and dental organizations have tried to impose bans on tooth whitening procedures in nondental settings. In 2013, a report by the Institute of Justice examined the risks of tooth-whitening done by nondental professionals according to complaints filed with state agencies over the previous 5 years. It confirmed that tooth-whitening procedures have minimal risk.⁴

In most states, tooth whitening services can be performed by dental professionals, nondental professionals, and virtually anyone who learns how to perform the procedure. Tooth whitening procedures are frequently offered at bridal shows, shopping malls, beauty salons, barbershops, and spas.⁵ Technical institutions are now offering courses to become certified tooth whitening specialists. There is concern regarding the quality of such courses and whether they cover important topics such as dental anatomy and oral pathology.⁵

Without adequate training, a nondental provider lacks basic knowledge of tooth anatomy, oral pathology, and infection control.⁴ This lack of expertise poses risks to consumers seeking whiter teeth and may come with legal implications for those providing tooth whitening services. As such, both dental and nondental service providers who perform tooth whitening procedures must fully understand the associated risks and the factors that may affect whitening outcomes.^6,7

State Regulations

For years, in-office tooth whitening was performed by dentists, registered dental assistants, and registered dental hygienists in the dental office.⁸ As the demand for whitening has grown, some states have expanded the ability to provide whitening procedures to nondental providers.

The North Carolina State Board of Dental Examiners accused several nondental service providers of practicing dentistry illegally by offering tooth whitening services.⁴ In 2015, the state’s Supreme Court ruled in favor of nondental providers, citing reduced costs for consumers.

On the other hand, Alabama prohibits nondental professionals from providing tooth whitening services and punishes those convicted with a 1-year jail sentence and a $5,000 fine.

In Connecticut, nondental providers who offer dental services, such as tooth whitening, pay up to $25,000 in fines and face 5 years in jail.

Benefits of Dental Professionals Performing Tooth Whitening Services

Oral health professionals perform an oral exam before whitening teeth.¹⁰ They are prepared to advise patients who may experience adverse effects from whitening such as pregnant or nursing women, those with cracked dentition, and individuals undergoing cancer treatment. They refer patients for additional treatment when they present with caries, restorative needs, periodontal diseases, and other dental issues. Oral health professionals help patients avoid common whitening mishaps, such as over-bleaching.^6,8

Dental professionals know the composition of restorative materials, including crowns, veneers, and composites, and are well aware that bleaching procedures do not whiten restorative materials. In fact, whitening agents may negatively impact the esthetic appearance of restorative materials.^1,9

Oral health professionals will apply a desensitizer gel before and after the bleaching procedure to avoid mouth irritation. In addition, the professional can recommend a recare schedule and advise the patient on maintaining the desired shade at home without over-bleaching.

Nondental Certified Tooth Whitening Specialist

The tooth whitening process may look different when a nondental provider is providing the service. Patients apply the bleaching solution independently while the tooth whitening technician guides them on placement. The nondental tooth whitening specialist cannot apply the bleaching gel.

Nondental tooth whitening specialists help in lip retraction, records and documentation, and checking if the patient applied the agent correctly. They provide the hydrogen peroxide and then monitor the patient under the laser lamp for 15 to 20 minutes.¹⁰ The compound should not exceed 16% hydrogen peroxide. Patients repeat the process for three to four sessions on the same day.

Etiology of Tooth Discoloration

With the growing popularity of tooth whitening, understanding why tooth discoloration occurs and how whitening works is important. Stains on the dentition are classified as intrinsic or extrinsic. Intrinsic stains penetrate the dentin. Extrinsic stains are found on the surface of the enamel.⁶ However, sometimes teeth appear yellow because the hard enamel has eroded, revealing the dentin underneath. This is usually caused by consuming coffee, tea, dark sodas, and highly pigmented fruits and vegetables.⁷ Tobacco chewing and smoking, poor oral hygiene, and certain medications can also contribute to extrinsic staining on teeth.⁷

The whitening process generally occurs when reactive oxygen molecules generated from hydrogen peroxide interact with organic chromophores through a chemical oxidation process that breaks up the double bonds of chromogens.⁸ Chromogens are the molecules that stain the teeth yellow. When the chromogens oxidize, they break up double bonds, allowing the molecules to become lighter.⁹ Unfortunately, with time, the double bonds of the chromogens will start to reappear, and the yellowish staining will return. Therefore, touching up is beneficial occasionally to maintain the desired shade.

Tooth whitening products use either carbamide peroxide or hydrogen peroxide and both are effective.⁹ Carbamide peroxide breaks down into hydrogen peroxide when it comes into contact with water or saliva. It contains hydrogen peroxide at a ratio of 1:3. This means that a product containing 30% carbamide peroxide has about 10% hydrogen peroxide.¹⁰ Most commonly used for at-home whitening treatments, carbamide peroxide releases half of its whitening power within the first 2 hours of treatment and can remain active for up to 6 additional hours. Because dental professionals do not supervise at-home whitening treatments, patients may over-bleach, which may harm the inside of the teeth.

