Do-it-yourself tooth whiteners burst onto the scene a few years back and were quickly embraced by America’s culture of perpetual youth.
Cosmetic bleaching of teeth has been offered by dentists for a long time, but new technology brought the process right into the home, with a wide array of whitening products that included strips, gels, toothpastes, floss, dental rinses and even chewing gum.
There is no doubt that bleaching works. Teeth yellowed by age, caffeine, cigarettes and other ravages can be restored to pristine Chiclet beauty, and in-home tooth whitening is quick and simple.
But at what cost?
A tooth’s outer layer consists of translucent hydroxyapatite, a mineral made up of calcium phosphate. This enamel is the hardest tissue in the body.
Under the enamel is the dentin, a soft, off-white matrix of calcium phosphate and collagen that surrounds the blood vessels and nerves that give life to teeth.
When light passes through the tooth enamel, it is reflected back by the dentin, creating the normal “pearly white” appearance.
Dentists consider in-home tooth whitening to be both effective and safe when combined with regular dental exams and when people use a reputable bleaching product in accordance with its package directions.
The active bleaching ingredient in whitening products is peroxide: hydrogen peroxide and/or carbamide peroxide. Peroxides diffuse into the enamel and dentin in about 15 minutes.
The problems start when people overdo bleaching. Enamored by the appearance of their pearly whites in the mirror, many people use the products too often or at higher dosages than is recommended.
Teeth that are constantly and aggressively bleached may actually take on a bluish-white unnatural shade that dentists have begun calling “Regis white,” in honor of talk show host Regis Philbin’s Cheshire grin. Makers of dental materials – bridges, false teeth and composite fillings – have had to develop new, lighter shades in order to match teeth that have been artificially brightened.
Most tooth discoloration affects the surface enamel. Many substances – including red wine, coffee, tea, blueberries and other foods – can stain the enamel, as can cigarettes. Most of this staining can be removed by brushing. But over time, the discoloration can penetrate deeper into the enamel and become impossible to remove.
Certain antibiotics can cause tooth discoloration. Aging also causes teeth to fade, mostly due to deterioration of the dentin and a change in each tooth’s reflective ability.
The long-term effects of regular use of strong peroxides are unknown. Both hydrogen and carbamide peroxides produce free radicals, which may damage the cellular structure of gums and teeth.
Early research suggests that bleaching too aggressively or too often may cause permanent damage to gums and tooth enamel, as well as yielding a mouthful of sensitive, painful teeth.
One company, Proctor & Gamble, has conducted early research with Tufts University, with results suggesting that its Whitestrips are safe when used twice a day for six months. Until the long-term data is in, most dentists advise that their patients use the products sparingly.
“We’ll know in 10 years if [people] have done damage to their teeth,” said Bruce Matis, director of clinical research section at the Indiana School of Dentistry in Indianapolis.
Over-the-counter products are likely riskier than dental office whitening procedures. In the dentist’s office, the whiteners are applied with care – plastic barriers protect the gums and suction keeps the materials from draining down the throat.
In contrast, home procedures allow the bleach to contact not only the teeth, but also the gums, tongue, oral cavity and throat. Whitening material may also be swallowed.
Because of the unknown risks of exposure to high doses of peroxides, most dentists are recommending that pregnant women avoid tooth whiteners. Some also suggest that cancer patients and smokers avoid whitening products.
In Europe, over-the-counter whiteners must have a peroxide content no higher than one-tenth of 1 percent; anything stronger can only be administered in a dentist’s office.
Here in the United States, stronger products are easily available. For instance, Crest Whitestrips contain 6 percent hydrogen peroxide, while Rembrandt Plus and Colgate Simply White contain 10 percent and 18 percent carbamide peroxide, respectively.
Whitening toothpastes work by using abrasives to scrub and polish the tooth surface. Some of them also contain small amounts of peroxide, but it is not in contact with tooth enamel long enough to have much of an effect – whitening with peroxide takes time.
Whitening gums actually can have a lightening effect on teeth. However, one study noted that you would have to chew two pieces for at least 20 minutes four times a day to see even the slightest effect.
Tooth whitening comes with strong biological precedent. A robust smile and strong white teeth have long been associated with vigorous health, strength and even ferocity.
The market for tooth-whitening products is exploding. According to the Mintel International group, a market research firm, dentist-dispensed whitening products brought in $2 billion in 2005, compared to $435 million in 2000. As for over-the-counter whiteners, sales of $38 million in 2001 reached $351 million in 2005, a nearly 1,000 percent increase.
For those who cannot tolerate peroxide-based whiteners, another option bonds thin veneers of porcelain to the existing teeth. Porcelain veneers do not last forever, but they also do not stain and are maintenance-free.