Dental Whitening Revolution By Trisha E. O’Hehir, RDH, BS, Editorial Director, Hygienetown Magazine

Americans, especially the baby boomer generation, are obsessed with youth. The popularity of television’s Extreme Makeover is a testament to this infatuation. The show has featured tooth whitening – one, relatively inexpensive procedure to make people look younger – and that has fueled a consumer-driven “need” for tooth whitening.

It seems the number of whitening products increases daily. Consumer-whitening products began with gels in trays and now include whitening strips, paint-on products, and felt-tip applicators with whitening substances. In fact, in a recent e-mail survey* of dental hygienists conducted by Hygienetown, nearly all respondents (95%) recommend home-use whitening to patients and 70% said oral hygiene products were sold in their offices. The market is growing, the products are selling and the number of choices keeps increasing.

With all of the attention to tooth whitening today, it seems odd to think that it wasn’t too long ago dentists discouraged their patients from wanting white teeth, saying: “Teeth are shades from yellow to gray;” “Pure white teeth just aren’t natural;” and “Really white teeth are probably dentures.” With no solution being offered by the dental profession, consumers decided to take matters into their own hands, using Ajax or Comet cleanser to whiten their teeth.

There is no denying it, tooth whitening is big business. Over-the-counter whitening product sales were projected at $351 million last year in the United States, up from $38 million in 2001. Sales of whitening products dispensed from the dental office were $2 billion in 2005, up from $435 million in 2000, according to Mintel International.

When professional whitening products first entered the market, dentists were reluctant to offer the procedure because it was considered “cosmetic” rather than “therapeutic” – and therefore was “unprofessional.” The perception of tooth whitening changed with the public’s desire for whiter teeth.

In fact, my first experience with whitening was done to lighten an endodontically treated tooth that had darkened. The tooth was opened up from the lingual, a cotton pellet soaked with hydrogen peroxide was placed inside, and a photo flood light was used to speed the bleaching process. The high concentration of peroxide used destroyed the interdental papilla in the process, even with the use of a rubber dam. (It looked awful for weeks!) From those crude beginnings, bleaching has evolved into whitening and with it has come a revolution of change.

Although, 70% of respondents to Hygienetown’s e-mail survey* reported whitening was done by other staff members in the office, we know hygienists routinely field questions from patients about tooth whitening. Patients undergoing whitening procedures either in the office or at home want very white teeth, with no sensitivity, in the shortest time possible. Understanding the dynamics of whitening will help you answer your patients’ questions.

Whitening: How does it work?

Just as peroxide products lift color from hair, peroxide whitening products lift stain from tooth surfaces. Hydrogen peroxide is a combination of hydrogen and oxygen. There is an extra oxygen molecule that hunts for another molecule to attach to, in this case molecules of color within the enamel. The oxidation reaction breaks down the color trapped in the enamel surface into smaller particles that are released from the enamel.

Carbamide peroxide is a combination of hydrogen peroxide and urea. Adding urea to hydrogen peroxide stabilizes the formulation, produces a longer shelf life and improves taste. According to the research, both products whiten comparably, since the whitening is achieved by hydrogen peroxide in both cases.

Although the concentrations for hydrogen peroxide products appear to be lower than carbamide peroxide products, carbamide peroxide consists of one-third hydrogen peroxide and two-thirds urea. Therefore, a 10% carbamide peroxide product contains only 3% hydrogen peroxide and 7% urea. From the other side, a 9% hydrogen peroxide product is equivalent to 27% carbamide peroxide.

Whitening is achieved with a time/concentration approach. The shorter the time, the higher the concentration needed. The higher the concentration, the shorter the time needed. In-office products generally use peroxide at concentrations of 20–35% for short periods of time. At-home products are generally lower concentrations used over a longer time period.

Most in-office whitening is not sufficient to achieve the desired results in a single visit. According to a study reported in the February 2006 issue of Quintessence International, one to four visits are needed to achieve patient satisfaction with whitening results. Home-use products are provided to supplement and extend the in-office results and for touch-ups later. The primary advantage of in-office procedures is time. However, according to research published by Dr. Van Haywood of the Medical College of Georgia, whitening achieved with a lower concentration over a longer period of time is more stable than that achieved with a high concentration applied for a short time.

Can tetracycline stain be treated?

Even tetracycline staining can be altered with whitening over an extended period of time, or “deep bleaching.” Researchers have shown significant effects when the home-use whitening process is extended to six months or more. Other clinicians have found that preconditioning the teeth with several weeks of home-use whitening followed with a high concentration, in-office treatment effectively lightens tetracycline staining and/or fluorosis. According to Dr. Marshall White, the slow preconditioning of enamel with home-use whitening makes the enamel surface more receptive to greater color change later using a higher concentration, in-office procedure.

How white will the teeth be?

Teeth can be lightened from one to several shades. Patients should be prepared for some rebound as whitening procedures often dehydrate the enamel, leaving it lighter than it will be when again saturated with saliva. Explaining this to patients will prevent disappointment later.

How does the light work?

The heat from the light will speed the effect of the peroxide and also will dehydrate tooth surfaces. According to the research, the lights and lasers provide very little, if any, advantage over the whitening products used alone. More recently, whitening products have incorporated photo-activating substances to enhance the effect of the light or laser. The lights and lasers provide a psychological stimulus that patients find trendy and therefore desirable.

No pain no gain – does it always hurt?

Pain or sensitivity associated with whitening procedures is generally transient, lasts no more than 24 hours and can be alleviated with ibuprofen. Recommending the lowest concentration of peroxide will help in minimizing sensitivity. Still, the best approach is to prevent pain and sensitivity by recognizing problems prior to whitening. Ill fitting trays and overfilling trays with whitening gel can irritate and sting gingival tissues. Floss cuts and tissue abrasions are prime targets for peroxide irritation. A jolt or shock, often called a “zinger,” to a single tooth may be due to direct access of the peroxide to the dentin, due to cracked or chipped teeth or leaking margins on restorations. Determine the cause, and the problem can be addressed.

In addition, some manufacturers are adding sodium fluoride and potassium nitrate to whitening products to control sensitivity. Furthermore, some clinicians have their patients use a fluoride, sensitivity toothpaste or a remineralizing product for a couple of weeks prior to whitening. Others have patients use one of these products in the bleaching trays for 30 minutes before whitening or just after. Several new products and whitening formulations have been introduced recently to address the problem of sensitivity. Products containing amorphous calcium phosphate (ACP) not only reduce sensitivity, they also have been shown in laboratory studies to reduce susceptibility to enamel caries. Whitening doesn’t have to be painful when effective preventive measures are taken.

Conclusion

The whitening revolution is here to stay. Products are improving and more options are available now than ever before. Below is a reference table of companies that make in-office and home-use whitening to assist you in being ready with the answers when your patients ask about whitening.

Additionally, a good way to share knowledge and to learn what to say to patients is to join the discussions on www.hygienetown.com. While there, share the patient questions and concerns you’ve encountered regarding whitening, and the solutions you’ve offered them.