Hydrogen peroxide breaks down much faster than carbamide peroxide, providing quicker results. The higher the concentration of hydrogen peroxide, the faster the compound will whiten teeth, but it will cause temporary dentinal hypersensitivity. Even though hydrogen peroxide works rapidly, it wears off quickly and becomes ineffective after 20 to 30 minutes.¹⁰ This is why most in-office whitening procedures require multiple sessions of 15 to 30 minutes and reapplication of bleaching agents.¹¹ Additionally, hydrogen peroxide must be kept refrigerated to expand its shelf life.

Hypersensitivity, although transient, is the most common side effect of tooth whitening. At-home treatments, over-the-counter whitening products, and in-office bleaching therapies can all cause sensitivity.⁹ Methods are available, however, to prevent, decrease, and/or eliminate dentinal hypersensitivity. Potassium nitrate and fluoride-containing whitening treatments have shown positive results in preventing and reducing dentinal hypersensitivity and demineralization.

Dental professionals should suggest brushing twice daily with potassium nitrate and fluoride toothpaste 2 weeks prior to initiating whitening treatment. When performing in-office whitening services, applying a prefilled disposable tray of potassium nitrate and fluoride after completion of therapy can help reduce post-bleaching discomfort.⁹

Tooth Whitening Modalities

Whitening techniques include dentifrice, prefabricated strips, trays, take-home whitening treatments, and, most recently, the do-it-yourself natural whitening remedies seen on social media.¹² Whitening toothpaste can remove surface stains, however, it cannot eliminate internal stains absorbed by the teeth. Most of these toothpastes remove tenacious surface stains due to their abrasiveness, which can wear down the enamel.^6,12–15

Charcoal toothpaste has become a widely touted whitening approach but it is highly abrasive and may cause gingival recession and thinning of the enamel. Teeth may appear yellow once the enamel is thinned.

Prefabricated whitening strips or one-size-fits-all whitening trays are popular and can be purchased online or at a local drugstore. They usually contain a low percentage of carbamide peroxide or hydrogen peroxide and require several applications over time, depending on manufacturer instructions.⁹ Hypersensitivity and gingival irritation are common side effects. Tissue trauma may also occur due to ill-fitting trays and overfilling of trays, which expose the oral mucosa to the whitening agent for an extended period.¹⁶

Over-whitening the tooth structure or improper tooth-whitening techniques may cause internal and external root resorption. The risks posed by ill-fitting, one-size-fits-all whitening trays are ameliorated by seeking tooth whitening in a dental setting. During the dental appointment, an impression/digital scan is taken so the bleaching trays are fabricated to fit each individual patient. The oral health professional recommends the type of bleaching agent and the percentage according to the patient’s current color shade and desired outcome. Once the desired shade is reached, the patient can use the trays to touch up the desired shade when necessary.

The in-office whitening procedure follows several steps to ensure the best results. It begins with taking a photo and evaluating the initial shade to assess the color of the teeth before adding a protective gingival barrier and retractor to protect the oral mucosa before using the hydrogen peroxide gel.^13,17 Oral health professionals use a combination of several gel layers and light to achieve the desired color with an interval of 15 to 20 minutes.¹⁸

Tooth Whitening Lights

Many in-office whitening procedures use a combination of hydrogen peroxide gel and light. Some over-the-counter products also incorporate a light-emitting diode (LED) with a whitening kit purchase. These light sources do not whiten teeth but work with whitening agents.¹⁹ These combinations expedite the whitening process by opening the molecules with the peroxide agent, allowing the whitening solution to penetrate the enamel more quickly. However, the use of light is optional for all products.

Two types of light are used during in-office teeth whitening treatments. The most common are ultraviolet (UV) or LED. UV lights are usually more potent than LED, as they use higher frequencies and emit heat.^10,20,21 The UV light uses magnetic radiation that transmits energy to produce this heat, which can pose risks to teeth, gingiva, lips, mouth, and eyes, if not used properly.

LED lights are blue and use less heat than UV lights, intensifying the whitening process without increasing the heat inside the teeth. They are energy efficient and effective without a significant risk of sensitivity and gingival irritation.^22,23

Conclusion

Individuals interested in tooth whitening should consult a dental professional to prevent bleaching-related sensitivity and other side effects.³ While over-the-counter and do-it-yourself products are on the market, oral health professionals are prepared to provide high-quality results in a safe environment.^20–24 Ultimately, the best tooth whitening method depends on the individual needs and preferences of the patient.  

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References

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From Dimensions in Dental Hygiene. November/December 2023; 21(10):36,39-41